Initial basic approach to the differential diagnosis of obstetrical and gynecological causes of acute abdominal pain in pregnant women

* Ectopic pregnancies usually occur in the fallopian tube, but sometimes occur within the cervical canal or a cesarean delivery scar. Rarely, an ectopic pregnancy occurs concurrently with an intrauterine pregnancy. A pregnancy conceived via assisted reproductive technology (eg, in vitro fertilization) is a strong risk factor. Abdominal pain is a common symptom of all types of extrauterine pregnancy; vaginal bleeding, nausea, and vomiting sometimes occur but may be absent. Patients may present with tachycardia and hypotension due to intraabdominal bleeding. They may also have a low-grade temperature and a mild elevation in the white cell count. The diagnosis of ectopic pregnancy is usually based upon results from ultrasound examination and human chorionic gonadotropin hormone testing.
¶ Acute abruption classically presents with vaginal bleeding, abdominal and/or back pain, uterine tenderness, uterine rigidity, and uterine contractions; the fetal heart rate pattern may be abnormal. If significant placental separation develops, maternal disseminated intravascular coagulation and/or fetal death commonly occur. A retroplacental 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.
Δ Uterine rupture can be a catastrophic event. Signs and symptoms include nonreassuring fetal heart rate tracing or fetal death, uterine tenderness, peritoneal irritation, loss of fetal station, shock (due to intra-abdominal bleeding), and sometimes vaginal bleeding (which is generally modest). The possibility of rupture should always be excluded in women with a previous cesarean delivery and abdominal pain. Most uterine ruptures occur in laboring women with a prior cesarean delivery or prior transmyometrial uterine surgery (eg, myomectomy). Spontaneous rupture in the absence of labor may occur in women with a scarred uterus, but usually results from sharp or blunt abdominal trauma. Spontaneous rupture may also be related to a cornual pregnancy, pregnancy in a rudimentary uterine horn, or an interstitial pregnancy.
◊ 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.

• Preeclampsia is characterized by the new onset of hypertension and usually proteinuria after 20 weeks of gestation in a previously normotensive woman; 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 periportal or subcapsular bleeding or, rarely, hepatic rupture.
• Hemolysis with a microangiopathic blood smear, elevated liver chemistries, and a low platelet count are the findings in HELLP syndrome. The most common clinical presentation is abdominal pain and tenderness in the midepigastrium, in the right upper quadrant, or below the sternum. As with preeclampsia, the pain may be caused by stretching of Glisson's capsule due to 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.
• Acute fatty liver occurs in the second half of pregnancy, usually in the third trimester. The most frequent initial symptoms are nausea or vomiting, abdominal pain (particularly epigastric), anorexia, and jaundice. About one-half of patients have signs of preeclampsia at presentation or at some time during the course of illness. The diagnosis is usually made clinically based upon the setting, presentation, and compatible laboratory and imaging results. Laboratory tests may show elevated aminotransferases, elevated bilirubin, thrombocytopenia, prolonged prothrombin time, low glucose levels, increased uric acid levels, increased creatinine levels, and elevated white cell count. Imaging tests of the liver are primarily used to exclude other diagnoses, such as a hepatic infarct or hematoma.

§ Up to 20% of women with HELLP syndrome do not have hypertension.