What is the appropriate workup and initial management for dysmenorrhoea, including history, physical examination, laboratory studies, imaging, and first‑line treatment?

Workup for Dysmenorrhoea

Initial Clinical Assessment

Begin with a focused menstrual and pain history to distinguish primary from secondary dysmenorrhoea, as this determines the entire diagnostic and treatment pathway. 1

Key History Elements

• Document pain characteristics: onset relative to menarche, timing within menstrual cycle (pain starting at or shortly after menarche that occurs during the first 48-72 hours of flow suggests primary dysmenorrhoea), severity, and duration 2, 3
• Identify red flags for secondary causes: abnormal uterine bleeding, dyspareunia, noncyclic pelvic pain, changes in pain intensity or duration over time, and infertility 1
• Assess for endometriosis symptoms: progressive worsening of pain, deep dyspareunia, dyschezia, and pain that begins before menstrual flow 4, 1
• Document medication use: including hormonal contraceptives, NSAIDs, and any prior treatments with their effectiveness 5
• Evaluate for Female Athlete Triad risk factors: weight changes, eating patterns, exercise habits, and menstrual irregularities in athletic patients 6, 5

Physical Examination

• Calculate BMI: obesity suggests PCOS-related dysmenorrhoea, while BMI <18.5 kg/m² raises concern for functional hypothalamic amenorrhea 5, 7
• Perform pelvic examination in sexually active patients: assess for cervical motion tenderness, adnexal masses, uterine enlargement (suggesting adenomyosis), nodularity of uterosacral ligaments (suggesting endometriosis), and anatomic abnormalities 1, 7
• Assess for signs of hyperandrogenism: hirsutism, acne, androgenetic alopecia if PCOS is suspected 5

Laboratory Testing

Primary dysmenorrhoea with typical presentation (pain starting at menarche, occurring only during menses, normal examination) requires no laboratory workup. 3, 1

When Laboratory Tests Are Indicated

• Pregnancy test: mandatory first step in any reproductive-age woman with new or changed menstrual symptoms 5, 8
• Hormonal panel if menstrual irregularity coexists: FSH, LH, TSH, prolactin, and estradiol to evaluate for PCOS, thyroid dysfunction, or hyperprolactinemia 5, 8
• Consider testosterone and DHEA-S: if clinical hyperandrogenism is present to screen for PCOS or adrenal pathology 5

Imaging Studies

Transvaginal ultrasonography is indicated when secondary dysmenorrhoea is suspected based on red flag symptoms or abnormal pelvic examination. 1

Ultrasound Indications

• Abnormal pelvic examination findings: adnexal masses, enlarged uterus, or nodularity 1
• Symptoms suggesting endometriosis or adenomyosis: progressive pain, deep dyspareunia, or menorrhagia 4, 1
• Failure to respond to NSAIDs after 6 months: warrants imaging to exclude secondary causes 2
• Assess endometrial thickness: thin endometrium (<5 mm) suggests estrogen deficiency, thick endometrium (>8 mm) suggests chronic anovulation 5

Advanced Imaging

• MRI of pelvis: reserved for cases where ultrasound is inconclusive and adenomyosis or deep infiltrating endometriosis is strongly suspected 6
• Laparoscopy: diagnostic gold standard for endometriosis, indicated only after failed medical management or when imaging suggests significant pathology 2, 1

First-Line Treatment

NSAIDs are the first-line treatment for primary dysmenorrhoea, started at the onset of menses or just before, and continued for the first 2-3 days of flow. 4, 3, 1

NSAID Options

• Ibuprofen, naproxen, mefenamic acid, or indomethacin: all prostaglandin synthetase inhibitors with proven efficacy in reducing menstrual fluid prostaglandins and uterine hyperactivity 2, 9
• Mechanism: these agents inhibit endometrial prostaglandin synthesis, which is the primary pathophysiology of primary dysmenorrhoea 4, 3

Second-Line Treatment

• Hormonal contraceptives (combined oral contraceptives or progestins): indicated when NSAIDs alone are insufficient or when contraception is desired 4, 1
• Mechanism: suppress endometrial growth, reducing menstrual flow volume and prostaglandin production 2, 9
• For endometriosis-related dysmenorrhoea: hormonal contraceptives are first-line treatment 1

Special Considerations and Pitfalls

• Do not perform routine pelvic examination in adolescents who are not sexually active: history alone is sufficient for diagnosing primary dysmenorrhoea in this population 5
• Approximately 10% of patients do not respond to NSAIDs and hormonal contraceptives: these patients require imaging and consideration of laparoscopy to exclude secondary causes 3, 1
• Endometriosis is the most common cause of secondary dysmenorrhoea: maintain high suspicion in patients with progressive symptoms or pain that precedes menstrual flow 4, 1
• Bone density assessment with DXA: indicated in patients with dysmenorrhoea accompanied by amenorrhea ≥6 months, BMI <17.5 kg/m², history of disordered eating, or stress fractures 6, 7
• IUD-associated dysmenorrhoea: responds well to NSAIDs as the mechanism involves increased prostaglandin production 2, 9