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Emergency and Acute Medicine: Vaginal Bleeding in Pregnancy
Vaginal bleeding in pregnancy is a major cause of maternal and fetal morbidity and mortality. It is categorized into early pregnancy bleeding (≤20 weeks), which occurs in up to 30% of pregnancies and results in spontaneous abortion in about half of cases, and late pregnancy bleeding (>20 weeks), which occurs in 3–5% of pregnancies. Risk factors include advanced maternal age, substance abuse, pelvic inflammatory disease, prior cesarean section, previous pregnancy loss or procedures, multiple gestations, hypertension, trauma, and assisted reproductive technology. A significant proportion of miscarriages (50–60%) are due to chromosomal abnormalities.
The etiology of bleeding may arise from vaginal, cervical, uterine, uteroplacental, or hematologic sources. In early pregnancy, important causes include implantation bleeding, spontaneous abortion (threatened, incomplete, complete, inevitable, missed), Ectopic pregnancy, gestational trophoblastic disease, subchorionic hemorrhage, and infection. In late pregnancy, the most critical diagnoses are Placenta previa and Placental abruption, along with vasa previa, uterine rupture, and labor-related bleeding.
Clinical presentation varies but key historical features include the amount and duration of bleeding, passage of clots or tissue, associated pain, and gestational age. Pain patterns can help differentiate causes: crampy diffuse pain suggests spontaneous abortion, sharp unilateral pelvic pain suggests ectopic pregnancy, painless bright red bleeding is typical of placenta previa, and painful dark bleeding is more consistent with placental abruption. Importantly, life-threatening conditions may present with minimal bleeding. Associated symptoms such as syncope, fever, or prior obstetric complications should also be assessed.
On examination, vital signs may show tachycardia or hypotension, although these can be masked by increased blood volume in pregnancy. Fetal heart activity is an important marker, detectable by transvaginal ultrasound at approximately 5–6 weeks and by Doppler after 10 weeks, with a normal rate of 120–160 beats per minute. Abdominal examination assesses uterine size and tenderness; a firm, tender uterus in late pregnancy suggests abruption. Pelvic examination is appropriate only in early pregnancy to evaluate the cervical os and source of bleeding. In late pregnancy, pelvic examination must be avoided until placenta previa or vasa previa is excluded by ultrasound due to risk of catastrophic hemorrhage.
The essential workup includes a complete blood count, blood type and Rh status, and quantitative β-hCG in early pregnancy. Ultrasound, particularly transvaginal ultrasound, is the most important diagnostic tool. It can confirm intrauterine pregnancy, identify ectopic pregnancy, detect retained products of conception, and visualize placental abnormalities. β-hCG levels help guide interpretation, though correlation is imperfect. Additional testing such as coagulation studies may be required in suspected disseminated intravascular coagulation, especially with placental abruption.
Management begins with stabilization. Patients with significant bleeding or instability require airway management, oxygen, cardiac monitoring, and two large-bore IV lines for fluid resuscitation and blood transfusion as needed. In late pregnancy, positioning the patient in the left lateral position helps reduce inferior vena cava compression and improve circulation. Continuous fetal monitoring is indicated in viable pregnancies.
Treatment depends on the underlying diagnosis. All early pregnancy bleeding must be evaluated for ectopic pregnancy. Unstable patients with suspected ectopic pregnancy require immediate surgical intervention, while stable patients may be candidates for methotrexate therapy. Threatened abortion is managed expectantly with close follow-up, while incomplete or septic abortion requires urgent obstetric consultation and possible uterine evacuation. Septic abortion also requires broad-spectrum antibiotics.
In late pregnancy, bleeding is an obstetric emergency requiring immediate consultation and hospital admission. Placental abruption may necessitate urgent delivery and management of coagulopathy, while placenta previa often requires careful monitoring and possible cesarean delivery. Any signs of disseminated intravascular coagulation must be treated aggressively with blood products.
Rh-negative patients must receive anti-D immunoglobulin to prevent alloimmunization. Failure to check Rh status and administer prophylaxis is a critical pitfall.
Disposition depends on stability and diagnosis. All patients with late pregnancy bleeding require admission. Early pregnancy patients may be discharged if stable with diagnoses such as threatened abortion or small, unruptured ectopic pregnancy after specialist consultation, but they require strict follow-up within 48 hours with repeat β-hCG testing and reassessment.
Key clinical pearls include always ruling out ectopic pregnancy in early bleeding, avoiding pelvic examination in late pregnancy until placenta previa is excluded, and recognizing that even minimal bleeding can represent a life-threatening condition.
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