What is the appropriate workup and management for vaginal bleeding during pregnancy?

Workup and Management of Vaginal Bleeding in Pregnancy

Immediate Assessment and Safety Considerations

Perform transvaginal ultrasound and obtain quantitative beta-hCG immediately—these are the two essential diagnostic tests that guide all subsequent management decisions. 1

Critical Safety Rule for Physical Examination

• Never perform digital pelvic or bimanual examination until ultrasound has excluded placenta previa, low-lying placenta, and vasa previa, as examination before imaging can precipitate catastrophic hemorrhage. 1, 2
• Speculum examination to assess for cervical lesions, polyps, or inflammation is appropriate after ultrasound excludes placental abnormalities. 1

First Trimester Bleeding (< 13 weeks)

Primary Diagnostic Workup

• Transvaginal ultrasound is superior to transabdominal ultrasound for early pregnancy evaluation and should be the primary imaging modality. 1
• Obtain quantitative beta-hCG level regardless of ultrasound findings. 1
• Order coagulation panel including fibrinogen in trauma cases. 2

Interpretation Algorithm Based on Ultrasound Findings

If intrauterine pregnancy is confirmed:

• Ectopic pregnancy is essentially ruled out (except rare heterotopic pregnancy). 1
• If subchorionic hemorrhage is present with viable pregnancy, schedule follow-up ultrasound in 1-2 weeks. 1
• Continue routine prenatal care with reassurance that 50% of first trimester bleeding results in viable pregnancy. 3

If pregnancy of unknown location (no intrauterine or ectopic pregnancy visualized):

• 80-93% will resolve as early intrauterine pregnancies or failed intrauterine pregnancies. 1
• 7-20% will later be diagnosed as ectopic pregnancies. 1
• Obtain serial beta-hCG measurements 48 hours apart. 1
• Repeat ultrasound when beta-hCG reaches the discriminatory threshold of 1,500-2,000 mIU/mL, at which point a normal intrauterine pregnancy must show a gestational sac on transvaginal ultrasound. 1
• Continue serial beta-hCG measurements until diagnosis is established. 1

Critical Diagnostic Limitations

• Ultrasound may miss up to 50% of placental abruptions and 74% of ectopic pregnancies initially, which is why serial beta-hCG monitoring is critical when the initial ultrasound is non-diagnostic. 1

Second and Third Trimester Bleeding (≥ 13 weeks)

Immediate Management Priorities

• For viable pregnancies (≥ 23 weeks), perform electronic fetal monitoring for at least 4 hours. 2
• Obtain obstetrical ultrasound to evaluate placental location and exclude placenta previa before any vaginal examination. 4, 2
• Assess maternal hemodynamic status and fetal well-being simultaneously. 2

Admission Criteria for Extended Monitoring (24 hours)

Admit patients with any of the following adverse factors: 2

• Uterine tenderness
• Significant abdominal pain
• Vaginal bleeding
• Sustained contractions (> 1 per 10 minutes)
• Rupture of membranes
• Atypical or abnormal fetal heart rate pattern
• High-risk mechanism of injury
• Serum fibrinogen < 200 mg/dL

Key Differential Diagnoses

Placenta previa:

• Classically presents as painless bleeding. 5
• Diagnosed on ultrasound; if found before 20 weeks, nearly 90% resolve by third trimester. 4
• Persistent previa in third trimester mandates pelvic rest and hospitalization if significant bleeding occurs. 4

Placental abruption:

• Most common cause of serious vaginal bleeding, occurring in 1% of pregnancies. 4
• May present with abdominal pain and bleeding. 5
• Management should not be delayed pending ultrasound confirmation, as ultrasound is not sensitive for diagnosis. 2
• May require rapid operative delivery to prevent neonatal morbidity and mortality. 4

Vasa previa:

• Rare but can result in fetal exsanguination with rupture of membranes. 4

Rh Status Management

• Administer anti-D immunoglobulin to all Rh-negative pregnant trauma patients. 2
• Perform Kleihauer-Betke test or equivalent to quantify maternal-fetal hemorrhage and determine need for additional doses of anti-D immunoglobulin. 2

Imaging and Radiation Considerations

• Radiographic studies including abdominal CT indicated for maternal evaluation should not be deferred or delayed due to concerns regarding fetal radiation exposure. 2
• Gadolinium-based contrast agents can be considered when maternal benefit outweighs potential fetal risks. 2

Follow-up Protocol

• For continuing pregnancies after initial evaluation, schedule follow-up ultrasound in 1-2 weeks. 1
• All pregnant trauma patients with viable pregnancy admitted for monitoring > 4 hours should have obstetrical ultrasound prior to hospital discharge. 2