🧬 Ambiguous Genitalia · Neonatal Decision Tool

Schwartz Clinical Handbook — Chapter 12 · CAH · Androgen insensitivity · Gonadal dysgenesis · SRY · 46,XX virilized · 46,XY undervirilized

Select physical exam findings, palpable gonads, electrolyte status, and family history to guide differential diagnosis of ambiguous genitalia in newborn.
⚠️ Medical emergency: salt-wasting congenital adrenal hyperplasia (CAH) can present with adrenal crisis (vomiting, hyponatremia, hyperkalemia) → immediate endocrine consult.

📋 Step 1 — Clinical & laboratory clues
📌 Diagnostic impressions
🧬 Schwartz Ch 12

Select external genital morphology, gonads, electrolytes, family history → system prioritizes 46,XX virilized (CAH most common) vs 46,XY undervirilized (androgen insensitivity, testosterone synthesis defects).

✔️ Bilateral palpable gonads → likely 46,XY (consider AIS).
✔️ Salt-wasting (hyponatremia, hyperkalemia) → 21-hydroxylase deficiency.
✔️ No palpable gonads + clitoromegaly → likely 46,XX CAH.
📘 Schwartz pearls (Chapter 12)
• Karyotype, pelvic ultrasound, 17-hydroxyprogesterone, and electrolytes are urgent.
• Gender assignment should be delayed until diagnosis (typically 48-72h).
• Family history of unexplained infant death → adrenal insufficiency / CAH.
• Refer to multidisciplinary team (endocrinology, urology, genetics, psychiatry).