A 28-year-old at 38 weeks with a marginal placenta previa is admitted for elective delivery planning. On admission she has painless bright red vaginal bleeding. Which description of placenta previa localisation best identifies the lesion as 'marginal'?

• A Placenta covers the internal os completely
• B Placenta lower edge is within 2 cm of but does not reach the internal os
• C Placenta edge reaches but does not cover the internal os ✓
• D Placenta is in the lower segment but > 2 cm from the internal os

Explanation

The current RCOG/ACOG classification of placenta previa recognises two main categories: (1) placenta previa — where the placenta overlies the internal cervical os, and (2) low-lying placenta — where the placental edge is within 2 cm of the internal os. Historically, 'marginal' previa described a placenta whose edge reached but did not cover the os. This distinction matters clinically: true previa requires cesarean section, while low-lying placenta (edge 1–2 cm from os) may be managed with trial of vaginal delivery in selected cases with continuous monitoring.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.