A 30-year-old primigravida at 28 weeks with pre-eclampsia undergoes placental pathology after delivery. Which finding is MOST characteristic of the uteroplacental insufficiency underlying severe early-onset pre-eclampsia?
- A Villous edema and perivillous fibrin deposition
- B Excessive syncytial knot formation without vascular changes
- C Failure of physiological conversion of spiral arteries by extravillous trophoblasts ✓
- D Chorangiosis with >10 capillaries per villus
Correct answer: C. Failure of physiological conversion of spiral arteries by extravillous trophoblasts
Explanation
Early-onset pre-eclampsia is fundamentally a placentation disorder where extravillous cytotrophoblasts fail to invade and remodel the myometrial segment of spiral arteries, leaving them narrow, high-resistance vessels. This inadequate 'physiological conversion' results in placental ischaemia-reperfusion injury and the subsequent release of anti-angiogenic factors (sFlt-1, soluble endoglin) causing systemic endothelial dysfunction. Villous edema and perivillous fibrin are non-specific; chorangiosis reflects chronic hypoxia but is not the primary mechanism.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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