A woman with vasa praevia type II presents at 32 weeks with painless vaginal bleeding after rupture of membranes. Fetal heart rate shows sinusoidal pattern. What is the most important diagnostic test that should have been used antenatally to identify this condition?

• A Kleihauer-Betke test on maternal blood
• B MRI pelvis
• C Colour Doppler sonography of the lower segment ✓
• D Digital cervical examination

Explanation

Vasa praevia refers to fetal vessels running in the membranes across the internal os. Type II is associated with a velamentous cord insertion on a bilobed or succenturiate placenta. The gold standard for antenatal diagnosis is colour Doppler sonography of the lower uterine segment at the second-trimester anomaly scan. Kleihauer-Betke identifies fetal cells in maternal blood but cannot localise vasa praevia. Digital examination can rupture vessels and is contraindicated.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.