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)
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