In vasa previa type II, what is the underlying anatomical basis that distinguishes it from type I?

• A Fetal vessels run through the cervix below the presenting part
• B Fetal vessels connect a succenturiate lobe to the main placenta and overlie the os ✓
• C Umbilical cord inserts velamentously into the lower uterine segment
• D Placenta praevia coexists with a marginal sinus rupture

Explanation

Vasa previa type I arises from a velamentous cord insertion where the unprotected fetal vessels traverse the internal os. Type II arises from fetal vessels connecting a bilobed or succenturiate lobe to the main placenta — these bridging vessels overlie the internal os without being associated with the cord insertion itself. Both types present with painless vaginal bleeding and fetal bradycardia (Apt test positive — fetal hemoglobin), but the anatomical origin differs.

Reference: Williams Obstetrics, 26th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.