FFinalistSouthampton · 2027
Obstetrics & gynaecology
AKT · Obstetrics & gynaecology/Menstrual & benign gynaelow yield

Primary dysmenorrhoea

Prostaglandin-mediated painful periods, no pelvic pathology

Overview

Painful menstruation WITHOUT identifiable pelvic pathology, caused by excess endometrial prostaglandins. It begins soon after menarche; the contrast is secondary dysmenorrhoea (endometriosis/adenomyosis/fibroids), which starts later and has other features.

Recognise

  • Crampy suprapubic pain starting just before/with menses, lasting 1–3 days
  • Onset within 6–12 months of menarche; otherwise normal examination
  • May have nausea, headache, back pain

Red flags

  • Pain starting years after menarche, deep dyspareunia, menorrhagia, or an abnormal examination → suspect a SECONDARY cause

Differentials & how to tell them apart

Endometriosissecondary; cyclical pain + deep dyspareunia, later onset, signs on exam/laparoscopy
Adenomyosissecondary; bulky tender uterus, heavy painful periods, older/parous
Pelvic inflammatory disease (gynae)discharge, cervical motion tenderness, not purely cyclical
Fibroidsbulk symptoms, heavy bleeding

Investigations

Clinical; examination normal. Investigate (USS, swabs, laparoscopy) only if features suggest a secondary cause.

Management

NSAIDs first-line (± combined hormonal contraception)

  1. 1NSAIDs first-line (inhibit prostaglandins); add or substitute combined hormonal contraception if also wanted or NSAIDs insufficient; lifestyle (heat, exercise).Gate: Pain starting years after menarche, or with deep dyspareunia/menorrhagia/abnormal exam → investigate for a SECONDARY cause
  2. 2No response / red flags → USS, swabs, consider laparoscopy for endometriosis.
NSAIDs (mefenamic acid, ibuprofen) — first-line — inhibit prostaglandins
Combined hormonal contraception — second-line / if contraception also wanted

Key points

Onset near menarche with a normal examination = primary; later onset with other features = secondary (investigate).

Monitor & prognosis

Symptom response; reassess if new features.

Often improves with age and after childbirth.

Source: NICE CKS Dysmenorrhoea