A 16-year-old girl has never menstruated. Examination shows breast development (Tanner stage IV) and pubic hair present. She has a blind-ending vaginal pouch. Karyotype is 46,XY. What is the MOST likely diagnosis?

• A Complete androgen insensitivity syndrome (CAIS) ✓
• B Turner syndrome (45,X)
• C Müllerian agenesis (Mayer-Rokitansky-Küster-Hauser syndrome)
• D Congenital adrenal hyperplasia (21-hydroxylase deficiency)

Explanation

Complete androgen insensitivity syndrome (CAIS) presents with primary amenorrhoea, 46,XY karyotype, normal breast development (due to peripheral aromatisation of androgens to oestrogen), absent/sparse pubic and axillary hair, and a blind vaginal pouch. Testes are present intra-abdominally or inguinally. MRKH syndrome has 46,XX karyotype with absent uterus/vagina. Turner syndrome has 45,X with absent secondary sexual characteristics. The key triad for CAIS: 46,XY + phenotypically female + absent uterus.

Reference: Shaw's Textbook of Gynaecology, 17th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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