In placenta previa the placenta implants low in the uterus and covers the internal opening of the cervix. As the cervix changes late in pregnancy the placenta can bleed, and birth must be by cesarean delivery.
Key symptoms
- Painless bright red vaginal bleeding after 20 weeks
- Bleeding that may start after sex or with no trigger
- Often a first warning bleed that stops on its own
- Many cases found on a routine ultrasound with no symptoms
What you find on exam
- No digital cervical exam until previa is ruled out
- Soft, non-tender uterus
- Vital signs and estimate of blood loss
- Fetal heart rate monitoring, usually reassuring
Tests
- Transvaginal ultrasound to locate the placenta (safe and accurate)
- Blood count, type and screen or crossmatch
- Coagulation tests if bleeding is heavy
- Rh status and Kleihauer-Betke test in Rh-negative patients
Treatment basics
- Heavy bleeding: two large IV lines, fluids, blood products and emergency cesarean
- Stable bleeding: admit and monitor mother and fetus
- Betamethasone for fetal lung maturity if preterm
- Rh immune globulin if Rh negative
- Planned cesarean delivery at 36 to 37 weeks; no sex or vaginal exams until then
Red flags
- Heavy bleeding, falling blood pressure or fast heart rate
- Abnormal fetal heart rate tracing
- Prior cesarean with previa: suspect placenta accreta spectrum
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Sources: NCCPA PANCE Content Blueprint; NBOME COMLEX-USA clinical presentations; AAMC Core Entrustable Professional Activities (Core EPAs). Written by Making Synapses. Making Synapses is not affiliated with these organizations.