At a routine anomaly scan at 20 weeks, the placenta is anterior and its lower edge lies 18 mm from the internal cervical os. How should this finding be classified and managed?
- A Complete placenta previa requiring cesarean delivery
- B Low-lying placenta requiring repeat imaging around 32 to 36 weeks ✓
- C Marginal previa requiring admission from 28 weeks
- D Normal study requiring no follow-up
Correct answer: B. Low-lying placenta requiring repeat imaging around 32 to 36 weeks
Explanation
A placental edge within 20 mm of the internal os is termed a low-lying placenta under current RCOG and FIGO terminology. Most such cases migrate upward with lower segment development, so repeat transvaginal sonography at 32 and 36 weeks guides mode of delivery. Previa is reserved for a placenta covering the os, and no follow-up would miss persistent cases.
Reference: RCOG Green-top Guideline No. 27a, Placenta Praevia and Accreta, 2018 revision ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.