Dysmenorrhea - Primary

Definition

Primary dysmenorrhea is recurrent, crampy lower abdominal pain occurring during menstruation without identifiable pelvic pathology, typically beginning within a few years of menarche.

Epidemiology

• Very common in adolescent and young adult women, affecting 50–90% globally.
• Pain usually begins within 6–12 months of menarche.
• Severity may decrease with age or after childbirth.
• Leading cause of school and work absenteeism among adolescents.
• Family history increases risk.

Etiology

• Excessive production of uterine prostaglandins (PGF2α and PGE2) leading to increased uterine contractions and ischemia.
• Hypercontractility of the myometrium.
• Increased sensitivity to pain due to central or peripheral mechanisms.
• No underlying structural abnormality (distinguishes it from secondary dysmenorrhea).

Pathophysiology

• During menstruation, endometrial cells release prostaglandins causing uterine smooth muscle contractions.
• Excessive prostaglandin production leads to ischemia and pain.
• Vasopressin may contribute to uterine hypercontractility.
• Central sensitization may enhance perception of pain in some individuals.
• Self-limited and resolves as prostaglandin levels decrease with menstrual flow.