II. Epidemiology
- Onset occurs within 6 to 12 months of Menarche (may occur as long as 2 years from Menarche in some women)
- Prevalence peaks around age 20 years
- Lifetime Prevalence of severe Dysmenorrhea: 50-60%
- Women incapacitated for 1-3 days of each cycle: 10%
III. Pathophysiology
- No clear pelvic pathology
- Contrast with Secondary Dysmenorrhea in which an underlying organic etiology is identified
- Hormonal and inflammatory level increases with no clear pelvic pathology
- Increased Leukotriene levels
- Uterine hyperactivity with increased uterine contractility and cramping
- Increased myometrial resting tone >10 mmHg
- Increased contractile myometrial pressure >120 mmHg
- Increased frequency of uterine contractions
- Dysrhythmia of uterine contractions
- Increased Prostaglandin levels
- Increase in enzyme Prostaglandin Synthetase
- Increased Prostaglandins result in Vasoconstriction
- Prostaglandin mediated nerve terminal Hypersensitivity with high intensity contractions
- Vasopressin-mediated contractions
- Reduces uterine Blood Flow via Vasoconstriction
- May result in ischemic pain from uterine Hypoxia (uterine Angina)
IV. Symptoms
- See Dysmenorrhea
- Onset occurs within 6 to 12 months of Menarche and recurrs with each Menstrual Cycle
V. Examination
- See Dysmenorrhea
- Normal pelvic examination
VI. Differential Diagnosis
VII. Labs
VIII. Precautions
- Primary Dysmenorrhea is a diagnosis of exclusion
- Exclude Secondary Dysmenorrhea causes (at minimum: pregnancy, Urinary Tract Infection and Sexually Transmitted Infection
- Older women without prior history of Dysmenorrhea should be assumed to have Secondary Dysmenorrhea until thorough evaluation is completed
- In young women, Secondary Dysmenorrhea still accounts for 10% of cases (especially due to Endometriosis)
IX. Management
- See Dysmenorrhea