Evaluation and differential diagnosis of vaginal bleeding after 20 weeks of gestation

INTRODUCTION — Vaginal bleeding is less common in the second and third trimesters than in the first trimester. The clinician typically makes a provisional clinical diagnosis based upon the character of bleeding (eg, volume, associated with pain or painless, type of pain) and physical examination; imaging tests are used to support or revise the initial diagnosis.

The evaluation and differential diagnosis of vaginal bleeding in the second half of pregnancy (ie, 20 weeks or more of gestation) are discussed here. The evaluation and differential diagnosis of vaginal bleeding in the first half of pregnancy (ie, up to 20 weeks of gestation) are reviewed separately. (See "Evaluation and differential diagnosis of vaginal bleeding before 20 weeks of gestation".)

The management of pregnant patients with vaginal bleeding in the second half of pregnancy depends on numerous factors, including the gestational age, the cause of bleeding, the severity of bleeding, and fetal status. Management is discussed in the individual topic reviews on the specific causes of vaginal bleeding in this gestational age range.

INCIDENCE — Vaginal bleeding in the second half of pregnancy is estimated to occur in 2 to 7 percent of pregnancies prior to the onset of labor [1-4]. Reported incidence varies widely depending on the definition of bleeding and method of case ascertainment.

EVALUATION

Site — The site of patient evaluation depends upon the gestational age, severity of bleeding, and presence of other symptoms. Patients more than 20 to 22 weeks of gestation with more than spotting, lightheadedness/syncope, and/or pelvic pain warrant prompt evaluation on the labor and delivery unit where appropriate personnel and resources are available in the event of preterm birth of potentially viable newborn. Patients with spotting and no other symptoms may be evaluated in an office setting.

Goal — The goal of the evaluation is to make a definitive diagnosis when possible and exclude the presence of serious pathology in the remaining cases. The exact etiology of vaginal bleeding often cannot be determined, especially when bleeding is light [1-3].

History

Has an intrauterine pregnancy been documented? — Once an intrauterine pregnancy has been documented by ultrasound, an extrauterine pregnancy as the cause of bleeding is highly unlikely. Extrauterine intra-abdominal ectopic pregnancy or cornual ectopic pregnancy are rare exceptions as they may be erroneously reported as a normal intrauterine pregnancy if the sonographer does not carefully evaluate the relationship between the pregnancy and myometrium. (See "Abdominal pregnancy".)

What are the characteristics of the bleeding?

●Substantial bleeding with uterine contractions and abdominal pain – Substantial vaginal bleeding (eg, soaking a peripad, passage of clots) is usually related to placenta previa or placenta abruption. The presence of uterine tenderness, contractions, and abdominal pain often distinguish an abruption from a previa, but an ultrasound is usually required because a minority of abruptions are not associated with significant uterine pain/tenderness or contractions and a minority of previas are associated with these symptoms. Ultrasound will confirm the diagnosis of placenta previa if present; abruption is the likely diagnosis if previa is absent.

•(See 'Placental abruption' below.)

•(See 'Placenta previa' below.)

●Light bleeding with abdominal pain, hypotension, tachycardia – Light vaginal bleeding associated with constant abdominal pain accompanied by signs of intra-abdominal hemorrhage (eg, hypotension, tachycardia, increasing abdominal girth) are presumptive signs and symptoms of uterine rupture or extensive placental abruption. However, the degree, character, and location of pain are often variable, and the signs and symptoms of intra-abdominal or intrauterine bleeding can be subtle. Uterine rupture is most common in patients with a previous transmyometrial incision (eg, previous cesarean or myomectomy), and more common intrapartum than antepartum. (See 'Uterine rupture (in patients with previous hysterotomy)' below.)

●Light bleeding with no or minimal abdominal pain or contractions – Vaginal bleeding that is light, intermittent, and painless or associated with minimal abdominal pain and uterine irritability may be related to cervical insufficiency, a small placental abruption, placenta previa, a cervical or vaginal lesion (eg, polyp, infection, cancer), or impending labor ("bloody show").

•(See 'Cervical insufficiency' below.)

•(See 'Placental abruption' below.)

•(See 'Placenta previa' below.)

•(See 'Cervical or vaginal lesions' below.)

•(See 'Bloody show' below.)

Is there a recent history of trauma? — The possibility of abruption should always be considered in patients who are being evaluated for trauma (eg, motor vehicle crash, fall, domestic violence), especially if there was direct abdominal trauma. (See 'Placental abruption' below.)

Focused physical examination

Abdominal examination

●Uterine size, tenderness, tone – An abdominal examination is performed to assess uterine size, tenderness, and tone. The normal gravid uterus at 20 to 22 weeks is palpable at approximately the level of the umbilicus. After 20 to 22 weeks, the symphysis-to-fundal height measured in centimeters should correlate with the week of gestation. The normal uterus is soft similar to a relaxed skeletal muscle and nontender; bleeding associated with uterine firmness or rigidity and tenderness suggests abruption. (See 'Placental abruption' below.)

A smaller than expected uterine size associated with abdominal pain and/or contractions in a bleeding patient could be a sign of uterine rupture, with extrusion of the fetus, although this is rare. (See 'Uterine rupture (in patients with previous hysterotomy)' below.)

●Fetal cardiac activity – Absence of fetal cardiac activity on transabdominal ultrasound confirms fetal demise, which may be a consequence of the disorder responsible for the bleeding (eg, abruption, uterine rupture, vasa previa).

Inability to detect fetal cardiac activity by handheld Doppler ultrasound or a stethoscope is subject to clinician error and should always be confirmed by ultrasound examination. On the other hand, Doppler confirmation of fetal cardiac activity is reliable and reassuring, unless maternal tachycardia is present and misinterpreted as the fetal heart rate (simultaneously checking the maternal pulse can exclude this possibility). Doppler confirmation of fetal cardiac activity in a twin pregnancy may be misleading as a single fetal demise may be missed; ultrasound examination is required.

•(See 'Placental abruption' below.)

•(See 'Uterine rupture (in patients with previous hysterotomy)' below.)

•(See 'Vasa previa' below.)

Cervical examination — Digital examination of the cervix should be avoided in patients presenting with bleeding in the second half of pregnancy until placenta previa has been excluded by transvaginal ultrasound examination. Digital examination of a placenta previa can cause immediate, severe hemorrhage.

●In the second trimester (14 weeks and 0 days to 27 weeks and 6 days), cervical dilation and/or effacement is abnormal. If uterine contractions are absent, then cervical insufficiency should be suspected. (See 'Cervical insufficiency' below.)

●After 20 weeks of gestation, progressive cervical dilation and effacement over time that is associated with uterine contractions is diagnostic of labor, which can be associated with a small amount of bleeding, as well as mucus discharge and/or leaking of amniotic fluid. (See 'Bloody show' below and 'Labor' below.)

Ultrasonography — Ultrasonography is the cornerstone of the evaluation of bleeding in pregnancy and usually performed as soon as the focused history and physical examination have been completed. Transabdominal ultrasound is performed initially, followed by transvaginal ultrasound when the cervical area is the focus of the examination.

The primary goals are to determine whether the placenta is covering the cervical os (placenta previa), whether there is evidence of decidual hemorrhage causing placental separation (ie, placental abruption), and, in the second trimester, whether the cervix shows signs suggestive of cervical insufficiency (short length, dilated internal os, prolapsed fetal membranes). Sonography performs well for determining placental location and evaluating the cervix, but has low sensitivity for diagnosis of abruption. (See 'Placenta previa' below and 'Cervical insufficiency' below and 'Placental abruption' below.)

Role of speculum examination — A speculum examination should be performed in patients with bleeding and suspected leakage of amniotic fluid (eg, oligohydramnios on ultrasound, passage of watery blood) to determine whether membrane rupture has also occurred. It can be omitted in patients whom placenta previa or abruption is suspected based on history, physical examination, and/or ultrasonography. In patients in whom labor, placenta previa, or abruption is unlikely, speculum examination may confirm that the uterus is the source of bleeding or may reveal a vaginal or cervical source unrelated to pregnancy. (See 'Cervical or vaginal lesions' below.)

Laboratory tests

●A hemoglobin/hematocrit measurement should be performed as a baseline in patients with heavy vaginal bleeding and in those with suspected concealed retroplacental hemorrhage.

●Hemoglobin/hematocrit, coagulation studies, and type and screen or crossmatch should be obtained in all patients who are hemodynamically unstable (hypotension, tachycardia, orthostasis, syncope).

●RhD typing should be performed because anti-D immune globulin is administered to those with uterine bleeding to prevent alloimmunization from concurrent fetomaternal bleeding. (See "RhD alloimmunization: Prevention in pregnant and postpartum patients", section on 'Indications'.)

Measurement of human chorionic gonadotropin is unnecessary as part of the evaluation since the level will not be diagnostically informative.

DIFFERENTIAL DIAGNOSIS

Overview — The differential diagnosis of vaginal bleeding after 20 weeks can be difficult when bleeding is mild and relatively painless because several disorders share these characteristics, as shown in the table (table 1). In general:

●Ultrasound examination immediately makes the diagnosis of placenta previa or excludes it. (See 'Placenta previa' below.)

●Before 24 weeks, mild, painless, light bleeding requires cervical examination to evaluate for cervical insufficiency. (See 'Cervical insufficiency' below.)

●Bleeding accompanied by abdominal pain, uterine tenderness, and increased uterine tone is usually related to abruption. (See 'Placental abruption' below.)

●In patients with vaginal bleeding and/or abdominal pain and a prior cesarean birth or recent abdominal trauma, uterine rupture must always be considered and excluded. (See 'Uterine rupture (in patients with previous hysterotomy)' below.)

●Bleeding from vaginal and cervical lesions is readily diagnosed by visual inspection, with ancillary tests as indicated (eg, wet mount and pH of vaginal discharge, cervical cytology, and/or biopsy of mass lesions). (See 'Cervical or vaginal lesions' below.)

●In all of the aforementioned settings, the blood loss is maternal. Rarely, a patient will be found to have vasa previa on a routine second-trimester ultrasound examination. If these patients rupture membranes, fetal blood loss is a real possibility and life-threatening. (See 'Vasa previa' below.)

●Prelabor and early labor are often associated with light bleeding, which may contain mucous. These diagnoses should be clear based on the gestational age, cervical examination, and uterine contraction pattern. (See 'Bloody show' below and 'Labor' below.)

Most common antepartum etiologies — Placental abruption or placenta previa account for at least 50 percent of cases of antepartum bleeding. The etiology of the antepartum bleeding cannot be determined with certainty in most of the remaining cases. These cases are frequently attributed to marginal separation of the placenta.

Placental abruption — Placental abruption (abruptio placentae) refers to premature separation of a normally implanted placenta prior to birth. The degree of separation ranges from mild to severe (life-threatening to mother or fetus) and it may be acute or chronic. The most common risk factors include prior abruption, trauma, tobacco use, cocaine use, methamphetamine use, hypertension, and preterm prelabor rupture of membranes. The possibility of abruption should always be considered in patients who are being evaluated for abdominal trauma (eg, motor vehicle crash, fall, domestic violence). (See "Initial evaluation and management of major trauma in pregnancy", section on 'Placental abruption'.)

Abruption is a clinical diagnosis. Patients typically present with vaginal bleeding (80 percent), uterine tenderness (70 percent), and uterine contractions (35 percent), with or without abnormalities of the fetal heart rate pattern. Uterine tenderness is caused by extravasation of blood into the myometrium (called a Couvelaire uterus, an enlarged bluish-purple-appearing uterus due to the extravasation of blood through the myometrium to the serosa). In severe cases, blood can even penetrate to the peritoneal cavity. The amount of vaginal bleeding may not be a reliable indicator of the severity of the hemorrhage since bleeding may be concealed (retained in the uterine cavity).

The major purpose of ultrasound examination is to exclude placenta previa, not to diagnose or exclude abruption. Ultrasound examination is helpful when it identifies a retroplacental hematoma, which strongly supports the clinical diagnosis (positive predictive value 88 percent) [5-7], but many patients with abruption do not have this finding (sensitivity 25 to 60 percent [5,7-9]). (See "Acute placental abruption: Pathophysiology, clinical features, diagnosis, and consequences".)

Placenta previa — Placenta previa should be suspected in any patient who presents with vaginal bleeding in the second half of pregnancy. Classically, the absence of abdominal pain and uterine contractions was considered the clinical feature that distinguished between placenta previa and abruption, which is the other major cause of vaginal bleeding at this time. However, some patients with placenta previa have uterine contractions in addition to bleeding; thus, the diagnosis of placenta previa must be determined by sonographic examination.

The diagnosis of placenta previa is based on sonographic identification of echogenic homogeneous placental tissue extending over the internal cervical os on a second- or third-trimester imaging study (image 1), preferably using transvaginal ultrasound. Diagnosis and management are reviewed in depth separately. (See "Placenta previa: Epidemiology, clinical features, diagnosis, morbidity and mortality" and "Placenta previa: Management".)

Uterine rupture (in patients with previous hysterotomy) — Uterine rupture is an uncommon cause of vaginal bleeding; however, in patients with vaginal bleeding and a previous cesarean birth or transmyometrial surgery, the possibility of uterine rupture should always be considered. It usually occurs during labor or as a result of abdominal trauma but rarely occurs without an obvious precipitating cause. Abdominal pain, fetal heart rate abnormalities, and hemodynamic instability due to intra-abdominal bleeding are typical findings and indicate an obstetric emergency. The diagnosis is based on identification of a complete disruption of all uterine layers (including the serosa) at laparotomy. In cases without maternal or fetal compromise, the diagnosis may be made by ultrasound examination. (See "Uterine rupture: After previous cesarean birth" and "Uterine rupture: Unscarred uterus".)

Physical examination-based diagnoses — Bleeding associated with cervical and vaginal lesions is typically light and painless. Bleeding associated with cervical insufficiency is also typically light and painless, but mild uterine irritability or contractions may be present. Bleeding associated with labor is associated with uterine contractions, which are typically painful.

Cervical or vaginal lesions — These conditions are diagnosed by visual inspection, with ancillary tests as indicated (eg, wet mount and pH of vaginal discharge, cervical cytology, and/or biopsy of mass lesions).

●Vaginal laceration (see "Evaluation and management of female lower genital tract trauma")

●Vaginal neoplasm (see "Vaginal cancer")

●Vaginal warts (see "Condylomata acuminata (anogenital warts) in adults: Epidemiology, pathogenesis, clinical features, and diagnosis")

●Vaginitis (see "Vaginitis in adults: Initial evaluation")

●Cervical polyps, fibroids (see "Benign cervical lesions and congenital anomalies of the cervix")

●Cervicitis (see "Acute cervicitis")

●Cervical neoplasm (see "Invasive cervical cancer: Epidemiology, risk factors, clinical manifestations, and diagnosis")

Management of bleeding related to these conditions depends upon the specific condition. (Refer to individual topic reviews on each disorder).

Cervical insufficiency — The diagnosis of cervical insufficiency is clinical; the classic presentation is cervical dilation and effacement in the second trimester with fetal membranes visible at or beyond the external os in the absence of contractions or weak irregular contractions that appear inadequate to explain the cervical dilation and effacement. Symptoms include one or more of the following: vaginal fullness or pressure; vaginal spotting or bleeding; an increased volume of watery, mucus, or brown vaginal discharge; and mild discomfort in the lower abdomen or back.

On transvaginal ultrasound, cervical length is typically short (≤25 mm). Cervical dilation and prolapsed fetal membranes may also be present.

Management may involve placement of a cerclage and/or, more controversially, administration of vaginal progesterone. (See "Cervical insufficiency".)

Labor — The clinical findings that define true labor (ie, regular contractions resulting in cervical change) are the same whether labor occurs preterm or at term. The following prodromal signs and symptoms may be present for several hours before diagnostic criteria for labor are met:

●Spotting, light bleeding

●Menstrual-like cramping

●Mild, irregular contractions

●Low back ache

●Pressure sensation in the vagina or pelvis

●Vaginal discharge of mucus, which may be clear, pink, or slightly bloody (ie, mucus plug, bloody show)

(See "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment", section on 'Clinical findings' and "Preterm labor: Clinical findings, diagnostic evaluation, and initial treatment", section on 'Diagnosis'.)

Diagnoses of exclusion

Bloody show — "Bloody show" is the term used to describe the small amount of bloody mucus discharge that may precede the onset of labor by as much as 72 hours.

Rare etiologies

Vasa previa — Rupture of vasa previa is a rare cause of vaginal bleeding in the general obstetric population. The diagnosis vasa previa is based on sonographic visualization of membranous fetal vessels passing across or in close proximity (within 2 cm) of the internal cervical os by transvaginal ultrasound examination with color Doppler (image 2). The membranous vessels may be associated with a velamentous umbilical cord or they may connect the lobes of a bilobed placenta or the placenta and a succenturiate lobe. Risk factors for vasa previa include multiple gestation and in vitro fertilization.

In vasa previa, rupture of the membranous fetal vessels is an obstetric emergency because the blood is fetal in origin and likely to result in fetal death from exsanguination. In placental abruption, the bleeding is maternal in origin. A clinical diagnosis of ruptured vasa previa should be suspected in the setting of vaginal bleeding that occurs upon rupture of the membranes and accompanied by fetal heart rate abnormalities, particularly a sinusoidal pattern or bradycardia. Historically, tests such as the Apt or Kleihauer-Betke test or other tests (Ogita, Londersloot) were recommended for confirmation of fetal blood; however, typically there is no time to wait for test results before performing an emergency cesarean birth for fetal distress, thus these tests have a limited practical role in diagnosis or management. (See "Velamentous umbilical cord insertion and vasa previa".)

PROGNOSIS — The types and risks of adverse outcome appear to depend on the severity of bleeding and the cause [10]. Antepartum bleeding of unknown origin in the second half of pregnancy has been reported to increase the risk of preterm birth two- to threefold [1,11].

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: Obstetric hemorrhage".)

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 5^th to 6^th 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 10^th to 12^th 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 topics (see "Patient education: Bleeding in early pregnancy (The Basics)")

SUMMARY AND RECOMMENDATIONS

●General principles – Vaginal bleeding is less common after 20 weeks of gestation than before 20 weeks. The clinician typically makes a provisional clinical diagnosis based upon the character of bleeding (eg, volume, associated with pain or painless, type of pain) and physical examination; imaging tests are often used to support or revise the initial diagnosis. The goal is to make a definitive diagnosis when possible and exclude the presence of serious pathology in the remaining cases. (See 'Introduction' above and 'Incidence' above and 'Goal' above.)

●Etiology – Bleeding after 20 weeks of gestation is usually related to one of the following six entities. The signs and symptoms of these disorders can have substantial overlap, as shown in the table (table 1) (see 'Differential diagnosis' above):

•Placental abnormalities

-Placental abruption (see 'Placental abruption' above)

-Placenta previa (see 'Placenta previa' above)

•Uterine rupture (primarily in patients with a previous hysterotomy) (see 'Uterine rupture (in patients with previous hysterotomy)' above)

•Cervical or vaginal lesions (see 'Cervical or vaginal lesions' above)

•Cervical insufficiency (see 'Cervical insufficiency' above)

•Prelabor bloody show or labor (see 'Bloody show' above and 'Labor' above)

•Vasa previa (see 'Vasa previa' above)

●Diagnostic evaluation – Diagnostic evaluation includes obstetric and symptom history, focused physical examination, and usually ultrasonography. The differential diagnosis of vaginal bleeding after 20 weeks can be difficult when bleeding is mild and relatively painless because several disorders share these characteristics (table 1). Digital examination of the cervix should be avoided until placenta previa has been excluded by ultrasound examination as it can cause immediate, severe hemorrhage. (See 'Evaluation' above.)

•Ultrasound examination immediately makes the diagnosis of placenta previa or excludes it. (See 'Placenta previa' above.)

•Before 24 weeks, mild painless light bleeding requires cervical examination to evaluate for cervical insufficiency. (See 'Cervical insufficiency' above.)

•Bleeding accompanied by abdominal pain, uterine tenderness, and increased uterine tone is usually related to abruption. (See 'Placental abruption' above.)

•In patients with vaginal bleeding and/or abdominal pain and a prior cesarean birth or recent abdominal trauma, uterine rupture must always be considered and excluded. (See 'Uterine rupture (in patients with previous hysterotomy)' above.)

•Bleeding from vaginal and cervical lesions is readily diagnosed by visual inspection, with ancillary tests as indicated (eg, wet mount and pH of vaginal discharge, cervical cytology, and/or biopsy of mass lesions). (See 'Cervical or vaginal lesions' above.)

•In all of the aforementioned settings, the blood loss is maternal. Rarely, vasa previa is diagnosed on a routine second-trimester ultrasound examination. If membranes rupture in this setting, fetal blood loss is a real possibility and life-threatening. (See 'Vasa previa' above.)

•Prelabor and early labor are often associated with light bleeding, which may contain mucous. These diagnoses should be clear based on the gestational age, cervical examination, and uterine contraction pattern. (See 'Bloody show' above and 'Labor' above.)

●Management of RhD-negative patients – Patients with uterine bleeding who are RhD-negative are given anti-D immune globulin to protect against RhD alloimmunization. (See "RhD alloimmunization: Prevention in pregnant and postpartum patients".)