A 27-year-old woman who delivered at home three months ago reports she never lactated and has not resumed menses. She had significant postpartum haemorrhage requiring transfusion. Serum prolactin is undetectable, TSH is low-normal with low free T4, and cortisol response to hypoglycaemia is blunted. The most likely mechanism of her pituitary failure is:
- A Lymphocytic infiltration destroying the pituitary stalk
- B Ischaemic necrosis of the enlarged anterior pituitary following peripartum hypotension ✓
- C Autoimmune apoptosis of gonadotrophs triggered by pregnancy oestrogens
- D Compressive infarction from a gestational prolactinoma
Correct answer: B. Ischaemic necrosis of the enlarged anterior pituitary following peripartum hypotension
Explanation
This is Sheehan syndrome: the pregnant anterior pituitary is hyperplastic yet supplied solely by the low-pressure portal system, so peripartum haemorrhage and hypotension cause ischaemic necrosis. Lactotroph failure appears first, giving absent lactation, followed by gonadotroph, thyrotroph, and corticotroph deficits. Lymphocytic hypophysitis can occur postpartum but typically presents with headache and mass effect rather than linkage to massive haemorrhage, and stalk destruction would raise rather than lower prolactin.
Reference: Williams Obstetrics, 26th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.