In the pathophysiology of pre-eclampsia, failure of physiological transformation of spiral arteries is primarily due to inadequate trophoblastic invasion. At what gestational age does this pathological process begin?
- A 24-28 weeks
- B 16-20 weeks
- C 8-12 weeks ✓
- D 4-6 weeks
Correct answer: C. 8-12 weeks
Explanation
In pre-eclampsia, extravillous trophoblast fails to invade the myometrial segments of spiral arteries, typically beginning at 8-12 weeks gestation. This results in retention of muscular walls, high-resistance vessels, and reduced placental perfusion. The clinical syndrome manifests later (after 20 weeks) as a consequence of chronic placental ischemia releasing anti-angiogenic factors into maternal circulation. Option B (16-20 weeks) is when the second wave of trophoblastic invasion completes in normal pregnancy.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
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