Reproductive · Year 2 · from Reproductive
Case 3: Placenta Previa
Clinical Image
Source: Wikipedia - Placenta praevia - CC BY-SA 3.0
Case Presentation
A 35-year-old G4P2 at 32 weeks gestation with a history of two prior cesarean deliveries presents to the emergency department with sudden onset of painless, bright red vaginal bleeding. She reports soaking two pads over 30 minutes. She denies contractions, abdominal pain, or trauma. Fetal movement has been normal. A routine 20-week anatomy ultrasound had noted a low-lying placenta, with follow-up recommended. Vital signs show heart rate 92 bpm and blood pressure 118/72 mmHg. Physical examination reveals a soft, non-tender uterus. Digital cervical examination is NOT performed. Continuous fetal monitoring shows a reassuring fetal heart rate pattern. Speculum examination shows blood in the vaginal vault with no cervical lesions. Transvaginal ultrasound confirms complete placenta previa, with the placenta entirely covering the internal cervical os. No retroplacental clot is seen. Laboratory studies show hemoglobin 10.2 g/dL. She is admitted for observation, pelvic rest, and betamethasone administration for fetal lung maturity. The bleeding stops spontaneously. She is counseled about the need for cesarean delivery (vaginal delivery is contraindicated with placenta previa) and the increased risk of placenta accreta given her prior cesarean deliveries. MRI is performed, which shows no evidence of placenta accreta. She remains hospitalized until delivery by planned cesarean at 36 weeks following repeat corticosteroids.
Key Learning Points
- Placenta previa presents with painless, bright red vaginal bleeding in the second or third trimester; digital cervical examination is absolutely contraindicated as it may precipitate hemorrhage
- Risk factors include prior cesarean delivery, prior uterine surgery, multiparity, and advanced maternal age
- Transvaginal ultrasound accurately diagnoses placenta previa and is safe when performed carefully
- Women with placenta previa and prior cesarean delivery are at increased risk for placenta accreta spectrum disorders; delivery must be by cesarean section