A 35-year-old woman with two previous cesarean sections presents at 22 weeks with a posterior low-lying placenta, 15 mm from the internal os. What is the likelihood that this will resolve by 36 weeks?
- A Less than 10 percent
- B About 50 percent
- C Over 90 percent ✓
- D Zero percent, as it will become placenta previa
Correct answer: C. Over 90 percent
Explanation
Posterior low-lying placentas resolve in over 90 percent of cases by term due to differential growth of the lower uterine segment (trophoblast migration). Anterior placenta previa is less likely to resolve. A posterior placenta lying within 20 mm of the os at mid-trimester has an excellent chance of migrating away.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.