Dysmenorrhea is one of the most common gynecological symptoms, characterized by pain and a heavy or distended sensation in the lower abdomen before, during, or after menstruation. It may be accompanied by backaches or other discomforts, with severe symptoms potentially affecting daily life and work. Dysmenorrhea is classified into two types: primary dysmenorrhea and secondary dysmenorrhea. Primary dysmenorrhea is idiopathic and not associated with pelvic diseases, accounting for more than 90% of cases. Secondary dysmenorrhea arises from pelvic disorders, as any lesion affecting the nervous system of pelvic organs may result in pain. This section focuses solely on primary dysmenorrhea.
Etiology
The onset of primary dysmenorrhea is primarily associated with increased levels of prostaglandins (PGs) in the endometrium during menstruation. Studies have shown that PGF2α and PGE2 levels in the endometrium and menstrual blood are significantly higher in patients with dysmenorrhea compared to normal individuals. Elevated PGF2α levels are predominantly responsible for the condition. During the menstrual cycle, prostaglandin concentrations in the secretory-phase endometrium are higher than those in the proliferative phase. During menstruation, the breakdown of endometrial cells by lysosomal enzymes leads to a sharp increase in PGF2α and PGE2 levels. Elevated PGF2α levels result in excessive uterine smooth muscle contraction and vasoconstriction, leading to uterine ischemia and hypoxia, which are associated with menstrual pain. Circulating prostaglandins can also induce cardiovascular and gastrointestinal symptoms.
Other factors, such as increased levels of vasopressin, interleukins, endogenous oxytocin, and β-endorphins, are also associated with primary dysmenorrhea. Additionally, psychological and neurological factors may influence dysmenorrhea, with individual pain perception influenced by pain thresholds.
Cervical stenosis may also contribute to menstrual pain. Proliferative-phase endometrial tissue in anovulatory cycles contains low levels of prostaglandins, which generally do not provoke dysmenorrhea.
Clinical Presentation
The main characteristics include:
Primary dysmenorrhea is most common during adolescence, typically emerging 1–2 years after menarche.
Pain usually begins with the onset of menstruation, or as early as 12 hours before menstruation starts, peaking during the first day of the menstrual cycle and subsiding after 2–3 days. The pain is often cramp-like, localized to the suprapubic lower abdomen, and may radiate to the lumbosacral region and inner thighs.
Symptoms may include nausea, vomiting, diarrhea, dizziness, and fatigue. Severe cases may involve pallor and cold sweats.
Gynecological examinations typically reveal no abnormalities.
Diagnosis and Differential Diagnosis
Diagnosis is based on menstrual-period pelvic pain, the absence of positive findings in gynecological examinations, and the exclusion of organic abnormalities via ultrasound. Differential diagnosis involves distinguishing primary dysmenorrhea from secondary dysmenorrhea caused by conditions such as endometriosis, adenomyosis, or pelvic inflammatory disease (PID). Secondary dysmenorrhea usually develops several years after menarche, is often accompanied by a history of gynecological disorders or intrauterine device (IUD) placement, and features abnormalities upon gynecological examination. Laparoscopy may be required for clarification if necessary.
Treatment
The primary goal is to alleviate pain and associated symptoms.
General Treatment
Psychological counseling is important to explain that mild discomfort during menstruation is a physiological response. Reducing tension and worry may lessen pain. Adequate rest and sleep, regular yet moderate exercise, cessation of smoking, local heat therapy, behavioral interventions, and dietary adjustments are common methods to relieve dysmenorrhea. Medication may be used if the pain is intolerable.
Pharmacological Treatment
Prostaglandin Synthase Inhibitors
These drugs reduce prostaglandin production by inhibiting prostaglandin synthase activity, thereby preventing excessive uterine contraction and cramping, which alleviates or eliminates pain. The efficacy rate is approximately 80%. The optimal time for administration is at the onset of menstruation, with treatment typically lasting 2–3 days. Common agents include ibuprofen, ketoprofen, and naproxen. For example, ibuprofen is administered at 200 mg per dose, 3–4 times a day.
Oral Contraceptives
By suppressing ovulation, these medications reduce prostaglandin concentrations in menstrual blood, relieving dysmenorrhea. They are particularly suitable for patients with irregular menstruation, heavy menstrual flow, or who require contraception. The efficacy rate exceeds 90%.
Surgical Treatment
Cervical dilation involves mechanically widening the cervical canal to facilitate menstrual flow, reduce intrauterine pressure, and alleviate pain. This method is appropriate for married women with cervical stenosis.