O&G · Reproductive endocrinology & infertility

Amenorrhoea & oligomenorrhoea: FIGO HyPO-P (2023) classification, WHO Group I/II/III workup, POI workup, outflow-tract MRI

Also known as Amenorrhea · Primary amenorrhoea · Secondary amenorrhoea · Oligomenorrhoea · Absent periods · FIGO HyPO-P · POI workup · Premature ovarian insufficiency investigation · Mullerian agenesis · Asherman syndrome

Exam-exhaustive FRANZCOG fellowship topic on amenorrhoea and oligomenorrhoea. Reproduces the 2023 FIGO HyPO-P classification verbatim (Hypothalamic Type I, Pituitary Type II, Ovarian Type III, PCOS Type IV; second-tier GAIN-FIT-PIE mechanism mnemonic) and the WHO 1973 three-group biochemical logic that drives treatment. Walks the structured investigation ladder — pregnancy exclusion, TSH, prolactin, day-2/3 FSH/LH/oestradiol, AMH, pelvic ultrasound, MRI pituitary with gadolinium for Group II pituitary, MRI pelvis for outflow-tract anomalies — and the POI workup (karyotype for Turner and FMR1, autoimmune screen with 21-hydroxylase antibodies, AMH). Covers Mullerian agenesis (MRKH), androgen insensitivity (CAIS), Asherman syndrome, cryptomenorrhoea, FHA, Kallmann syndrome, and Sheehan. Hyperprolactinaemia as a cause and the prolactinoma pathway live in the companion topic.

high14 referencesUpdated 28 July 202622 min readVerification in progress

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Red flags

Primary amenorrhoea with cyclical pelvic pain and a bulging blue-domed hymen — cryptomenorrhoea from imperforate hymen; urgent drainage (hymenectomy) to relieve obstruction and prevent retrograde endometriosis and tubal damage
Secondary amenorrhoea with FSH over 25 IU/L in a woman under 40 — premature ovarian insufficiency (a single elevated FSH suffices per ESHRE 2024); urgent karyotype, FMR1 premutation screen, autoimmune screen, fertility and HRT counselling
Secondary amenorrhoea with new severe headache, bitemporal hemianopia, or ophthalmoplegia — pituitary macroadenoma or pituitary apoplexy; urgent MRI and stress-dose hydrocortisone before imaging if apoplexy is suspected
Primary amenorrhoea with normal breast development but absent uterus on ultrasound — Mullerian agenesis (MRKH) or complete androgen insensitivity (CAIS); karyotype before any decision about gonadectomy or vaginal creation
Female athlete with amenorrhoea and a stress fracture — functional hypothalamic amenorrhoea from low energy availability; bone density assessment and multidisciplinary management, not the combined oral contraceptive pill alone
New mother with failure to establish lactation and persistent amenorrhoea after a major postpartum haemorrhage — Sheehan syndrome; full anterior pituitary workup including morning cortisol

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Saved on this device.

Practise this topic8 MCQs with explanations

Target exams

FRANZCOGMRCOGABOGFRCSCMRCPI

Red flags

Primary amenorrhoea with cyclical pelvic pain and a bulging blue-domed hymen — cryptomenorrhoea from imperforate hymen; urgent drainage (hymenectomy) to relieve obstruction and prevent retrograde endometriosis and tubal damage
Secondary amenorrhoea with FSH over 25 IU/L in a woman under 40 — premature ovarian insufficiency (a single elevated FSH suffices per ESHRE 2024); urgent karyotype, FMR1 premutation screen, autoimmune screen, fertility and HRT counselling
Secondary amenorrhoea with new severe headache, bitemporal hemianopia, or ophthalmoplegia — pituitary macroadenoma or pituitary apoplexy; urgent MRI and stress-dose hydrocortisone before imaging if apoplexy is suspected
Primary amenorrhoea with normal breast development but absent uterus on ultrasound — Mullerian agenesis (MRKH) or complete androgen insensitivity (CAIS); karyotype before any decision about gonadectomy or vaginal creation
Female athlete with amenorrhoea and a stress fracture — functional hypothalamic amenorrhoea from low energy availability; bone density assessment and multidisciplinary management, not the combined oral contraceptive pill alone
New mother with failure to establish lactation and persistent amenorrhoea after a major postpartum haemorrhage — Sheehan syndrome; full anterior pituitary workup including morning cortisol

One-line fellowship answer

Amenorrhoea sorts by FIGO HyPO-P (2023) — Type I Hypothalamic, Type II Pituitary, Type III Ovarian, Type IV PCOS — and by the underlying WHO 1973 biochemical logic of Group I (hypogonadotropic, low FSH, low oestradiol), Group II (normogonadotropic — PCOS, outflow obstruction), Group III (hypergonadotropic — POI, Turner, iatrogenic). The investigation ladder: β-hCG → TSH → prolactin (with macroprolactin screen) → day-2/3 FSH/LH/oestradiol → AMH → pelvic ultrasound → MRI pituitary with gadolinium for Group II pituitary, MRI pelvis for outflow-tract anomalies. POI needs karyotype, FMR1, autoimmune screen (21-hydroxylase antibodies), AMH; outflow obstruction needs hymenectomy (imperforate hymen), hysteroscopic adhesiolysis (Asherman), or dilator therapy (MRKH). The FIGO HyPO-P second-tier mechanism mnemonic is GAIN-FIT-PIE (Genetic, Autoimmune, Iatrogenic, Neoplasm, Functional, Infectious/inflammatory, Trauma/vascular, Physiological, Idiopathic, Endocrine).

^[1]

A 16-year-old comes in with her mother because she has never had a period. Her breasts developed normally at 12, she has had cyclical pelvic pain every month for the past year, and the examination reveals a bulging blue-domed membrane at the introitus and a palpable pelvic mass. A 38-year-old executive presents with three months of amenorrhoea after a stressful year, hot flushes, and a prolactin of 28 ng/mL; her FSH is 78 IU/L on two samples. A 28-year-old nulliparous woman has had secondary amenorrhoea and lactation failure since an emergency caesarean hysterectomy four years ago with massive blood loss. None of these women is the same problem, but the FIGO HyPO-P framework sorts them in minutes — outflow-tract obstruction, Type III Ovarian, and Type II Pituitary — and the management ladder follows.^[1]^[3]

Overview and definition

Amenorrhoea is the absence of menses. The clinical sort is by primary (no menses by 15 with secondary sexual characteristics, or by 13 without them) versus secondary (cessation for 3 cycles or 6 months in a previously cycling woman). Oligomenorrhoea is cycles over 35 days or fewer than 8 per year. Each carries a different urgency: primary amenorrhoea with cyclical pain demands an outflow-tract workup on the day; secondary amenorrhoea demands the HPO axis workup within weeks.^[1]^[3]

The 2023 FIGO HyPO-P classification reorganises the half-century-old WHO system into an anatomic axis — Type I Hypothalamic, Type II Pituitary, Type III Ovarian, Type IV PCOS — with a second-tier mechanism (GAIN-FIT-PIE) and a third-tier specific entity. The WHO 1973 three-group biochemical logic (Group I hypogonadotropic, Group II normogonadotropic, Group III hypergonadotropic) remains the exam shorthand because the gonadotropin-oestrogen profile drives treatment choice.^[1]^[2]

The numbers that frame the amenorrhoea workup

3 to 5%Secondary amenorrhoea prevalencePCOS is the single commonest cause

0.1 to 0.3%Primary amenorrhoea prevalenceof reproductive-age women

1–3.5%POI prevalence under 401–2% classic; newer estimates up to 3.5%

1 in 2,500Turner syndrome at birthlive female births; the commonest genetic cause of primary amenorrhoea

over 25 IU/LFSH threshold for POIsingle elevated FSH suffices (ESHRE 2024)

1 in 4,500MRKH prevalencesecond commonest cause of primary amenorrhoea after Turner

^[1] ^[3] ^[10]

References14Show

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[2]ESHRE Capri Workshop Group. Health and fertility in World Health Organization group 2 anovulatory women. Hum Reprod Update, 2012.PMID 22611175
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[8]Gong X, Liu X. Does prior hysteroscopic surgery for intrauterine adhesions impact pregnancy outcomes? A systematic review and meta-analysis of matched comparative studies. J Matern Fetal Neonatal Med, 2025.PMID 40721355
[9]Schöller D, Hölting M, Stefanescu D, et al. Female genital tract congenital malformations and the applicability of the ESHRE/ESGE classification: a systematic retrospective analysis of 920 patients. Arch Gynecol Obstet, 2018.PMID 29549434
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[11]Barbar B, Osman W, Jayasena CN. Synthesizing the latest guideline-based recommendations for the management of female hypogonadism. Arch Endocrinol Metab, 2025.PMID 41337668
[12]Melmed S, Casanueva FF, Hoffman AR, et al. Diagnosis and treatment of hyperprolactinemia: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab, 2011.PMID 21296991
[13]Poulsen BB, Kracht MB, Dueholm M. Intrauterine adhesions after abdominal myomectomy: A systematic review. Eur J Obstet Gynecol Reprod Biol, 2025.PMID 40494172
[15]Oğuz O, Palaoğlu KE, Incir S. Prevalence and re-evaluation of macroprolactinemia in hyperprolactinemic patients: a retrospective study in the Turkish population. Clin Chem Lab Med, 2025.PMID 40183492