Dysmenorrhoea

Dysmenorrhoea is painful menstruation, one of the commonest gynaecological complaints affecting women of reproductive age.

It is classified into primary and secondary dysmenorrhoea. Primary dysmenorrhoea is menstrual pain occurring in the absence of identifiable underlying pelvic pathology, reflecting a primary disorder of excessive prostaglandin-mediated uterine contraction.

Secondary dysmenorrhoea is menstrual pain resulting from an identifiable underlying pelvic pathology, most commonly endometriosis or adenomyosis.

Accurate clinical distinction between these two categories, guided substantially by the specific pattern of onset, is essential to appropriately directing diagnostic evaluation and management.

Pathophysiology and classification

• Primary dysmenorrhoea reflects excessive endometrial prostaglandin production (particularly prostaglandin F2-alpha) during menstruation. This drives increased, often excessive myometrial contraction and associated uterine ischaemia, producing the characteristic cramping pelvic pain.
• Symptom onset characteristically occurs shortly after menarche, once ovulatory menstrual cycles become established. This prostaglandin-mediated mechanism depends on the hormonal changes of an ovulatory cycle.
• Secondary dysmenorrhoea reflects an identifiable underlying structural or pathological cause, most commonly endometriosis or adenomyosis. Less common causes are uterine fibroids and pelvic inflammatory disease and its sequelae.
• An intrauterine contraceptive device has a recognised, direct association with secondary dysmenorrhoea.
• The characteristic pattern of onset provides an essential diagnostic clue distinguishing these two categories. Primary dysmenorrhoea typically presents relatively soon after menarche.
• Secondary dysmenorrhoea characteristically presents later, often years after menarche, with new onset or a significant change in the pattern or severity of previously typical menstrual pain. The woman previously had unremarkable or different menstrual pain characteristics. This reflects the development of the underlying structural or pathological process over this period.

• Primary dysmenorrhoea presents with crampy, spasmodic lower abdominal or pelvic pain. It typically begins shortly before or at the onset of menstrual flow and lasts one to three days.
• It is often accompanied by nausea, diarrhoea, fatigue, and headache, reflecting the broader, systemic effects of circulating prostaglandins. Pain is generally most severe during the earlier days of menstrual flow and improves as flow diminishes.
• Secondary dysmenorrhoea presents with pain that may extend beyond the characteristic timing of primary dysmenorrhoea. It sometimes begins before menstruation and persists throughout or beyond the menstrual period.
• Associated features often provide further diagnostic guidance toward the underlying cause: deep dyspareunia and infertility with endometriosis, or heavy menstrual bleeding with adenomyosis or fibroids.
• Red flag features warrant specific consideration of secondary dysmenorrhoea and correspondingly more full diagnostic evaluation. They are new onset dysmenorrhoea after age twenty-five, a significant change in the previously established pattern or severity of menstrual pain, and pain not responding adequately to standard first-line treatment.
• Further red flags are associated heavy menstrual bleeding, intermenstrual bleeding, deep dyspareunia, or infertility, and any abnormal finding on pelvic examination.
• The substantial, frequently significant impact on quality of life, education, and occupational function warrants proactive, sensitive clinical attention and effective management. This common condition can produce substantial, cumulative disability across the reproductive years if inadequately addressed.

• Diagnosis of primary dysmenorrhoea is established clinically, based on the characteristic pattern and timing of symptoms, together with a normal pelvic examination. No routine further investigation is needed in a straightforward, typical presentation without any red flag feature.
• Where any red flag feature is present, or where the clinical pattern suggests secondary dysmenorrhoea, further evaluation directed at identifying the specific underlying cause is warranted. This includes pelvic examination and pelvic ultrasound (screening for fibroids, adenomyosis, or an adnexal mass).
• Where clinically indicated based on the specific presentation, further, more specific investigation is warranted, including diagnostic laparoscopy for suspected endometriosis. Follow the detailed diagnostic principles addressed under the relevant individual conditions.
• Screening for sexually transmitted infection and assessment for pelvic inflammatory disease should be considered where relevant to the specific clinical context and risk factors present.

• Nonsteroidal anti-inflammatory drugs are first-line, highly effective treatment for primary dysmenorrhoea, directly targeting the underlying prostaglandin-mediated pathophysiology.
• Ideally initiate treatment at or just before the anticipated onset of menstrual pain. Continue it regularly through the first several days of the cycle for optimal effectiveness, rather than reserving it for use only once pain has already become established.
• Combined hormonal contraception is a further, effective treatment option for primary dysmenorrhoea. It works through suppression of ovulation and associated reduction in endometrial prostaglandin production.
• It is particularly relevant where contraception is also desired, or where nonsteroidal anti-inflammatory drug treatment alone provides inadequate symptomatic control.
• General supportive measures may provide additional, adjunctive symptomatic benefit alongside the primary pharmacological treatment approaches. They include local heat application, regular exercise, and, for some women, dietary or lifestyle modification.
• Management of secondary dysmenorrhoea is directed at the specific, identified underlying cause, following the established principles for endometriosis, adenomyosis, and the other relevant specific conditions.
• Symptomatic pain management (nonsteroidal anti-inflammatory drugs and, where appropriate, hormonal treatment) is an important, adjunctive component alongside definitive treatment of the underlying cause.
• Referral for specialist gynaecological assessment is appropriate where primary dysmenorrhoea does not respond adequately to an appropriate trial of first-line treatment, or where any red flag feature suggesting secondary dysmenorrhoea is present. This is directly relevant to identifying and appropriately treating any underlying, contributing pathology.
• Full patient education underpins effective management of this extremely common, though frequently significantly impactful, condition. It covers the underlying mechanism and expected pattern of primary dysmenorrhoea, and clear, practical guidance on optimal, timely use of first-line treatment.
• Refer proactively where treatment response is inadequate or red flag features develop.