OB/GYN

PCOS & Amenorrhea Workup

OB/GYN

PCOS & Amenorrhea Workup

Primary vs secondary amenorrhea; PCOS management.

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◆Primary amenorrhea (no menses by 15)

•Breasts present (estrogen working):
• Uterus absent: Müllerian agenesis (46,XX) vs androgen insensitivity (46,XY)
• Uterus present: outflow obstruction (imperforate hymen, vaginal septum)
•Breasts absent:
• Low FSH: hypothalamic/pituitary (Kallmann)
• High FSH: gonadal failure (Turner 45,XO)

◆Secondary amenorrhea (cessation ≥3 months)

•First: pregnancy test (β-hCG)
•Then: TSH, prolactin
•If prolactin high: MRI pituitary (prolactinoma)
•If normal: FSH
• High FSH: premature ovarian failure
• Low FSH: hypothalamic amenorrhea (anorexia, athletes, stress)
• Normal FSH: PCOS, Asherman, outflow
•Progesterone challenge: withdrawal bleed = anovulation; no bleed = hypoestrogenic OR outflow

◆PCOS (Rotterdam criteria — 2 of 3)

•Oligo/anovulation
•Hyperandrogenism (clinical or biochemical)
•Polycystic ovaries on US
•Associated: insulin resistance, metabolic syndrome, T2DM, OSA, NAFLD
•Endometrial cancer risk from chronic anovulation

◆PCOS management

•Not pregnant: COCs (first-line — menstrual regulation + anti-androgen)
•Spironolactone for hirsutism/acne
•Metformin for insulin resistance
•Weight loss + lifestyle
•Pregnant: letrozole first-line (over clomiphene)
•Acanthosis nigricans suggests insulin resistance

High-yield pearls

◆Always pregnancy test first in secondary amenorrhea
◆Müllerian agenesis: 46,XX, normal T, no uterus, normal breast
◆Androgen insensitivity: 46,XY, high T, no uterus, no axillary/pubic hair, female phenotype
◆PCOS endometrial cancer risk → progestin to protect
◆Letrozole > clomiphene for PCOS infertility (less multiples, better live birth)

Quick check

5-question quiz on this note

Test yourself before moving on. ~1 min.

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