Midcycle Bleeding

Midcycle bleeding is light spotting around the time of ovulation, usually on days 12 to 16 of the cycle, caused by a short fall in oestrogen after the luteinising hormone surge. It occurs in some ovulating women, lasts 1 to 2 days, and is normal. It matters because it can be mistaken for a short cycle or for disease, and because persistent or heavy midcycle bleeding needs examination for cervical and uterine causes.

• Risk factors: ovulatory cycles, low oestrogen dose pills, intrauterine device, cervical ectropion, endometrial polyp, chlamydia infection.
• Often accompanied by mittelschmerz and clear stretchy mucus.
• Spotting repeated each cycle is typical for ovulation.

Women have light pink or brown spotting for 1 to 2 days at midcycle, with or without one-sided lower abdominal pain, clear stretchy cervical mucus and a rise in libido. The examination is normal.

• Spotting only, not enough to need a pad.
• Regular timing 12 to 16 days after the last period.
• Differential diagnosis: normal ovulation spotting, early pregnancy implantation bleeding, cervical ectropion or polyp, chlamydia cervicitis, endometrial polyp, hormonal contraceptive breakthrough bleeding, intrauterine device effect, endometrial hyperplasia, cervical cancer, thyroid disease.
• Complications: anxiety, anaemia if heavy, delayed diagnosis of a cervical or uterine lesion, unplanned pregnancy from misread fertile window.

The diagnosis is clinical, with tests when bleeding persists or looks abnormal.

• Menstrual diary showing bleeding timed with ovulation for 2 to 3 cycles; urine hCG.
• Speculum examination, chlamydia and gonorrhoea tests, cervical screening if due.
• Transvaginal ultrasound if bleeding is heavy, lasts more than 3 days or persists for 3 or more cycles.
• Midluteal progesterone above 30 nmol/L to confirm ovulation if the timing is unclear.

The principle is reassurance when bleeding is typical, and investigation and treatment when it is not.

• Supportive: reassurance that ovulation spotting is normal; menstrual diary; panty liner if needed; condoms or contraception when pregnancy is not wanted.
• Pharmacological: combined oral contraceptive pill with ethinylestradiol 30 micrograms and levonorgestrel 150 micrograms oral once daily for 21 days then 7 days free, to suppress ovulation if bleeding is bothersome; tranexamic acid 1 g oral 8-hourly for 2 to 4 days if bleeding is heavier; chlamydia: doxycycline 100 mg oral 12-hourly for 7 days; gonorrhoea: ceftriaxone 1 g IM as a single dose; mefenamic acid 500 mg oral 8-hourly with food for 3 days for associated pain.
• Procedures: hysteroscopic polypectomy; removal of a cervical polyp.
• Special groups: women who cannot use oestrogen (migraine with aura, hypertension, previous clot, smoking above age 35 years) use levonorgestrel 30 micrograms oral once daily or the levonorgestrel intrauterine system; women wishing to conceive use the spotting as a marker of the fertile window.
• Red flags: heavy bleeding, bleeding after intercourse, pain with fever, positive pregnancy test, persistent bleeding beyond 3 cycles, age above 45 years, abnormal cervix.
• Follow-up: review at 3 months with diary; investigate further if bleeding persists after reassurance; cervical screening as due.