Ovulatory Dysfunction AUB-O Management
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Direct answer
AUB-O is the FIGO category for abnormal uterine bleeding caused by ovulatory dysfunction, in which the woman fails to ovulate and oestrogen acts unopposed on the endometrium. Because no corpus luteum forms, there is no progesterone phase, and the endometrium sheds irregularly. Management controls the bleeding with cyclical progestogens and treats the underlying cause, such as PCOS, thyroid disease or hyperprolactinaemia.
What you must remember
- Classification: AUB-O is the ovulatory category of the FIGO system, distinct from the structural PALM groups such as polyps, adenomyosis and leiomyomas.
- Pathophysiology: Without ovulation there is no secretory phase, so unopposed oestrogen drives proliferation and the endometrium breaks down irregularly.
- Common causes: Polycystic ovary syndrome, hyperprolactinaemia, thyroid dysfunction, extremes of body weight, stress and premature ovarian insufficiency.
- Adolescent pattern: Anovulatory cycles are physiologically common in the first years after menarche, so management is often conservative unless bleeding is heavy or persistent.
- Acute bleeding: Heavy bleeding may need admission, haemodynamic support, correction of anaemia and high-dose hormonal therapy.
- Cyclical progestogen: Medroxyprogesterone acetate for 10 to 14 days in each cycle produces a controlled withdrawal bleed and protects against hyperplasia.
- Investigation: Pregnancy, thyroid function, prolactin and androgens are assessed, and the endometrium is sampled when risk factors are present.
A stepwise approach to AUB-O
A woman presents with irregular heavy bleeding and no obvious structural cause on examination. The steps below follow the usual order, from stabilising her to choosing a long-term regimen.
- Stabilise first: Assess haemodynamic status and haemoglobin, and treat significant anaemia before starting hormonal therapy.
- Exclude pregnancy and structural disease: Check beta-hCG and perform imaging to exclude fibroids, polyps and pregnancy-related causes.
- Look for a systemic cause: Measure TSH, prolactin and androgens, looking especially for PCOS, hyperprolactinaemia and thyroid disease.
- Sample the endometrium when indicated: Biopsy is advised for women aged 45 years and above, or for younger women with obesity, unopposed oestrogen exposure, persistent bleeding or failed medical therapy.
- Choose a cyclical progestogen: Medroxyprogesterone acetate for 10 to 14 days each cycle reduces bleeding and protects the endometrium, and a levonorgestrel intrauterine system suits women who also want contraception.
- Consider combined oral contraceptives: In women not planning pregnancy, cyclical combined oral contraception regularises cycles and controls bleeding, once contraindications are excluded.
- Treat the cause and review: Manage PCOS, thyroid disease or prolactin excess specifically, and reassess the bleeding pattern after a few cycles.
Where the exam tries to catch you
Vignettes about anovulatory bleeding usually test the sequence of investigation and the role of progestogen.
- Trap: Starting a progestogen without a pregnancy test. Correct: Beta-hCG comes first, because pregnancy must be excluded before any hormonal treatment is started.
- Trap: Adding oestrogen alone to stop anovulatory bleeding. Correct: Unopposed oestrogen is the cause of the endometrial overgrowth, so a progestogen must be given to protect against hyperplasia.
- Trap: Attributing all anovulation to obesity. Correct: PCOS, hyperprolactinaemia and thyroid disease are specific, treatable causes that must be excluded.
- Trap: Investigating every adolescent with irregular periods as malignant. Correct: Adolescent anovulation is common and often self-limiting, so investigation is driven by severity and persistence.
Frequently asked questions
What is AUB-O in the FIGO classification?
AUB-O is the FIGO category for abnormal uterine bleeding caused by ovulatory dysfunction. It sits within the PALM-COEIN system, alongside structural causes such as polyps, adenomyosis and leiomyomas and other non-structural categories.
Which progestogen regimen is used for AUB-O bleeding control?
Medroxyprogesterone acetate given for 10 to 14 days in each cycle is a common cyclical regimen for AUB-O. It produces a controlled withdrawal bleed and protects the endometrium against unopposed oestrogen.
When should a woman with AUB-O undergo endometrial sampling?
Endometrial sampling is advised for women aged 45 years and above with abnormal uterine bleeding. Younger women with obesity, unopposed oestrogen exposure, persistent bleeding or failed medical therapy also need sampling to exclude hyperplasia and carcinoma.
Which endocrine tests are essential in ovulatory dysfunction?
TSH and prolactin are essential tests in ovulatory dysfunction, with androgen levels added where PCOS is suspected. Beta-hCG is also needed to exclude pregnancy, because thyroid disease and hyperprolactinaemia are treatable causes of anovulation.
Can combined oral contraceptives treat AUB-O?
Cyclical combined oral contraceptives are an effective option for AUB-O in women who do not wish to conceive, because they regulate cycles and control bleeding. Contraindications such as hypertension, migraine with aura or thrombotic risk must be excluded first.