Oligomenorrhoea

Oligomenorrhoea is infrequent menstruation, with cycles longer than 35 days, or fewer than 9 periods in a year. It results from irregular or absent ovulation due to polycystic ovary syndrome, thyroid disease, hyperprolactinaemia, hypothalamic causes (weight loss, stress, exercise), perimenopause and early ovarian insufficiency. It is common in women of reproductive age, and matters because of its link with infertility, endometrial hyperplasia from unopposed oestrogen, metabolic disease and bone loss.

• Risk factors: obesity, family history of polycystic ovary syndrome, low body weight, intense exercise, thyroid disease, perimenopause, stress, some drugs (antipsychotics, antiepileptics).
• Cycles of 35 to 90 days, with periods at least 3 times a year, are oligomenorrhoea; longer gaps are amenorrhoea.
• Endometrial protection is needed when periods are very infrequent.

Women report infrequent periods that may be heavy when they occur, with signs of the cause: hirsutism, acne and weight gain (polycystic ovary syndrome), hot flushes (perimenopause or ovarian insufficiency), galactorrhoea (hyperprolactinaemia), weight loss or cold intolerance (hypothalamic or thyroid disease).

• Hirsutism score, acne, acanthosis nigricans, body mass index and waist circumference.
• Normal pelvic examination in most.
• Differential diagnosis: polycystic ovary syndrome, hypothyroidism, hyperthyroidism, hyperprolactinaemia, hypothalamic amenorrhoea, perimenopause, premature ovarian insufficiency, contraceptive effect, pregnancy, ovarian or adrenal tumour, Cushing syndrome, non classic congenital adrenal hyperplasia.
• Complications: infertility, endometrial hyperplasia and cancer, type 2 diabetes, dyslipidaemia, cardiovascular disease, low bone density, depression.

The approach is to exclude pregnancy and to look for the endocrine cause.

• Urine or serum hCG; thyroid stimulating hormone, prolactin, follicle stimulating hormone, luteinising hormone, oestradiol; total testosterone, sex hormone binding globulin, 17-hydroxyprogesterone if hirsute.
• Pelvic ultrasound (12 or more follicles of 2 to 9 mm in an ovary, or ovarian volume above 10 mL, supports polycystic ovary syndrome; endometrial thickness).
• Fasting glucose or oral glucose tolerance test (75 g), lipid profile, blood pressure.
• Endometrial sampling or hysteroscopy if the endometrium is thick (above 12 mm) or there is abnormal bleeding with age above 45 years.

The principle is to treat the cause, regulate cycles to protect the endometrium, and support fertility if wanted.

• Supportive: weight loss of 5 to 10 percent in overweight women, with a balanced diet and 150 minutes of moderate exercise weekly; weight gain and reduced exercise if underweight; stress management; stop smoking; counselling about fertility and cycle patterns.
• Pharmacological: polycystic ovary syndrome: combined oral contraceptive pill with ethinylestradiol 30 micrograms and levonorgestrel 150 micrograms oral once daily for 21 days then 7 days free (or continuous in selected women); medroxyprogesterone 10 mg oral once daily for 10 to 14 days every 1 to 3 months for women who cannot use oestrogen; metformin 500 mg oral once daily increased weekly to 500 mg 3 times daily (maximum 2000 mg daily) for insulin resistance; hirsutism: spironolactone 50 mg oral 12-hourly increased to 100 mg 12-hourly with reliable contraception; fertility: letrozole 2.5 mg oral once daily on days 3 to 7, increased by 2.5 mg each cycle to 7.5 mg, or clomifene 50 mg oral once daily on days 2 to 6, increased to 100 and 150 mg; hypothyroidism: levothyroxine 50 micrograms oral once daily increased every 4 to 6 weeks; hyperprolactinaemia: cabergoline 0.25 mg oral twice weekly increased to a maximum of 1 mg twice weekly; perimenopause: levonorgestrel intrauterine system 52 mg for 5 years or the combined pill.
• Procedures: laparoscopic ovarian drilling for polycystic ovary syndrome resistant to letrozole and clomifene; endometrial sampling for thickened endometrium.
• Special groups: women wishing to conceive stop the combined pill and spironolactone and take folic acid 400 micrograms oral daily from 3 months before conception; women with polycystic ovary syndrome and diabetes receive metformin and glucose monitoring; adolescents with irregular cycles in the first 2 years after menarche are reassured and monitored.
• Red flags: endometrial thickness above 12 mm, bleeding after months of amenorrhoea with heavy loss, rapid virilisation, galactorrhoea with visual loss, weight loss with fatigue, postmenopausal bleeding.
• Follow-up: review at 3 months; menstrual diary; yearly screening for diabetes, lipids and blood pressure in polycystic ovary syndrome; endometrial assessment if fewer than 3 periods a year; fertility review after 6 months of attempts.