Polymenorrhoea

Polymenorrhoea is regular menstrual cycles that are consistently shorter than 21 days, so that periods come more often than every 3 weeks. It results from a shortened follicular phase (low ovarian reserve, perimenopause), a short luteal phase, anovulatory cycles, thyroid disease, pelvic infection, endometrial polyps and contraceptive effect. It matters because it causes iron deficiency anaemia, reduced fertility and distress, and it can signal underlying disease.

• Risk factors: age above 40 years (perimenopause), thyroid disease, pelvic infection, endometrial polyp, intrauterine device, stress, early menarche.
• A short follicular phase is a common ovulatory cause.
• Ovulation is usually present and may be early.

Women have periods every 14 to 20 days, with normal or increased flow, premenstrual symptoms, and sometimes spotting between periods. Tiredness and breathlessness suggest anaemia.

• Regular short cycles on a menstrual diary.
• Pallor in anaemia; goitre in thyroid disease; cervical or pelvic tenderness in infection.
• Differential diagnosis: perimenopause, luteal phase defect, anovulatory bleeding, intermenstrual bleeding, hypothyroidism, hyperthyroidism, pelvic inflammatory disease, endometrial polyp, adenomyosis, fibroids, contraceptive related bleeding, cervical or endometrial cancer, bleeding disorder.
• Complications: iron deficiency anaemia, reduced quality of life, subfertility, missed work, endometrial hyperplasia, anxiety.

The approach is a menstrual diary, pregnancy test and tests to find the cause.

• Menstrual diary for 3 months; urine or serum hCG; examination of the abdomen, speculum and bimanual pelvic examination.
• Full blood count, ferritin, thyroid stimulating hormone, day 21 progesterone (above 30 nmol/L confirms ovulation), follicle stimulating hormone and oestradiol if age above 40 years.
• High vaginal swab, chlamydia and gonorrhoea tests, cervical screening if due.
• Transvaginal ultrasound for polyps, fibroids and endometrial thickness; hysteroscopy and endometrial sampling if age is above 45 years or bleeding persists.

The principle is to treat the cause, regulate the cycle and correct anaemia.

• Supportive: menstrual diary; reassurance when no cause is found; dietary iron; stress reduction; treatment of partner for sexually transmitted infection; review of intrauterine device.
• Pharmacological: combined oral contraceptive pill with ethinylestradiol 30 micrograms and levonorgestrel 150 micrograms oral once daily for 21 days then 7 days free (or continuous); levonorgestrel intrauterine system 52 mg for 5 years; norethisterone 5 mg oral 8-hourly on days 5 to 26 of the cycle for 3 cycles when oestrogen is contraindicated; tranexamic acid 1 g oral 8-hourly for up to 4 days during bleeding; mefenamic acid 500 mg oral 8-hourly with food during bleeding; ferrous sulphate 200 mg oral 12-hourly for 3 months for anaemia; levothyroxine 50 micrograms oral once daily increased every 4 to 6 weeks for hypothyroidism; infection: ceftriaxone 1 g IM once plus doxycycline 100 mg oral 12-hourly for 14 days plus metronidazole 400 mg oral 12-hourly for 14 days for pelvic inflammatory disease.
• Procedures: hysteroscopic polypectomy; endometrial ablation for heavy bleeding after childbearing; removal of an intrauterine device if it is the cause.
• Special groups: women wishing to conceive have luteal phase assessment and fertility review after 6 months; perimenopausal women prefer the levonorgestrel intrauterine system; women who cannot take oestrogen (migraine with aura, hypertension, smoking above age 35 years) use progestogen-only methods.
• Red flags: heavy bleeding with haemoglobin below 8 g/dL, postcoital bleeding, bleeding after age 45 years that does not settle, pelvic mass, fever with pelvic pain, weight loss.
• Follow-up: review at 3 months with menstrual diary and haemoglobin; endometrial assessment if no response; review at 6 months; annual cervical screening as due.