Primary Amenorrhea

Risk factors

• Family history of delayed puberty or genetic disorders
• Chronic illness, malnutrition, low body weight
• Excessive exercise, eating disorders
• Stress, depression
• Pelvic radiation or chemotherapy

Pathophysiology

Menarche requires an intact hypothalamic-pituitary-ovarian axis, functional outflow tract, and adequate body composition. Disruption at any level — central (hypothalamus/pituitary), gonadal (ovary), or anatomic (uterus/vagina/hymen) — can prevent menses. Genetic causes (Turner syndrome, complete androgen insensitivity) are disproportionately common in primary amenorrhea.

Clinical presentation

Differential diagnosis

• Constitutional delay of puberty — Family history, short stature for age but normal growth velocity, delayed bone age; eventual spontaneous puberty
• Turner syndrome (45,X) — Short stature, webbed neck, shield chest, streak gonads; elevated FSH; karyotype (Noonan syndrome mimics the phenotype but has a normal karyotype, pulmonic stenosis, and usually spontaneous puberty)
• Müllerian agenesis (MRKH) — Normal breast development and pubic hair, absent uterus/upper vagina, normal 46,XX karyotype, normal ovaries
• Complete androgen insensitivity (46,XY) — Breast development, absent/scant pubic hair, blind vaginal pouch, testes (often inguinal); male-range testosterone; X-linked androgen receptor mutation: testicular AMH regresses Müllerian structures (no uterus) and aromatized testosterone produces breasts (vs 5-alpha-reductase deficiency: ambiguous genitalia, virilizes at puberty, no breasts)
• Imperforate hymen / transverse vaginal septum — Cyclic pelvic pain, hematocolpos; imperforate hymen = bluish bulging membrane at the introitus (hymenotomy); transverse septum = patent hymenal ring with a short blind vagina and obstruction higher in the canal on exam or MRI (surgical resection)
• Functional hypothalamic amenorrhea — Low BMI, excess exercise, stress; low FSH/LH, low estradiol
• Hyperprolactinemia — Galactorrhea; elevated prolactin; pituitary MRI
• Congenital adrenal hyperplasia — Ambiguous genitalia (classic), virilization; elevated 17-OHP
• Pregnancy — Always exclude with hCG even if patient denies sexual activity
• Swyer syndrome (46,XY complete gonadal dysgenesis) — Normal-to-tall stature, absent breast development (Tanner 1), uterus and cervix present because streak gonads make neither AMH nor testosterone, high FSH; gonadectomy at diagnosis for gonadoblastoma/dysgerminoma risk

Diagnostic workup

Diagnostic algorithm

flowchart TD
  A[Primary amenorrhea<br/>± delayed puberty] --> B[hCG, FSH, LH,<br/>estradiol, TSH, prolactin]
  B --> C[Pelvic ultrasound:<br/>uterus present?]
  C -->|No uterus| D[Karyotype + testosterone]
  D --> E[46,XX → Müllerian agenesis]
  D --> F[46,XY + high T<br/>→ Androgen insensitivity]
  C -->|Uterus present| G{FSH level}
  G -->|High| H[Hypergonadotropic<br/>→ karyotype<br/>Turner / Swyer / POI]
  G -->|Low/normal| I[Hypogonadotropic<br/>→ brain MRI<br/>Kallmann, prolactinoma,<br/>functional HA]
  G -->|Normal + outflow Sx| J[Outflow obstruction:<br/>imperforate hymen,<br/>transverse septum]

Treatment

Complications

• Osteoporosis from prolonged estrogen deficiency
• Cardiovascular risk in untreated hypogonadism (esp. Turner)
• Infertility and need for assisted reproduction
• Psychological impact of delayed development and fertility issues
• Gonadoblastoma risk in dysgenetic gonads with Y material — prophylactic gonadectomy indicated

PANCE pearls

• Always check a pregnancy test first, regardless of stated sexual history.
• Absent uterus + breast development → either Müllerian agenesis (46,XX, normal testosterone) or complete androgen insensitivity (46,XY, male-range testosterone).
• Cyclic pelvic pain in a patient with no menses suggests outflow obstruction (imperforate hymen, transverse septum).
• Y-chromosome material in a phenotypic female raises gonadal tumor risk: dysgenetic streak gonads (Swyer syndrome) are removed at diagnosis, whereas CAIS testes are usually removed after puberty (allowing spontaneous feminization), followed by estrogen replacement.
• Turner syndrome warrants cardiac (bicuspid aortic valve, coarctation) and renal imaging screening.

References

• ACOG CO 728 — ACOG Committee Opinion 728: Müllerian Agenesis: Diagnosis, Management, and Treatment
• ACOG CO 605 — ACOG Committee Opinion 605: Primary Ovarian Insufficiency in Adolescents and Young Women
• International Turner Syndrome Consensus Group 2024 — Gravholt CH et al. Clinical practice guidelines for the care of girls and women with Turner syndrome. Eur J Endocrinol 2024;190(6):G53-G151