On obstetric ultrasound at 28 weeks, the placenta is noted to be low-lying with the placenta extending over the internal os. Colour Doppler shows multiple vascular lacunae within the placenta and loss of the hypoechoic retroplacental zone. These findings raise concern for:

• A Placental abruption
• B Circumvallate placenta
• C Placenta accreta spectrum (placenta accreta/increta/percreta) ✓
• D Velamentous cord insertion

Explanation

Placenta accreta spectrum (PAS) is characterised on ultrasound by multiple irregular intraplacental vascular lacunae ('moth-eaten' or 'Swiss cheese' appearance), loss of the normal hypoechoic retroplacental zone (normal retroplacental decidua), thinning or irregularity of the uterine serosa, and turbulent lacunar flow on Doppler. It occurs most commonly in women with prior uterine surgery (e.g., C-section). Placental abruption shows retroplacental clot. Velamentous insertion shows cord vessels crossing the membranes.

Reference: Grainger & Allison's Diagnostic Radiology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.