From the Guidelines
For a 36-week pregnant patient presenting with contractions and bleeding, immediate evaluation is essential as this could indicate preterm labor, placental abruption, or placenta previa. The workup should begin with a thorough assessment of maternal and fetal status, including obtaining vital signs, performing a sterile speculum examination to visualize the cervix (avoiding digital examination if placenta previa is suspected), and initiating continuous fetal monitoring 1.
Key Steps in Workup
- Laboratory tests should include complete blood count, coagulation studies, and type and cross for potential transfusion.
- Ultrasound should be performed urgently to assess placental location, rule out placenta previa, and evaluate for abruption, as recommended by the American College of Radiology Appropriateness Criteria 1.
- Transabdominal US is the mainstay of obstetrical imaging, but transvaginal US may be particularly helpful in evaluating cervical-related causes of second and third trimester vaginal bleeding.
Management Approach
- If active labor is confirmed, administer betamethasone 12 mg IM, repeated in 24 hours, to accelerate fetal lung maturity.
- For tocolysis if indicated, consider nifedipine 10-20 mg orally every 4-6 hours or indomethacin 50 mg loading dose followed by 25 mg every 6 hours (limited to 48 hours due to fetal risks).
- Group B Streptococcus prophylaxis with penicillin G 5 million units IV initially, then 2.5 million units every 4 hours should be given if status is positive or unknown. The management approach should balance the risks of prematurity at 36 weeks (mild respiratory issues) against the potential dangers of continuing pregnancy with bleeding, which could indicate serious complications requiring prompt delivery 1.
From the Research
Workup for 36-Week Gestation Patient
Presentation
- The patient is experiencing contractions and vaginal bleeding at 36 weeks gestation.
- The workup for this patient should prioritize identifying the cause of the bleeding and assessing fetal well-being.
Possible Causes
- Placenta previa: a condition where the placenta covers the cervix, which can cause vaginal bleeding 2.
- Vasa previa: a rare disorder of placentation where fetal blood vessels are at risk of rupture, which can cause vaginal bleeding 3.
- Preterm labor: a condition where the patient goes into labor before 37 weeks gestation, which can cause contractions and vaginal bleeding 4.
Diagnostic Tests
- Ultrasound: to assess fetal well-being, placental location, and cervical length 3, 5, 4.
- Transvaginal ultrasound: to measure cervical length and assess for signs of preterm labor 4.
- Biomarkers: such as fetal fibronectin testing, to assess for signs of preterm labor 4.
Management
- Hospitalization: may be necessary to monitor the patient and fetus closely 3, 2.
- Corticosteroids: may be administered to promote fetal lung maturity 6, 2, 4.
- Tocolytics: may be administered to delay delivery and reduce the risk of preterm birth 4.
- Cesarean delivery: may be necessary if the patient has a placenta previa or vasa previa, or if the fetus is at risk 3, 2.