Ovulatory Pain

Ovulatory pain (mittelschmerz) is mid-cycle, unilateral lower abdominal or pelvic pain associated with ovulation.

• It affects about 20 to 40 percent of women at some time and begins at ovulation (day 12 to 16 of a 28 day cycle).
• Causes: stretching of the ovarian surface by the maturing follicle, irritation of the peritoneum by follicular fluid and blood at rupture, tubal and uterine contractions.
• It alternates sides or recurs on the same side and may be associated with light spotting from the fall in oestradiol.

Sudden or gradual unilateral lower abdominal pain, dull ache or sharp cramp, lasting a few minutes to 48 hours (usually 6 to 8 hours), mid-cycle, sometimes with slight spotting or increased cervical mucus, mild nausea, and no fever.

• Examination: mild tenderness over the adnexa on the affected side with no peritonism.
• Differential diagnosis: ectopic pregnancy, appendicitis, ruptured or haemorrhagic ovarian cyst, ovarian torsion, pelvic inflammatory disease, endometriosis, urinary tract infection or stone, diverticulitis, irritable bowel syndrome, early pregnancy loss.
• Complications: rarely haemoperitoneum from follicle rupture, especially in women taking anticoagulants; psychological distress from misdiagnosis.

Clinical diagnosis from typical timing in a regular cycle; menstrual and pain diary for 2 to 3 months confirm the relation to ovulation.

• Pregnancy test, urinalysis, full blood count, and transvaginal ultrasound (follicle collapse, small free pelvic fluid) when pain is severe, atypical, or the diagnosis is uncertain.
• Exclude other causes in women with fever, persistent pain, abnormal bleeding, or peritonism.

Supportive: reassurance, heat to the lower abdomen, rest, hydration.

Pharmacological

• NSAIDs: ibuprofen 400 mg every 6 to 8 hours with food, or naproxen 500 mg twice daily, or diclofenac 50 mg three times daily, started at the first sign of pain; paracetamol 1 g every 6 hours.
• Suppression of ovulation if pain is recurrent and disabling: combined oral contraceptive (ethinyloestradiol 20 to 35 microgram with levonorgestrel 150 microgram or norethisterone) taken cyclically or continuously, or medroxyprogesterone acetate depot 150 mg IM every 12 weeks, or etonogestrel implant.

Procedures: none; diagnostic laparoscopy only if pain persists despite suppression and other causes are suspected.

Special groups: women trying to conceive (the pain marks the fertile window; avoid ovulation suppression), anticoagulated women (urgent assessment for bleeding), adolescents (reassurance).

Red flags: severe pain with syncope, hypotension, positive pregnancy test, fever, peritonism, abnormal bleeding.

Follow-up: none if typical; review if the pattern changes or worsens; reassess at 3 months after starting suppressive therapy.