INTRODUCTION — The approach to acute abdominal/pelvic pain in pregnancy is similar to that in the nonpregnant state, with some additional challenges. The initial goal is to identify patients who have a serious or even life-threatening etiology for their symptoms and require urgent intervention. Additional issues during pregnancy include consideration of the effects of anatomic and physiologic changes related to pregnancy, causes of acute abdominal/pelvic pain that may be more common due to the pregnant state or related to obstetric complications, and the effect of the disorder on the fetus. Indicated diagnostic imaging and interventions should be performed since delay in diagnosis and treatment can increase maternal and fetal/newborn morbidity and mortality.
This topic will review issues specific to the diagnostic evaluation and management of acute abdominal/pelvic pain in pregnant and postpartum patients. The approach to acute abdominal/pelvic pain in other populations is discussed separately:
●(See "Evaluation of the adult with abdominal pain".)
●(See "Causes of abdominal pain in adults".)
●(See "Acute pelvic pain in nonpregnant adult females: Evaluation".)
GENERAL APPROACH — The goal in the evaluation of patients with abdominal/pelvic pain is to quickly identify those who have a serious or even life-threatening etiology for their symptoms and require urgent intervention. A history of any recent trauma is potentially relevant. Signs and symptoms that suggest a possible serious disease process include moderate or severe abdominal or pelvic pain, vaginal bleeding, new onset hypertension, hypotension, vomiting, or fever.
●Abdominal pain in a patient who has experienced trauma requires a trauma work-up (see "Initial evaluation and management of blunt abdominal trauma in adults" and "Initial management of trauma in adults"), with attention to pregnancy-related considerations. (See "Initial evaluation and management of major trauma in pregnancy".)
●Critical care ultrasonography (CCUS) is most commonly used in the emergency department and is an important diagnostic tool in pregnant patients. It may include bedside application of ultrasonography (eg, point-of-care ultrasonography [POCUS]). Protocols that describe the use of CCUS in critically ill patients who present with shock or trauma include rapid ultrasound in shock (RUSH), abdominal and cardiac evaluation with sonography in shock (ACES), focused assessment with sonography for trauma (FAST), and focused cardiac ultrasound (FOCUS). (See "Indications for bedside ultrasonography in the critically ill adult patient".)
●In the absence of recent trauma, we generally evaluate for pregnancy-related causes of pain first since these disorders are more likely to impact both the mother and fetus. A basic approach to differential diagnosis of serious pregnancy-related causes of abdominal pain is described in the algorithm (algorithm 1). (See 'Acute abdominal pain related to pregnancy or the reproductive tract' below.)
●Vaginal bleeding and hypertension are key signs of a potentially serious pregnancy-related cause of abdominal pain, but are not always present and not always indicative of a serious underlying disorder. (See 'Acute abdominal pain related to pregnancy or the reproductive tract' below.)
●Hypotension can be a sign of severe hemorrhage or septic shock. In the absence of trauma or vaginal bleeding, rupture of an intraabdominal blood vessel (eg, visceral artery aneurysm) or vascular organ (eg, splenic rupture) should be considered, although these disorders are rare. (See 'Medical-surgical causes of acute abdominal pain' below.)
Intraabdominal infection is common and may lead to sepsis, although septic shock is rare. The most common obstetric causes of sepsis are septic abortion, chorioamnionitis, endometritis, and wound infection [1]. Nonobstetric causes include pneumonia and infections of the urinary or gastrointestinal tract.
●Nausea and vomiting of pregnancy (NVP) is common in the first trimester and usually abates by 20 weeks of gestation (see "Nausea and vomiting of pregnancy: Clinical findings and evaluation"). Nausea and vomiting with onset in the second or third trimester or accompanied by pain, fever, hypertension, diarrhea, headache, fever, or localized abdominal/pelvic findings on physical examination is atypical and requires further evaluation. At a minimum, these patients should be evaluated for a primary gastrointestinal disorder or ovarian torsion, and those with epigastric pain and vomiting should be evaluated for pregnancy-related disorders such as the syndrome of hemolysis, elevated liver enzymes, and low platelets (HELLP). (See "Approach to the adult with nausea and vomiting".)
●Abdominal pain associated with fever has a broad differential diagnosis, and includes both infection and noninfectious etiologies. Intraamniotic infection (chorioamniotic) or degeneration or, rarely, torsion of a fibroid are potential pregnancy-related causes. (See 'Intra-amniotic infection' below and 'Fibroid degeneration or torsion' below.)
PHYSIOLOGIC CHANGES OF PREGNANCY THAT IMPACT DIFFERENTIAL DIAGNOSIS — Pregnancy complicates the diagnosis and differential diagnosis of abdominal/pelvic pain because physiologic changes associated with pregnancy can mimic clinical features of medical/surgical disorders associated with these symptoms, thus creating diagnostic uncertainty. For example:
●Early in pregnancy, the normal stretching of the round ligament may be associated with mild pelvic pain (see 'Round ligament pain' below). In the second half of pregnancy, especially in the third trimester, normal fetal position or movement, normal intermittent uterine contractions (Braxton-Hicks uterine contractions [ie, contractions not associated with labor/cervical changes]), or normal uterine enlargement can be associated with mild abdominal/pelvic discomfort.
In contrast, pain that is moderate or severe, associated with other symptoms (eg, nausea, vomiting, vaginal bleeding, headache, fever), or confined to one part of the abdomen suggests a pathologic entity. Peritoneal signs (rebound tenderness, abdominal guarding) are never normal in pregnancy [2], thus patients with these findings require additional evaluation.
●The uterus becomes an abdominal organ, enlarging beyond the pelvis by 12 weeks of gestation. This enlargement may make it difficult to localize pain as it can impede physical examination, affect the normal location of pelvic and abdominal organs, and mask or delay peritoneal signs (rebound, guarding) [2]. The normal laxity of the abdominal wall in pregnancy may also diminish peritoneal signs.
●The enlarged uterus may compress the urinary tract, leading to mild (usually) hydroureter and hydronephrosis [3] and thus mimic some signs of nephrolithiasis. (See "Maternal adaptations to pregnancy: Renal and urinary tract physiology" and "Acute kidney injury in pregnancy".)
●The enlarged uterus may cause aortocaval compression, resulting in lightheadedness or syncope when the patient is in a supine position [4]. This physiologic change resolves with a change in position (left lateral is best), but symptoms may be falsely attributed to internal bleeding from an acute disease process (eg, ruptured liver or spleen, ruptured visceral aneurysm). (See "Maternal adaptations to pregnancy: Cardiovascular and hemodynamic changes", section on 'Supine hypotensive syndrome'.)
●The high maternal progesterone level during pregnancy results in reductions in lower esophageal sphincter tone, small bowel and colonic motility, gallbladder emptying, and ureteral tone [5]. These physiologic changes are also important in the pathogenesis and diagnosis of conditions such as gastroesophageal reflux, constipation, cholelithiasis, and nephrolithiasis, all of which may be associated with abdominal pain. (See "Maternal adaptations to pregnancy: Gastrointestinal tract".)
●Physiologic changes in hematologic parameters may mimic values associated with infection and occult hemorrhage, making diagnosis of these disorders more difficult:
•White blood cell counts (WBC) increase to a normal range of 10,000 to 14,000 cells/mm3 during pregnancy [6]; in labor, the WBC count may be as high as 20,000 to 30,000 cells/mm3, returning to normal prepregnancy levels at approximately one week postpartum [7]. Bandemia is not a normal finding in pregnancy; therefore, its presence suggests infection until proven otherwise.
•A larger increase in plasma volume than in red blood cell volume results in physiologic anemia. The modest decrease in hemoglobin concentration (normal hemoglobin in pregnancy is ≥10.5 to 11.0 g/dL) coupled with the normal modest increase in heart rate (by 10 to 15 beats per minute in pregnancy) can be mistaken for signs of mild hemorrhage. (See "Maternal adaptations to pregnancy: Hematologic changes".)
●The range of normal for other laboratory values also may be altered in pregnancy (table 1). (See "Normal reference ranges for laboratory values in pregnancy".)
DIAGNOSTIC EVALUATION — An obstetrician should be part of the team when a pregnant patient with abdominal/pelvic pain is initially evaluated in the emergency department. Attention to detail, serial physical examinations, clinical awareness of nonobstetric and obstetric causes of abdominal pain, and systematic evaluation help avoid misdiagnosis and subsequent complications.
History and physical examination
●History – In addition to the usual diagnostic evaluation of adults with abdominal/pelvic pain (see "Evaluation of the adult with abdominal pain"), pregnant patients should be asked about their past and current obstetric history, as pregnancy complications may manifest as abdominal/pelvic pain (eg, preeclampsia may be associated with placental abruption or hepatic bleeding, previous cesarean birth is a risk factor for uterine rupture) and complications often recur in subsequent pregnancies.
The patient should also be asked whether they have any vaginal bleeding or leaking of fluid. Bleeding in the first half of pregnancy may be related to miscarriage or ectopic pregnancy. Placental abruption and labor are common causes of abdominal/pelvic pain in the second half of pregnancy and often accompanied by vaginal bleeding and rupture of the fetal membranes. Rupture of membranes alone, however, is painless. (See "Evaluation and differential diagnosis of vaginal bleeding before 20 weeks of gestation" and "Preterm prelabor rupture of membranes: Clinical manifestations and diagnosis".)
●Physical examination
•Vital signs – Obtain vital signs: Hemodynamic instability is an indication for immediate evaluation of pregnant patients. (See "Evaluation of the adult with abdominal pain".)
•Abdominal examination – Examine the abdomen: the examination is the same for pregnant and nonpregnant patients and includes inspection, auscultation, percussion, and palpation (see "Evaluation of the adult with abdominal pain"). However, the anatomical changes due to enlarged gravid uterus need to be considered.
•Uterus – Determine uterine size (which correlates with gestational age) and evaluate tone, tenderness, and, in the second half of pregnancy, frequency of contractions.
The normal uterus is nontender and soft, like any other relaxed muscle. A rigid or tender uterus in the second half of pregnancy suggests placental abruption, intrauterine infection, uterine rupture, or possibly labor. (See 'Second half of pregnancy' below.)
•Fetal heart rate – The fetal heart rate should be documented. Continuous fetal heart rate monitoring is usually appropriate in pregnancies that have reached a gestational age with a reasonable chance of extrauterine survival (≥22 weeks of gestation). An abnormal fetal heart rate may be the direct consequence of a pregnancy-related cause of abdominal/pelvic pain (eg, placental abruption) or it may be an indirect consequence of maternal compromise (eg, hypotension, infection). In either case, fetal resuscitation is usually indicated and urgent delivery may be appropriate. (See "Nonstress test and contraction stress test" and "Intrapartum category I, II, and III fetal heart rate tracings: Management".)
•Fetal membranes – Whether the membranes have ruptured or remain intact should be determined via a sterile speculum examination. (See "Preterm prelabor rupture of membranes: Clinical manifestations and diagnosis".) Rupture often leads to initiation of labor and may be associated with intrauterine infection or placental abruption. These entities are described in more detail below. (See 'Labor' below and 'Intra-amniotic infection' below and 'Placental abruption' below.)
•Cervix – Cervical dilation/effacement should be assessed by digital examination if the membranes are intact and ultrasound has confirmed the absence of placenta previa. Obstetric and nonobstetric disorders may lead to uterine contractions, which may result in cervical changes consistent with labor.
Laboratory — Laboratory tests can help narrow the differential diagnosis. As discussed above, the range of normal for multiple laboratory values also may be altered in pregnancy (table 1). (See "Normal reference ranges for laboratory values in pregnancy".)
In general, we suggest the following, unless a specific diagnosis is strongly suspected:
●Complete blood count with differential
●Urinalysis
●Basic metabolic panel (electrolytes and renal function)
●Liver and pancreatic biochemical and function tests (aminotransferases, bilirubin, amylase, lipase)
Pregnant patients with hemodynamic instability (hypotension or tachycardia) should have blood sent for coagulation studies and type and crossmatch. In the presence of fever or unstable vital signs possibly related to sepsis, blood and urine cultures are performed and may be helpful subsequently to confirm suspected infection and guide choice of antibiotic therapy. (See "Evaluation of the adult with abdominal pain".)
Imaging — Concerns about the possible fetal effects of ionizing radiation should not prevent performance of medically indicated diagnostic imaging procedures during pregnancy using the best available modality for the clinical situation [8]. A delay in diagnosis and treatment can increase the risk of an adverse maternal and/or fetal outcome [9,10]. (See "Initial management of trauma in adults", section on 'Diagnostic studies'.)
●Ultrasound – Ultrasound is the preferred modality for evaluating the fetus (gestational age, anatomic development, well-being [biophysical profile]), amniotic fluid volume, uterus, and other abdominopelvic viscera and for identifying collections of blood and other fluids. It is widely available, portable, nonionizing, and its diagnostic performance is often adequate. (See "Diagnostic imaging in pregnant and lactating patients" and "Overview of ultrasound examination in obstetrics and gynecology", section on 'Obstetric sonography'.)
●Modalities using ionizing radiation – The use of other modalities depends on the differential diagnosis and should consider availability, diagnostic performance, and fetal radiation exposure. When imaging using ionizing radiation is necessary, such as to evaluate bones for fracture or displacement and to detect foreign bodies and free air, radiologists should be familiar with various techniques beyond shielding the abdomen that can be employed to minimize the radiation dose [11].
Almost all diagnostic imaging procedures are associated with exposures that are well below the threshold for inducing congenital malformations, growth restriction, or neurodevelopmental delay. Whether there is a small increase in risk of carcinogenesis is controversial. Chest and abdominal radiographs are commonly used in evaluation of adults with abdominal pain. The estimated fetal absorption per chest radiograph is <0.01 mGy (<0.001 rad); this dose is well below doses that have been associated with any short- or long-term adverse effects [12]. The estimated fetal absorption for abdominal radiographs is 1 to 4.2 mGy (0.1 to 0.42 rad), which is also below doses that have been associated with short- or long-term adverse effects. The effects and appropriate use of diagnostic imaging (ionizing radiation, contrast materials, nuclear medicine scans, and MRI) in pregnancy are discussed in detail separately. (See "Diagnostic imaging in pregnant and lactating patients", section on 'Fetal risks'.)
●Magnetic resonance imaging – When indicated, use of magnetic resonance imaging (MRI) is preferable to computed tomography (CT) because it avoids ionizing radiation and, for diagnosis of many disorders, performs as well as or better than CT [13-15]. However, prompt diagnosis should not be delayed if MRI is not readily accessible. It is important to note that gadolinium crosses the placenta and may have potential harmful fetal effects. Therefore, the use of gadolinium generally should be avoided, but there may be some occasional clinical scenarios where the potential benefits are thought to outweigh the potential risks [16]. (See "Diagnostic imaging in pregnant and lactating patients", section on 'Magnetic resonance imaging'.)
Laparoscopy — Laparoscopy is sometimes indicated in the evaluation of acute abdominal/pelvic pain, especially when the diagnosis is not clear after less invasive evaluations and the differential diagnoses include potentially life-threatening or organ-threatening disorders. It is routinely performed in the first or second trimester, and usually remains technically possible into the third trimester. Based on retrospective evaluation and survey data, laparoscopic surgery for evaluation of abdominal/pelvic pain in pregnancy appears to be as safe as laparotomy. (See "Laparoscopic surgery in pregnancy".)
When surgery is planned, the appropriate services (Obstetrics, General Surgery, Anesthesia, Pediatrics) should be consulted. Management of pregnant patients undergoing surgery may require modifications to the technique used in nonpregnant females. (See "Anesthesia for nonobstetric surgery during pregnancy".)
ACUTE ABDOMINAL PAIN RELATED TO PREGNANCY OR THE REPRODUCTIVE TRACT
First half of pregnancy
Life-threatening causes
Ectopic pregnancy — All pregnant patients who present with lower abdominal pain with or without vaginal bleeding should undergo ultrasound examination to determine the location of the pregnancy, unless a normal intrauterine location has already been documented. (See "Ectopic pregnancy: Clinical manifestations and diagnosis".)
Ectopic pregnancies usually implant in the fallopian tube but implantation at other sites is possible (eg, cervical canal, ovary). Rarely, an ectopic pregnancy occurs concurrently with an intrauterine pregnancy. These heterotopic pregnancies can be difficult to diagnose; a pregnancy conceived via assisted reproductive technology (eg, in vitro fertilization [IVF]) is a strong risk factor. (See "Ectopic pregnancy: Epidemiology, risk factors, and anatomic sites", section on 'Heterotopic pregnancy'.)
Clinical manifestations vary somewhat depending upon the location and status of the pregnancy. Abdominal pain due to localized bleeding or rupture is a common symptom of all types of ectopic pregnancy. Vaginal bleeding is common with tubal or cervical pregnancies. Blood in the peritoneal cavity can be identified by ultrasound examination of the pelvis and abdomen. Patients with rupture may also have tachycardia, hypotension, low grade fever, and a mild elevation in the white cell count. (See "Ectopic pregnancy: Clinical manifestations and diagnosis", section on 'Clinical presentation'.)
The diagnosis of ectopic pregnancy is usually based upon results from a combination of ultrasound examination and serum human chorionic gonadotropin (hCG) hormone level in the early first trimester. Rarely, ectopic pregnancies progress to the second or third trimester; these pregnancies are typically attached to abdominal viscera (uterine serosa, adnexa, parametrium, liver, spleen, bowel, omentum).
Septic abortion — Septic abortion is a clinical diagnosis made in patients who present with signs and symptoms of uterine infection, including abdominal or pelvic pain, uterine tenderness, purulent vaginal discharge, vaginal bleeding, and/or fever following pregnancy loss or termination. The cornerstones of treatment are the rapid restoration of perfusion with intravenous (IV) fluid, initiation of IV antibiotics, and surgical evacuation of the uterus (algorithm 2). Antibiotics should be initiated immediately but do not replace surgical management for source control. (See "Septic abortion: Clinical presentation and management".)
Common causes
Round ligament pain — Early in pregnancy, unilateral mild sharp pelvic pain related to "stretching" of one of the round ligaments is a common benign process. Pain is more common on the right (as a result of dextrorotation of the uterus) and may be bilateral. The pain may radiate to the groin and labia majora. Vaginal bleeding is not present. There are no positive laboratory or imaging findings. Round ligament pain is a clinical diagnosis of exclusion. (See "Clinical manifestations and diagnosis of early pregnancy", section on 'Abdominopelvic pain'.)
Miscarriage — Miscarriage (or spontaneous abortion) is defined as the loss of a pregnancy before 20 weeks of gestation. Signs and symptoms include mild to moderate midline crampy pelvic pain and mild to moderate vaginal bleeding. (See "Pregnancy loss (miscarriage): Clinical presentations, diagnosis, and initial evaluation".)
Speculum and pelvic examinations are the first steps in the diagnostic evaluation. If no products of conception are identified grossly in the cervix or vagina, then ultrasonography is the most useful follow-up test. The sonographic signs of a nonviable pregnancy vary with gestational age. (See "Pregnancy loss (miscarriage): Ultrasound diagnosis".)
Uncommon causes
Uterine incarceration — Typically, patients with uterine incarceration present at 14 to 16 weeks of gestation with symptoms related to pressure on the anatomic structures adjacent to the entrapped enlarging uterus. The most common symptoms are pain and progressive difficulty voiding. The pain may be abdominal, suprapubic, or in the back, or may be limited to pelvic discomfort or a feeling of pelvic fullness. Urinary symptoms include frequency, dysuria, sensation of incomplete emptying, voiding small volumes due to overflow incontinence, and, often, urinary retention [17,18].
The diagnosis is based on ultrasound examination after the first trimester showing severe anterior displacement of the cervix and the uterus filling the posterior pelvis below the sacral promontory (figure 1). (See "Incarcerated gravid uterus".)
Second half of pregnancy
Life-threatening causes
Placental abruption — Acute placental abruption (ie, decidual hemorrhage leading to the premature separation of the placenta prior to delivery) classically presents with vaginal bleeding (except in concealed abruption), abdominal and/or back pain, uterine tenderness, uterine rigidity, and uterine contractions. The fetal heart rate pattern may be abnormal and is likely to be abnormal in pregnancies with substantial placental separation. In these cases, maternal disseminated intravascular coagulation and/or fetal death commonly occur.
A retroplacental, preplacental, or subchorionic clot is the classic ultrasound finding of placental abruption but is not always present. Diagnosis is based on clinical findings, and delivery is usually indicated. (See "Acute placental abruption: Pathophysiology, clinical features, diagnosis, and consequences" and "Acute placental abruption: Management and long-term prognosis".)
Pregnancy-related liver disease — Pregnancy-related liver diseases can cause epigastric or right upper quadrant abdominal pain. These disorders (preeclampsia with severe features, HELLP syndrome, and acute fatty liver of pregnancy) have overlapping features and can be difficult to distinguish (table 2).
Preeclampsia — Preeclampsia is a syndrome characterized by the new onset of hypertension and usually proteinuria after 20 weeks of gestation in a previously normotensive patient; right upper quadrant or epigastric pain is a sign of liver involvement and signifies the severe spectrum of the disease. The pain may be caused by stretching of Glisson's capsule due to periportal or subcapsular bleeding or, rarely, hepatic rupture. (See 'Hepatic rupture' below.)
The diagnosis is based on characteristic symptoms, findings on physical examination, and laboratory results (table 3A-B). (See "Preeclampsia: Clinical features and diagnosis" and "Preeclampsia: Antepartum management and timing of delivery".)
HELLP syndrome — Hemolysis with a microangiopathic blood smear, elevated liver transaminases, and a low platelet count are the findings in HELLP syndrome. The most common clinical presentation is abdominal pain and tenderness in the midepigastrium, right upper quadrant, or below the sternum. As with preeclampsia, the pain may be caused by stretching of Glisson's capsule due periportal or subcapsular bleeding or, rarely, hepatic rupture. It may not be possible to distinguish HELLP from preeclampsia with severe features, and they may be different manifestations of the same disease. (See 'Hepatic rupture' below.)
Many patients with HELLP also have nausea, vomiting, and malaise, which may be mistaken for a nonspecific viral illness or viral hepatitis, particularly if the serum aspartate aminotransferase and lactate dehydrogenase are markedly elevated (table 4). Hypertension (defined as blood pressure ≥140/90 mmHg) and proteinuria are present in approximately 85 percent of cases, but it is important to remember that either or both may be absent in HELLP. (See "HELLP syndrome (hemolysis, elevated liver enzymes, and low platelets)".)
Acute fatty liver of pregnancy — Acute fatty liver of pregnancy occurs after 20 weeks of gestation, usually in the third trimester. The most frequent initial symptoms are nausea or vomiting (approximately 50 percent of patients), abdominal pain (particularly epigastric, 50 percent), anorexia, and jaundice (30 percent). Approximately 70 percent of patients have signs of preeclampsia at presentation or at some time during the course of illness [19,20].
The diagnosis of acute fatty liver of pregnancy is usually made clinically based upon the setting, presentation, and compatible laboratory and imaging results. Laboratory test findings may show increased levels of aminotransferases, bilirubin, uric acid, ammonia, and creatinine; thrombocytopenia; prolonged prothrombin time; hypoglycemia; and leukocytosis. Imaging tests of the liver are primarily used to exclude other diagnoses, such as a hepatic infarct or hematoma, although some authors have reported finding fat on ultrasound, computed tomography (CT), or magnetic resonance imaging (MRI). Hepatic rupture is rare. (See "Acute fatty liver of pregnancy".)
Common causes
Labor — Labor should always be considered in the differential diagnosis of abdominal pain in pregnant patients, especially when symptoms are increasing over time It is a clinical diagnosis defined by uterine contractions of increasing frequency, intensity, and duration that cause cervical dilation and/or effacement over time. The presence of light vaginal bleeding and/or rupture of membranes increases diagnostic certainty in patients with minimal cervical dilation or effacement. By definition, labor is preterm at 20 to <37 weeks of gestation and term at ≥37 weeks of gestation. (See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment", section on 'Diagnosis'.)
Intra-amniotic infection — Signs and symptoms of intra-amniotic infection include fever, abdominal pain, uterine tenderness, leukocytosis, maternal and fetal tachycardia, and uterine contractions. It is most common in the setting of preterm or term rupture of the fetal membranes, with or without labor. (See "Clinical chorioamnionitis".)
Fetal position or movement — Mild abdominal/pelvic discomfort may be related to fetal position or movement. Low fetal station at term may result in pelvic discomfort, while in breech presentation, the fetal head may cause mild discomfort in an upper quadrant. Upper quadrant kicking at term may cause transient intermittent upper quadrant discomfort.
Discomfort from fetal position/movement can usually be diagnosed by history and abdominal and pelvic examination. Ultrasound can be used to confirm fetal position and correlate symptoms with observed fetal behavior.
Either first or second half of pregnancy
Common causes
Fibroid degeneration or torsion — The majority of fibroids remain asymptomatic in pregnancy [21-23]. Degeneration may occur and is more common with leiomyomas >5 cm in diameter. Most patients have only localized pain, although mild leukocytosis, fever, peritoneal signs, and nausea and vomiting can occur. Pedunculated fibroids are at risk of torsion; symptoms are similar to those with degeneration. Although degeneration can occur anytime in pregnancy, it is most likely to occur in the late first or early second trimester.
Fibroids are readily identified on ultrasound examination. Pain after ballottement by the abdominal ultrasound probe directly over the fibroid supports the diagnosis of degeneration or torsion. (See "Uterine fibroids (leiomyomas): Issues in pregnancy", section on 'Symptoms'.)
Bleeding ovarian cyst — Rupture of an ovarian cyst into the peritoneal cavity or intraovarian cyst bleeding may be associated with the sudden onset of unilateral lower abdominal pain. Although it can occur anytime in pregnancy, rupture is most likely to occur in the first or early second trimester. The pain often begins during strenuous physical activity, such as exercise or sexual intercourse. Rarely, bleeding is sufficiently severe to cause hemodynamic instability.
Ultrasound is the first-line imaging study for identification and characterization of the ovarian neoplasm and to look for fluid in the cul-de-sac. (See "Evaluation and management of ruptured ovarian cyst".)
Constipation — Constipation is common in pregnancy and may cause considerable abdominal discomfort. It is due to a combination of factors, including the effects of the hormonal changes of pregnancy on the gastrointestinal tract, mechanical effects of the enlarging uterus, reduced physical activity, intake of iron supplements or vitamins with iron, and changes in diet [24]. (See "Maternal adaptations to pregnancy: Gastrointestinal tract" and "Maternal adaptations to pregnancy: Gastrointestinal tract", section on 'Bloating and constipation'.)
Uncommon causes
Adnexal torsion — Adnexal torsion may involve the ovary, fallopian tube, or both structures. Ovarian torsion typically presents with right lateralized lower abdominal pain, frequently accompanied by nausea, vomiting, low-grade fever, and/or leukocytosis [25]. It occurs in all three trimesters but is most common in the first trimester and can occur postpartum. Risk factors include an ovarian cyst or mass and induction of ovulation, which can cause enlarged multicystic ovaries [25-27].
A presumptive diagnosis of torsion can be made with reasonable confidence in patients with acute pelvic pain and an adnexal mass with the characteristic sonographic appearance (including Doppler studies) of torsion and after exclusion of other conditions. A definitive diagnosis requires direct visualization of a rotated ovary at the time of surgery. The preferred treatment for a viable appearing ovary is to attempt to conserve the ovary by untwisting the pedicle to allow for the return of blood flow to and from the ovary. A salpingo-oophorectomy is required if the ovary is clearly nonviable (necrotic/gelatinous with loss of all normal anatomic structures) at surgery. (See "Ovarian and fallopian tube torsion".)
The presentation of isolated fallopian tube torsion is similar to ovarian torsion. Torsion is often associated with fallopian tube pathology (hydatid cysts of Morgagni, hydrosalpinx, and pyosalpinx). It commonly occurs on the right side, accompanied by nausea, vomiting, and lower abdominal pain. Ultrasound may help to identify a cystic structure in the pelvis, but differentiation between a paratubal and ovarian cyst is difficult. Diagnosis is made at the time of surgery in most cases and can be managed laparoscopically by experienced surgeons [28]. (See "Ovarian and fallopian tube torsion".)
Uterine torsion — Uterine torsion is rare and has been described in all trimesters (however, approximately 85 percent occur in the third trimester), as well as in nonpregnant females. It can be defined as rotation greater than 45 degrees around the longitudinal axis of the uterus [29]. Most patients have risk factors, such as fibroids, müllerian anomalies, fetal malpresentation, pelvic adhesions, and abdominal or ligamentous laxity.
According to literature reviews, rotation is 180 degrees in most cases, but can be up to 360 degrees, and the uterus is usually in dextrorotation [30-32]. Clinical manifestations vary depending on the degree of torsion: Abdominal pain, nausea and vomiting, obstructed labor, intestinal or urinary complaints, uterine hypertonus, vaginal bleeding, fetal bradycardia, and maternal shock have been reported.
Ultrasonography can lead to a correct diagnosis before delivery if a change in the previously determined placental site is noted (eg, from anterior to posterior) or the ovarian vessels are observed to pass in front of the lower uterine segment [31,33]. However, in almost all cases, the signs and symptoms of torsion lead to emergency cesarean birth, resulting in the correct diagnosis.
If derotation of the uterus with the fetus in situ is not possible, the fetus can be delivered through a transverse incision in the lower posterior uterine segment [29,34]. The uterus is then untwisted to its normal position. Prophylactic bilateral shortening of the round ligaments at delivery has been recommended to prevent recurrent torsion postpartum [35].
Several cases of fetal death (presumably due to ischemia), one maternal death, and one case of abruption have been reported [31,32,36]. Postpartum hemorrhage seems to be a frequent complication. A case of recurrence in two successive pregnancies has also been described [37].
Uterine rupture — Uterine rupture can be a catastrophic event. Signs and symptoms include nonreassuring fetal heart rate tracing or fetal death, uterine tenderness, abdominal pain, peritoneal irritation, vaginal bleeding, shock, and loss of fetal station.
Most ruptures occur in the third trimester. Most of the remainder occur in the second trimester; however, 61 cases of first trimester rupture have been reported (median gestational age 11 weeks) and most of these patients presented with severe abdominal pain and had previous uterine surgery [38].
Most uterine ruptures occur in laboring patients with a prior cesarean birth or prior transmyometrial uterine surgery (eg, extensive myomectomy). The possibility of rupture should always be excluded in such patients who have abdominal pain (see "Uterine rupture: After previous cesarean birth"). Rupture of an unscarred uterus in a laboring patient is rare; risk factors include grand multiparity, dystocia (malpresentation, macrosomia), obstetric procedures (breech extraction, uterine instrumentation, cephalic version), and prolonged or excessive use of uterotonic drugs. (See "Uterine rupture: Unscarred uterus".)
In nonlaboring patients, uterine rupture usually results from sharp or blunt abdominal trauma. It may also be related to a pregnancy in a rudimentary uterine horn or an interstitial pregnancy. (See "Initial evaluation and management of major trauma in pregnancy", section on 'Uterine rupture or penetrating injury'.)
Pelvic inflammatory disease — Pelvic inflammatory disease (PID) is rare during pregnancy because the cervical mucous plug and decidua form a barrier that protects the uterus from ascending bacteria. Other diagnoses should be considered before PID in pregnant patients with fever and lower abdominal pain. (See "Pelvic inflammatory disease: Clinical manifestations and diagnosis".)
MEDICAL-SURGICAL CAUSES OF ACUTE ABDOMINAL PAIN — An extensive list of causes of abdominal pain is provided in the tables (table 5A-B and figure 2). The location of the pain can be helpful in differential diagnosis, but is not pathognomonic, especially during pregnancy since uterine enlargement can distort normal anatomy. The most common potentially serious nonobstetric causes of acute abdomen pain in pregnancy are acute appendicitis, gallbladder-related disease, and small-bowel obstruction [39].
Upper abdominal pain
Life-threatening causes
Bowel obstruction — The risk of bowel obstruction during pregnancy increases as the uterus enlarges into the upper abdomen with advancing gestation. Adhesions and volvulus are the most common causes of the obstruction; intussusception is less common, and hernias are rare but should be suspected in those patients with a history of gastric bypass surgery who present with abdominal pain [40]. Patients with a history of gastric bypass who present with upper abdominal pain should be promptly evaluated by the surgical service. (See "Fertility and pregnancy after bariatric surgery", section on 'Bowel obstruction'.)
Colonic volvulus is more common during pregnancy than in the nonpregnant state [41]. (See "Cecal volvulus" and "Sigmoid volvulus".) Gastric volvulus is rare. (See "Gastric volvulus in adults".)
Clinical manifestations of bowel obstruction include crampy abdominal pain with vomiting and obstipation. Although nausea and vomiting are common and often a normal symptom of the first half of pregnancy, new onset later in pregnancy or coexistent abdominal pain or peritoneal signs are not normal and require evaluation. Other potential findings inconsistent with nausea and vomiting of pregnancy include abdominal distention, fever, and leukocytosis. Abdominal tenderness, rebound, and guarding can be variable during pregnancy.
Diagnosis and treatment are similar to that in nonpregnant individuals. Ultrasound may show dilated loops of bowel with air-fluid levels; flat and upright radiographs are more useful for looking for typical findings of obstruction and progressive bowel dilation over time (see 'Imaging' above). Magnetic resonance imaging (MRI) helps to characterize the site and degree of obstruction. Indications for immediate surgery are the same as for nonpregnant patients unless antepartum testing of fetal status is nonreassuring. (See "Etiologies, clinical manifestations, and diagnosis of mechanical small bowel obstruction in adults" and "Management of small bowel obstruction in adults".)
Perforated ulcer — Peptic ulcer disease is uncommon in pregnancy [42]. Symptoms include nausea, vomiting, and epigastric pain, which is often worse at night and postprandially. In contrast, gastroesophageal reflux disease is common in pregnancy and characterized by both regurgitation and pain, which is worse postprandially and with recumbency. (See 'Gastroesophageal reflux' below.)
Ulcer perforation should be suspected in patients with a history of peptic ulcer symptoms who develop the sudden onset of severe, diffuse abdominal pain. The characteristics of the pain and associated symptoms and physical findings (eg, tachycardia, low temperature, peritoneal signs) evolve over the first 12 hours after perforation. (See "Peptic ulcer disease: Clinical manifestations and diagnosis".)
Rapid diagnosis is essential since the prognosis is excellent within the first 6 hours but deteriorates with more than a 12-hour delay. Perforation is largely a clinical diagnosis with the history and physical examination providing essential clues. If imaging is required, plain abdominal radiographs are typically obtained first to detect diagnostic free air, although approximately 10 to 20 percent of patients with a perforated duodenal ulcer will not have free air. (See 'Imaging' above.)
Visceral artery aneurysm rupture — Rupture of a visceral artery aneurysm (typically splenic artery aneurysm) is rare. Splenic artery rupture has a strong association with pregnancy, usually in the third trimester, and is typically a catastrophic event with sudden hemodynamic collapse [43-45]. However, 20 to 25 percent of patients have an initial small, contained rupture that occurs hours before hemorrhage with circulatory collapse [43,46]. Presenting symptoms include sudden-onset diffuse abdominal pain centered in the epigastrium or left upper quadrant and radiating to the shoulder, anorexia, nausea, vomiting, syncope, and diarrhea or constipation. In stable patients, a curvilinear or signet-ring shaped calcification on an abdominal radiograph is strongly suggestive of splenic artery aneurysm [44]. Treatment is recommended for all symptomatic visceral artery aneurysms in pregnant patients. (See "Overview of visceral artery aneurysm and pseudoaneurysm" and "Treatment of visceral artery aneurysm and pseudoaneurysm".)
Dissection and rupture of renal, uterine, and ovarian arteries and the aorta have also been described, mostly in case reports, and appear to be related to the physiologic and hemodynamic changes of pregnancy [45,47-52]. Patients with Marfan syndrome, Ehlers Danlos syndrome, or Turner syndrome are particularly at risk. (See "Heritable thoracic aortic diseases: Pregnancy and postpartum care" and "Overview of the management of Ehlers-Danlos syndromes", section on 'Reproductive options and pregnancy' and "Clinical manifestations and diagnosis of Turner syndrome".)
Hepatic rupture — In pregnant patients, hepatic rupture is rare and most likely associated with HELLP syndrome, trauma, or preeclampsia with severe features (see 'Pregnancy-related liver disease' above). Other causes are extremely rare (eg, neoplasm, peliosis hepatis). (See "Peliosis hepatis".)
Symptoms include the sudden onset of severe pain in the epigastric and/or right upper quadrant radiating to the back, right shoulder pain, anemia, and hypotension.
If rupture is suspected, ultrasound examination may show intra- or extra-hepatic bleeding, but hepatic complications are best characterized by MRI or computed tomography (CT).
Common causes
Gastroesophageal reflux — Gastroesophageal reflux disease is more common during pregnancy. The most common symptoms are heartburn, regurgitation, and dysphagia; other symptoms include chest pain, water brash, globus sensation, odynophagia, and nausea. A presumptive diagnosis can be based on clinical symptoms. Indications for additional evaluation and treatment are reviewed separately. (See "Clinical manifestations and diagnosis of gastroesophageal reflux in adults" and "Medical management of gastroesophageal reflux disease in adults", section on 'Pregnancy and lactation'.)
Gallbladder disease — Pregnancy predisposes patients to formation of gallstones. The presentation of gallstone disease during pregnancy is not significantly different from the nonpregnant state. Affected patients typically complain of deep and gnawing pain that is occasionally sharp, colicky, and severe. The pain is localized in the right upper quadrant or epigastrium. There is often a history of fatty food ingestion one hour or more before onset of pain. As the gallbladder relaxes, the stones often fall back from the cystic duct. As a result, the attack reaches a crescendo over a number of hours and then resolves completely.
Acute cholecystitis refers to a syndrome of right upper quadrant pain that is steady and severe, fever, tachycardia, and leukocytosis associated with gallbladder inflammation, which is usually related to gallstone disease. Murphy's sign is variably positive (a positive Murphy's sign refers to pain resulting from palpating the area of the gallbladder fossa just beneath the liver edge while the patient is asked to inspire deeply. Patients may also have an associated inspiratory arrest).
Ultrasonography is the best method for making the diagnosis of cholelithiasis and differentiating this diagnosis from acute cholecystitis and chronic cholecystitis, when used along with history, physical examination, and laboratory findings. The white blood cell count and alkaline phosphatase level are normally elevated in pregnancy, which reduces the diagnostic usefulness of these laboratory tests (see 'Physiologic changes of pregnancy that impact differential diagnosis' above). Significant elevations of the transaminases and alkaline phosphatase or direct bilirubin should raise the possibility of a common bile duct stone, cholangitis, or the Mirizzi syndrome. (See "Gallstone diseases in pregnancy" and "Acute calculous cholecystitis: Clinical features and diagnosis" and "Mirizzi syndrome".)
Pneumonia — Pneumonia involving the lower lobes of the lung is a common cause of abdominal pain syndromes, presumably related to diaphragmatic irritation, and may be confused with acute cholecystitis or, rarely, an acute abdomen. Abdominal pain is occasionally the sole presenting symptom in a patient with lower lobe pneumonia. Common symptoms of pneumonia include cough, fever, pleuritic chest pain, dyspnea, and sputum production. (See "Clinical evaluation and diagnostic testing for community-acquired pneumonia in adults".)
An infiltrate on a chest radiograph is considered the gold standard for diagnosing pneumonia when clinical and microbiologic features are supportive. The estimated fetal absorption per chest radiograph is <0.01 mGy (<0.001 rad); this dose is well below doses that have been associated with any short- or long-term adverse effects [12]. (See "Approach to the pregnant patient with a respiratory infection", section on 'Community-acquired pneumonia' and 'Imaging' above.)
Uncommon causes
Acute hepatitis — Pregnancy generally does not affect the course of hepatitis A, B, or C, whereas patients with hepatitis E in the third trimester are predisposed to severe clinical disease. Cytomegalovirus, Epstein-Barr virus, and adenoviruses can also cause hepatitis in association with systemic infection. Constitutional symptoms of hepatitis include anorexia, nausea, jaundice, and right upper quadrant discomfort. The diagnosis is based on characteristic laboratory findings. (See "Overview of coincident acute hepatobiliary disease in pregnant women" and "Approach to evaluating pregnant patients with elevated liver biochemical and function tests".)
Pancreatic disease — Acute pancreatitis is a rare complication of pregnancy [53,54]; most cases are related to gallstone disease. Almost all patients have acute and persistent upper abdominal pain, which may radiate to the back, may be relieved with leaning forward, and may be accompanied by fever and postprandial nausea and vomiting.
The range of normal serum amylase and lipase levels are similar in healthy pregnant and nonpregnant patients; significantly elevated values should be considered pathologic (table 1) [55-58]. Ultrasound can be used to look for choledocholithiasis and pseudocyst formation. If further imaging is needed, MRI may be helpful. (See "Clinical manifestations and diagnosis of acute pancreatitis" and "Endoscopic retrograde cholangiopancreatography (ERCP) in pregnancy".)
Rupture of a solid pseudopapillary neoplasm of the pancreas, characterized by peritoneal signs, hypotension, and back pain, has been reported as an unusual cause of acute abdomen in pregnancy [59]. (See "Pancreatic cystic neoplasms: Clinical manifestations, diagnosis, and management".)
Rectus sheath hematoma — Rectus sheath hematoma is a rare cause of acute upper abdominal pain in pregnancy [60,61]. Risk factors for this disorder include female sex, coagulation disorders, anticoagulant use, trauma, abdominal straining (coughing, exercising, vomiting), degenerative muscular disease, prior abdominal surgery, obesity, and pregnancy, during which abdominal distention results in stretching and tearing of epigastric vessels.
Classic findings include a severe increase in abdominal pain with movement and an abdominal mass that remains unchanged with contraction of the rectus muscles. The hematoma, and resultant pain, is typically midline and often in the region below the ribs. Periumbilical and/or flank ecchymosis may be present, and hypotension can occur with severe bleeding.
Although ultrasound is typically the first-line imaging study (sensitivity 85 to 96 percent), CT is 100 percent sensitive in the diagnosis when the hematoma is less than five days duration. Laboratory evaluation may reveal anemia. (See "Spontaneous retroperitoneal hematoma and rectus sheath hematoma".)
Adrenal hemorrhage — Adrenal hemorrhage in pregnancy is a rare heterogeneous disorder that occurs in a wide variety of clinical setting It presents with nonspecific symptoms, most commonly abdominal pain; other signs and symptoms of adrenal insufficiency or lumbar pain may be present [62,63].
A high index of suspicion is needed for diagnosis, and MRI is the most sensitive and specific imaging modality. Conservative management with fluid resuscitation and correction of coagulopathies is necessary. Surgery is indicated for continued clinical deterioration despite aggressive resuscitative efforts, and adrenal insufficiency should be addressed in order to prevent circulatory collapse [64].
Adrenal vein thrombosis — Adrenal vein thrombosis in pregnancy is rare. Patients most commonly present with some symptoms similar to those with renal colic: unilateral lumbar pain (predominantly on the right side) and vomiting, but no fever. Abdominal and renal ultrasound are normal. A high index of suspicion is needed for diagnosis, which requires computed tomography (CT) with contrast. Therapeutic anticoagulation is the mainstay of treatment [65].
Hiatal hernia — The most common symptoms of hiatal hernia are epigastric or substernal pain, postprandial fullness, substernal fullness, nausea, and retching. The pain can be severe if the hernia incarcerates. The diagnosis is often made on the basis of characteristic clinical symptoms and findings on chest radiograph (see 'Imaging' above). Obesity is a risk factor. (See "Hiatus hernia".)
Wandering spleen syndrome — The wandering spleen syndrome is a rare cause of acute abdominal pain where the spleen migrates from its normal site to another location in the abdomen because of laxity or maldevelopment of the supporting ligaments. It is usually seen in younger adolescents and children, although it can occur in adults. Patients typically present with acute left upper quadrant pain associated with an abdominal mass. Ultrasound can help make the diagnosis [66]. (See "Causes of abdominal pain in adults", section on 'Less common causes'.)
Pain in the lower abdomen
Common causes
Acute appendicitis — Appendicitis is the most common cause of the acute surgical abdomen during pregnancy [67]. The most common symptom of appendicitis (ie, right lower quadrant pain) occurs maximally within a few centimeters of McBurney's point (1.5 to 2 inches from the anterior superior iliac spine (ASIS) on a straight line from the ASIS to the umbilicus) in the vast majority of pregnant patients, regardless of the stage of pregnancy.
The clinical diagnosis should be strongly suspected in pregnant patients with classic findings: abdominal pain that migrates to the right lower quadrant, right lower quadrant tenderness, nausea/vomiting, fever, and leukocytosis with left shift. However, pregnant patients are less likely to have a classic presentation than nonpregnant patients, especially in late pregnancy. The location of the appendix migrates a few centimeters cephalad with the enlarging uterus, so in the third trimester, pain may localize to the mid or even the upper right side of the abdomen, and tenderness at that point may be less prominent than in nonpregnant patients.
Graded compression ultrasonography is the first-line imaging modality. The primary goal of imaging is to reduce delays in surgical intervention due to diagnostic uncertainty. A secondary goal is to reduce, but not eliminate, the negative appendectomy rate. The clinical diagnosis of suspected appendicitis is supported by identification of a noncompressible blind-ended tubular structure in the right lower quadrant with a maximal diameter greater than 6 mm. The diagnosis should not be excluded if the appendix is not visualized, unless sonographic findings strongly suggest a likely alternative diagnosis (eg, ovarian torsion, nephrolithiasis). If ultrasound is inconclusive, MRI is the preferred next step imaging modality to avoid the ionizing radiation of CT scan. (See "Acute appendicitis in pregnancy".)
Uncommon causes
Nephrolithiasis — Symptomatic kidney stones during pregnancy affects less than 1 percent of pregnancies [68], but has been reported to be the most common non-obstetric indication for hospital admission in obstetric patients [69]. Most patients (at least 80 percent) present in the second or third trimester, typically with acute flank pain, which often radiates to the groin or lower abdomen. Stones occur with similar frequency on the left versus right side, and flank pain is on the same side as the stone. Hematuria is present in 75 to 95 percent of patients, one-third have gross hematuria and 40 percent have pyuria. Patients with a coexisting upper urinary tract infection often have fever.
When diagnostic ultrasound is performed, physiological hydronephrosis of pregnancy must be distinguished from pathological hydronephrosis from obstruction. Transvaginal ultrasonography should be performed in pregnant patients in whom transabdominal ultrasonography is not informative, and can help detect distal ureteral stones. Further options, when needed, include MRI urography or low-dose CT. In patients with clinical decompensation and diagnostic uncertainty after ultrasound examination, CT should be the next diagnostic imaging modality [69]. (See "Kidney stones in adults: Kidney stones during pregnancy".)
Inflammatory bowel disease — The pain of inflammatory bowel disease is crampy and associated with changes in bowel movements (frequent loose stools with blood and/or mucus). Pain ranges from mild to severe and positively correlates with other bowel symptoms. Fever and weight loss occur in severe disease. (See "Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults" and "Clinical manifestations, diagnosis, and prognosis of Crohn disease in adults".)
The course of inflammatory bowel disease during pregnancy appears to be determined, in part, by the activity of the disease at conception. The initial diagnosis is complicated in pregnancy and based on endoscopic findings or imaging studies in a patient with a compatible clinical history. (See "Fertility, pregnancy, and nursing in inflammatory bowel disease".)
Diverticulitis and Meckel's diverticulum — Most cases of diverticulitis occur after age 45. Although diverticulitis in pregnant patients has been described in case reports, several of these cases only involved Meckel's diverticulum [70-76]. Imaging modalities used in the diagnosis of appendicitis (ultrasonography, MRI, CT) may be helpful, but a high degree of clinical suspicion and surgical intervention is usually necessary to make the diagnosis [70,76,77]. (See "Clinical manifestations and diagnosis of acute colonic diverticulitis in adults" and "Meckel's diverticulum".)
Diffuse abdominal pain or pain in variable locations
Life-threatening causes
Trauma — Trauma is estimated to complicate approximately 1 in 12 pregnancies [78] and can lead to maternal and/or fetal death. The initial evaluation of the pregnant trauma patient should focus on establishing maternal cardiopulmonary stability. Any treatment required to save the mother's life or treat their critical status should be undertaken, regardless of the fetal status, including any diagnostic imaging deemed necessary. Obstetric providers (if available) should be notified of the patient as soon as possible upon presentation, or while the patient is en route, so that they can aid in the management and evaluation. (See "Initial evaluation and management of major trauma in pregnancy", section on 'Initial evaluation and management of major trauma'.)
Abdominal pain is a common consequence of blunt or penetrating abdominal trauma. The evaluation is similar to that in nonpregnant patients. (See "Initial evaluation and management of blunt abdominal trauma in adults" and "Initial evaluation and management of abdominal stab wounds in adults" and "Initial evaluation and management of abdominal gunshot wounds in adults".)
Once catastrophic trauma has been excluded, the obstetric clinician can determine whether the patient has any obstetric complications (eg, placental abruption, uterine rupture, fetomaternal hemorrhage, preterm labor, prelabor rupture of membranes). The majority of patients who develop adverse obstetric outcomes have symptoms such as contractions, vaginal bleeding, or abdominal pain upon initial presentation, but some may have minimal symptoms. (See "Initial evaluation and management of major trauma in pregnancy", section on 'Pregnancy evaluation and management after initial maternal stabilization'.)
Spontaneous hemoperitoneum — Spontaneous hemoperitoneum (spontaneous intraperitoneal hemorrhage) in pregnancy, defined as sudden nontraumatic intraperitoneal bleeding not caused by ectopic pregnancy or uterine rupture, is a rare life-threatening event [79-81]. Patients present with sudden onset of abdominal pain in the second half of pregnancy, often with hypovolemic shock and/or abnormal fetal heart rate. Exploratory laparotomy has revealed 500 to 4000 mL of blood in the abdomen, usually from bleeding superficial veins/varicosities on the posterior surface of the uterus or the left hemipelvis or from the uterine artery [82]. Thus, imaging by abdominal ultrasound typically shows free peritoneal fluid.
Risk factors include nulliparity, maternal age >35 years of age, multiple pregnancies, assisted reproductive technology, and history of endometriosis [82,83]. In one series, biopsy of the bleeding site was performed in five cases and endometriosis was identified in all [79]; in another series, 11 out of 11 patients had a history of endometriosis [80].
Timely intervention and control of bleeding allowed approximately half of reported pregnancies to deliver successfully or continue normally; the remainder ended in stillbirth or neonatal death. The surgical treatment is almost exclusively laparotomy. Bleeding can be controlled by suturing and/or the use of hemostatic agents; hysterectomy is rarely required [84].
In a prospective cohort study from Italy, laparotomy performed during pregnancy was accompanied by cesarean birth in approximately 85 percent of cases [83]. In rare hemodynamically stable patients, expectant management with close monitoring of vital signs might be possible, but complications include infected hematoma and recurrent bleeding [80].
Recurrence has been reported in the same and in future pregnancies [80].
Mesenteric venous thrombosis — Mesenteric venous thrombosis (MVT) can lead to bowel edema and, if arterial inflow becomes impaired, bowel infarction. The hallmark of acute MVT is abdominal pain that is typically described as colicky and midabdominal. Initially, the pain may be mild and initial physical findings may be normal. With progression of the disease, the pain can become severe and often out of proportion to the physical findings.
Pain can be accompanied by nausea, vomiting, and abdominal distention [85]. Fever, leukocytosis, and signs of peritoneal irritation, including rebound tenderness and rigidity, develop later and indicate transmural infarction, bowel gangrene, and peritonitis [86].
MVT has been described in pregnancy [87,88], where it may be related to the hypercoagulable state and compression of the mesenteric veins by the enlarged uterus. (See "Overview of intestinal ischemia in adults" and "Mesenteric venous thrombosis in adults".)
Common causes
Gastroenteritis, mesenteric lymphadenitis — Acute gastroenteritis is defined as diarrheal disease (three or more times per day or at least 200 g of stool per day) of rapid onset that lasts less than two weeks and may be accompanied by nausea, vomiting, fever, or abdominal pain. Severe abdominal pain is uncommon and identifies patients who may need hospitalization or evaluation for other causes. (See "Acute viral gastroenteritis in adults".) Severe abdominal pain suggestive of placental abruption has been reported in association with maternal enterovirus infection [89,90].
The signs and symptoms of mesenteric lymphadenitis mimic those of appendicitis (fever, periumbilical and/or right lower quadrant pain, and right lower quadrant tenderness, rebound) [91]. The disorder is most common in children and young adults.
Sickle cell crisis — In patients with sickle cell disease, anemia and vasoocclusive or acute painful episodes occur more often in pregnancy and are the most common maternal complications associated with pregnancy, occurring in over 50 percent of pregnant patients with the disease.
Vasoocclusive crisis may be difficult to distinguish from other causes of acute abdomen. Right upper quadrant symptoms are common in the setting of hepatic involvement or acute chest syndrome. Approximately 50 percent of episodes are accompanied by objective clinical signs such as fever, swelling, tenderness, tachypnea, hypertension, nausea, and vomiting. (See "Overview of the clinical manifestations of sickle cell disease" and "Sickle cell disease: Obstetric considerations" and "Hepatic manifestations of sickle cell disease".)
Uncommon causes
Clostridioides (formerly Clostridium) difficile — C. difficile-associated diarrhea with colitis is uncommon in pregnancy but may be increasing, particularly in postpartum patients [92,93]. Mild manifestations of the disease include watery diarrhea (≥3 loose stools in 24 hours) with lower abdominal pain and cramping, low grade fever, and leukocytosis. However, severe or fulminant colitis can also occur. The symptoms generally occur in the setting of recent antibiotic administration.
The diagnosis of C. difficile infection is established via a positive stool test for C. difficile toxin(s) or C. difficile toxin gene. (See "Clostridioides difficile infection in adults: Clinical manifestations and diagnosis".)
Hereditary angioedema — Hereditary angioedema is a rare genetic disorder that manifests with episodes of cutaneous or submucosal edema most commonly affecting the skin, the gastrointestinal tract, and the upper respiratory tract [94]. Two-thirds of females with hereditary angioedema experience exacerbation of symptoms during pregnancy, with the majority of exacerbations abdominal attacks [95,96]. Bowel edema manifests as varying degrees of gastrointestinal colic, nausea, vomiting, and/or diarrhea. Hives and pruritus are not present.
Ultrasonography is useful for evaluation of gastrointestinal attacks of these patients. The most common early finding is bowel wall edema, although this may resolve rapidly. Ascites may be the only finding during later stages of the attack. (See "Hereditary angioedema: Epidemiology, clinical manifestations, exacerbating factors, and prognosis" and "Hereditary angioedema (due to C1 inhibitor deficiency): Pathogenesis and diagnosis".)
Psoas abscess — An abscess of the psoas muscle is a rare cause of abdominal pain in pregnancy or postpartum and has only been described in case reports [97-99]. Patients usually present with vague findings including back pain, difficulty with ambulation, weight loss, and malaise. Diagnosis requires a high clinical suspicion in a patient with a history of intravenous drug misuse. Physical examination findings may include fever, costovertebral angle tenderness, lower back tenderness, or a mass in the groin. CT or MRI may help to diagnose the abscess and guide treatment. (See "Psoas abscess".)
Anterior cutaneous nerve entrapment — Anterior cutaneous nerve entrapment syndrome typically causes chronic abdominal wall pain. On physical examination, the patient is able to point with one finger to the area of maximal tenderness. The point of maximal pain is most often (55 percent) encountered on the right side of the abdominal wall, lateral or just caudal to the umbilicus. The patient may display the "hover sign," referring to using their hand to guard the affected area from the examiner's hands. Abdominal wall pain secondary to nerve entrapment is typically provoked by any activity in which the abdominal muscles are flexed. If the pain is exacerbated when the pain site is palpated while the patient flexes their abdominal wall, this is considered a positive test for neuropathic abdominal wall pain [100]. (See "Anterior cutaneous nerve entrapment syndrome".)
Abdominal wall hernia — Abdominal wall hernias may present with pain, bulging, or both. If severe, there may be signs of bowel obstruction. The hernias develop as a result of prior surgery (incisional) or spontaneously (umbilical, epigastric, Spigelian, or lumbar hernias). Presentation depends on the type and location of the hernia. (See "Overview of abdominal wall hernias in adults".)
Spontaneous rupture of the urinary tract — "Spontaneous" rupture of the urinary tract is diagnosed in the absence of recent trauma or surgery. Renal rupture can involve renal parenchyma or collecting system. It is extremely rare in pregnancy with only case reports in the literature [101].
Clinical presentation is similar to ureteric colic or pyelonephritis: sudden onset flank pain, most commonly right sided, with radiation to the lower abdomen or groin. Fever and chills may be present if there is an infection. In severe cases, the patient may present with an acute abdomen due to a retroperitoneal hematoma or urinoma if there is associated renal parenchymal involvement; a flank mass may be palpable on examination. Gross or microscopic hematuria may be detected in renal parenchymal rupture [102,103]. A high clinical suspicion and imaging (contrast enhanced computerized tomography scan or intravenous pyelogram) can aid in diagnosis. MRI can differentiate a hematoma from a urinoma. A delay in diagnosis can lead to abscess formation and possible nephrectomy.
Porphyria — Porphyria should be considered in the evaluation of any patient with unexplained abdominal pain (the most common symptom) or other neurovisceral symptoms (eg, insomnia, agitation, hallucinations, seizures) after an initial workup for common causes does not lead to a diagnosis [104-106]. (See "Porphyrias: An overview".)
CAUSES OF POSTPARTUM ACUTE ABDOMINAL PAIN — Any of the medical-surgical causes of abdominal pain discussed above can occur in the postpartum patient as well (table 6).
Life-threatening causes
Necrotizing soft tissue infection — Unexplained pain, which increases rapidly over time, may be the first manifestation of necrotizing soft tissue infection after cesarean birth or perineal laceration/episiotomy. Erythema may be present diffusely or locally, and thin, malodorous fluid may drain from the wound. However, in some patients, excruciating pain in the absence of any cutaneous findings is the only clue to the infection.
In addition to pain and skin findings, fever, malaise, myalgias, diarrhea, and anorexia may also be present during the first 24 hours. Loss of sensation may precede the appearance of skin necrosis and provide a clue that the process is necrotizing soft tissue infection rather than simple cellulitis.
It is important to consider this diagnosis in the setting of fever, soft tissue involvement with severe pain (out of proportion to skin findings in some cases), crepitus, rapid progression of clinical manifestations, and elevated serum creatine kinase level. Blood cultures should be obtained, but the diagnosis is established surgically. (See "Necrotizing soft tissue infections" and "Surgical management of necrotizing soft tissue infections".)
Abdominal compartment syndrome — Abdominal compartment syndrome generally occurs in patients who are critically ill due to any of a wide variety of medical and surgical conditions. In healthy patients, it should be considered when abdominal distension occurs in patients with unusually severe abdominal pain postcesarean birth. The syndrome is lethal if not diagnosed early. Findings noted on computed tomography (CT) imaging are bowel wall thickening, elevated diaphragm, and collapse of the inferior vena cava along with mucosal hyperenhancement and hemoperitoneum [107]. Definitive diagnosis of abdominal compartment syndrome requires measurement of the intra-abdominal pressure, which should be performed with a low threshold for diagnosis. (See "Abdominal compartment syndrome in adults".)
Group A streptococcal uterine infection — Group A streptococcal (GAS) infection is an uncommon but frequently life-threatening infection [108-111]. A broad spectrum of GAS postpartum infections can develop rapidly, ranging from mild endomyometritis (with absence of tachycardia and leukocytosis) to fulminant endomyonecrosis and death. The presentation varies slightly depending on the length of time since delivery. In one series of patients who developed the disease within two days of delivery, clinical findings included abdominal pain (58 percent), purulent vaginal discharge (38 percent), and uterine tenderness (31 percent) [110]. Gastrointestinal symptoms (diarrhea, nausea, vomiting) occurred in 31 percent of cases. Systemic symptoms included fever (73 percent), chills (35 percent), and hypotension (35 percent). Leukocytosis and tachycardia were not frequent findings.
Marked leukocytosis, hypotension, and tachycardia are signs of developing streptococcal toxic shock syndrome and are associated with higher mortality. However, leukopenia or a marked bandemia (greater than 10 percent) in the absence of a leukocytosis may be seen. Other signs and symptoms include an influenza-like syndrome (fever, chills, myalgia, nausea, vomiting, diarrhea), renal impairment, coagulopathy, hepatic dysfunction, adult respiratory distress syndrome, soft tissue necrosis, and generalized erythematous rash that may desquamate [112].
A pelvic examination should be performed; vaginal discharge and/or infection at the site of an episiotomy may be detected via direct observation (or with a speculum to visualize the entire vagina and cervix). (See "Pregnancy-related group A streptococcal infection".)
Common causes
Uterine involution (afterpains) — Midline, intermittent, lower abdominal and back pain are common normal symptoms postpartum and believed to be due to hypertonic uterine contractions. Typically, the pain is exacerbated by breastfeeding and is worse in multiparous than primiparous patients [113,114]. The pain usually resolves by the end of the first postpartum week. (See "Overview of the postpartum period: Normal physiology and routine maternal care", section on 'Afterpains'.)
Urinary retention — Vaginal birth (especially forceps-assisted), epidural anesthesia [115], and cesarean birth have been associated with postpartum urinary retention in non-catheterized patients. Patients may complain of suprapubic and abdominal pain and display varying degrees of bladder emptying. On examination, the fundal height may extend well above the umbilicus due to the excessively enlarged bladder. (See "Overview of the postpartum period: Disorders and complications", section on 'Voiding difficulty and urinary retention'.)
Endometritis — The diagnosis of postpartum endometritis is largely based upon clinical criteria of fever and uterine tenderness occurring in a postpartum patient. Other signs and symptoms that support the diagnosis include malodorous lochia, chills, and lower abdominal pain. The uterus may be soft and subinvoluted, which can lead to excessive uterine bleeding. Sepsis is an unusual presentation. Most cases develop after cesarean birth and within the first week after birth, but 15 percent present between one and six weeks postpartum. (See "Postpartum endometritis".)
Incisional complications — Complications related to an incision for cesarean birth (hematoma, seroma, infection, dehiscence) are a common cause of postoperative abdominal wall pain. The diagnosis is based on characteristic findings on physical examination, with ultrasound of the abdominal wall in cases of diagnostic uncertainty. Necrotizing soft tissue infection is uncommon, but life-threatening. (See "Cesarean birth: Postoperative care, complications, and long-term sequelae", section on 'Wound complications' and 'Necrotizing soft tissue infection' above.)
Uncommon causes
Ovarian vein thrombophlebitis and deep septic pelvic thrombophlebitis — Patients with ovarian vein thrombophlebitis (OVT) usually present within two to six days after delivery and within 10 days in 90 percent [116], but case reports describe diagnosis as late as five weeks postpartum [117]. Symptoms may include fever with lower abdominal pain radiating to the flank, upper abdomen, or groin on the side of the affected vein. The right ovarian vein is more commonly involved than the left (80 versus 6 percent), presumably because it is longer and has less competent valves than the left ovarian vein; bilateral involvement occurs in 14 percent of cases. Pelvic tenderness may reflect OVT or an alternative diagnosis such as endometritis. Nonspecific gastrointestinal symptoms such as nausea and ileus may occur, but are usually mild, which may be helpful in distinguishing right-sided OVT from appendicitis, pyelonephritis, or other processes. Although much less common, other pelvic vessels may develop thrombosis [118].
Patients with deep septic pelvic thrombophlebitis (SPT) usually present with fever in the early postpartum period (usually within three to five days), although the onset may be delayed to up to three weeks following delivery. They usually do not appear clinically ill; fever usually spikes and is associated with chills. Abdominal or pelvic tenderness is notably absent, which helps to distinguish SPT from OVT.
Imaging should be obtained to evaluate the pelvic vessels and for other potential processes. CT is the preferred diagnostic modality but MRI is acceptable; ultrasonography is not as useful. (See "Septic pelvic thrombophlebitis".)
Intra-abdominal or retroperitoneal hemorrhage — Intra-abdominal or retroperitoneal hemorrhage may be associated with abdominal pain, but more commonly manifests as hemodynamic instability (tachycardia, hypotension, or shock). Hemorrhage may be related to injury to a blood vessel at cesarean or vaginal birth or unrecognized uterine rupture during labor and delivery. (See "Overview of postpartum hemorrhage" and "Management of hematomas incurred as a result of obstetric delivery".)
Acute colonic pseudoobstruction (Ogilvie's syndrome) — Some degree of postoperative ileus is a normal physiologic response to abdominal surgery that generally resolves without serious sequelae. (See "Postoperative ileus".)
Acute colonic pseudoobstruction is a rare form of functional ileus in the distal bowel. It is more likely to occur after cesarean than vaginal birth [119] and more likely to occur in patients who received opioid analgesia in labor [120]. Physical examination is characterized by tense, tympanic abdomen, reduction or absence of peristalsis. The diagnosis is made only after excluding toxic megacolon or mechanical obstruction. (See "Acute colonic pseudo-obstruction (Ogilvie's syndrome)".)
In a systematic review of 65 cases of postpartum Ogilvie's syndrome reported between 2002 and 2016, the types and frequencies of symptoms were: abdominal distension (89 percent), abdominal pain (60 percent), vomiting (27 percent), fever (25 percent), constipation (16 percent), nausea (13 percent), and diarrhea (7 percent) [119]. Patients presented from six hours to eight days after delivery.
The diagnosis of Ogilvie's syndromes usually requires a colonic dilation of 9 cm or more; a dilation more than 12 cm is more frequently associated with perforation. In the same systematic review, six patients had cecal diameters >12 cm, and all of these patients perforated; 19 patients had cecal diameters of 9 to 12 cm, and 21 percent perforated; 17 patients had cecal diameters <9 cm, and 18 percent perforated.
Pregnancy-related liver disease — Hepatic manifestations of preeclampsia with severe features, HELLP syndrome, and acute fatty liver of pregnancy may develop or be first recognized postpartum. (See 'Pregnancy-related liver disease' above.)
Uterine inversion — Puerperal uterine inversion can follow vaginal or cesarean delivery. The clinical presentation depends on the extent and time of occurrence of the inversion. Symptoms include one or more of the following: mild to severe lower abdominal pain, mild to severe vaginal bleeding, urinary retention; hypotension out of proportion to blood loss may occur. The diagnosis is based on physical examination showing a smooth round mass protruding from the cervix or vagina. (See "Puerperal uterine inversion".)
Pubic symphysis separation — Separation of pubic symphysis >10 mm is considered pathologic. Clinical manifestations of pubic symphysis separation include localized pain to the suprapubic area, tenderness, swelling, and edema with pain radiating to the legs, hips, or back. The pain often increases with weight bearing, especially with walking and climbing stairs. Turning in bed, lifting, or getting up from a chair may also cause pain. Some patients report waking up during the night because of pain. Most patients describe these symptoms within 48 hours of childbirth, but there are cases in which symptoms began six months after giving birth [121].
The diagnosis is based on characteristic symptoms and physical examination: pain evoked by bilateral pressure on the trochanters or by hip flexion with the legs in extension. Rarely, a palpable groove at the level of the symphysis may be detected by internal or external examination. (See "Maternal adaptations to pregnancy: Musculoskeletal changes and pain", section on 'Pelvic girdle pain'.)
Foreign body — After cesarean birth, the possibility of a retained instrument or gauze sponge should be considered in patients with nonspecific abdominal pain, fever, nausea, and vomiting. However, patients may also present years after the surgery. The diagnosis is made radiographically; plain radiographs are the most common imaging technique. (See "Retained surgical sponge (gossypiboma) and other retained surgical items: Prevention and management".)
Unrecognized visceral injury — An unrecognized injury to the genitourinary or gastrointestinal system that occurred during a vaginal or cesarean birth or postpartum procedure for permanent contraception could lead to postpartum peritonitis, bowel obstruction, or bowel ischemia. (See "Complications of gynecologic surgery".)
Intra-abdominal or pelvic abscess — Pelvic abscess in females is usually a complication of pelvic inflammatory disease, but can also follow pelvic surgery or be related to an intra-abdominal inflammatory or septic process. (See "Epidemiology, clinical manifestations, and diagnosis of tubo-ovarian abscess".)
Myocardial infarction — Myocardial infarction (MI) is rare in females of childbearing age, although the risk is increased in the third trimester and the early postpartum period. Risk factors include the traditional coronary heart disease risk factors (diabetes mellitus, hypertension, smoking, thrombophilia) as well as maternal age over 35 years, postpartum hemorrhage, and postpartum infection.
Patients often complain of the development (over the course of minutes) of chest discomfort that is felt in the anterior chest or epigastric area and often with radiation to the shoulders, arms, jaws, or back. Shortness of breath and nausea may also be present.
The diagnosis of acute MI is generally guided by the same principles as in the nonobstetric population, including ischemic symptoms, electrocardiogram changes, and elevations in cardiac biomarkers. (See "Acute myocardial infarction and pregnancy".)
SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Nontraumatic abdominal pain in adults" and "Society guideline links: Postpartum care" and "Society guideline links: Ultrasound imaging in pregnancy" and "Society guideline links: Non-ultrasound imaging in pregnancy".)
INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5th to 6th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10th to 12th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.
Here are the patient education articles that are relevant to this topic. We encourage you to print or e-mail these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)
●Basics topic (see "Patient education: Abdominal pain (The Basics)")
SUMMARY AND RECOMMENDATIONS
●Relevant physiologic changes of pregnancy – When evaluating pregnant patients with abdominal pain, the clinician needs to consider the normal physiologic/anatomic alterations associated with pregnancy since they affect interpretation of signs and symptoms and laboratory results (table 1). (See 'Physiologic changes of pregnancy that impact differential diagnosis' above.)
Although abdominal discomfort, nausea, vomiting, and constipation can be a normal part of pregnancy, peritoneal signs (rebound tenderness, abdominal guarding) are never normal in pregnant patients. Nausea and vomiting are not normal manifestations of advanced pregnancy (after 20 weeks) and, when they occur with abdominal pain, fever, diarrhea, headache, or localized abdominal findings, require a thorough evaluation. (See 'Physiologic changes of pregnancy that impact differential diagnosis' above.)
●Diagnostic evaluation – Potential causes of abdominal pain can be considered based on the location of the pain (table 5A and table 5B).
•The goal of the diagnostic evaluation is to quickly identify those who have a serious or even life-threatening etiology for their symptoms and require urgent intervention. Signs and symptoms that suggest a possible serious disease process include (see 'General approach' above):
-Vaginal bleeding
-New onset hypertension
-Hypotension
-Moderate or severe pain
-Vomiting
-Fever
-History of recent trauma
•In addition to the usual diagnostic evaluation of adults with abdominal pain (see "Evaluation of the adult with abdominal pain"), key points in evaluation of pregnant patients include (see 'Diagnostic evaluation' above):
-Assessment of gestational age and fetal heart rate
-Past and current obstetric history
-Presence of vaginal bleeding or amniotic fluid leakage
-Uterine/cervical status
Prompt consultation with an obstetrician should be sought when a pregnant patient with abdominal pain is evaluated in the emergency department.
●Diagnostic imaging – Requisite diagnostic imaging and interventions should be performed as indicated since delay in diagnosis and treatment can increase maternal and fetal/newborn morbidity and mortality.
•Ultrasound – Abdominal and pelvic ultrasound examinations are the most useful tests for evaluation of abdominal pain in pregnant women. These examinations are safe for the fetus and perform well for making and excluding most diagnoses associated with abdominal pain.
•Ionizing radiation – When indicated, chest and abdominal plain films result in very low fetal absorption of ionizing radiation, and below doses that have been associated with short- or long-term adverse effects.
•Magnetic resonance imaging – Magnetic resonance imaging (MRI) does not involve ionizing radiation and thus is preferable to computed tomography (CT), which exposes the fetus to higher doses of ionizing radiation than plain films. (See 'Imaging' above.)
●Differential diagnosis – A basic initial approach to differential diagnosis of serious pregnancy-related causes of abdominal pain is provided in the algorithm (algorithm 1). Causes of abdominal pain that should be considered in postpartum patients are shown in the table (table 6). (See 'General approach' above.)
We generally assess for pregnancy-related causes of pain first since these disorders are more likely to impact both mother and fetus. Vaginal bleeding and hypertension are key signs of a potentially serious pregnancy-related cause of abdominal pain, but may be absent. (See 'Acute abdominal pain related to pregnancy or the reproductive tract' above.)
ACKNOWLEDGMENT — The editorial staff at UpToDate acknowledge Francisco J Orejuela, MD, who contributed to an earlier version of this topic review.
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