Primary dysmenorrhea is menstrual pain associated with menstrual cycles in the absence of pathologic findings. Pain usually begins within 1–2 years after the menarche and may become progressively more severe. The frequency of cases increases up to age 20 and then decreases with both increasing age and parity. Fifty to 75% of women are affected by dysmenorrhea at some time and 5–6% have incapacitating pain.
Primary dysmenorrhea is low, midline, wave-like, cramping pelvic pain often radiating to the back or inner thighs. Cramps may last for 1 or more days and may be associated with nausea, diarrhea, headache, and flushing. The pain is produced by uterine vasoconstriction, anoxia, and sustained contractions mediated by prostaglandins. The pelvic examination is normal between menses; examination during menses may produce discomfort, but there are no pathologic findings.
NSAIDs (ibuprofen, ketoprofen, mefenamic acid, naproxen) and the cyclooxygenase (COX)-2 inhibitor celecoxib are generally helpful. The medication should be started 1–2 days before expected menses. Symptoms can be suppressed with use of combined oral contraceptives, DMPA, etonogestrel subdermal (Nexplanon), or the LNG-IUD. Continuous use of oral contraceptives can be used to suppress menstruation completely and prevent dysmenorrhea. For women who do not wish to use hormonal contraception, other therapies that have shown at least some benefit include local heat; thiamine, 100 mg/day orally; vitamin E, 200 units/day orally from 2 days prior to and for the first 3 days of menses; and high-frequency transcutaneous electrical nerve stimulation.
2. OTHER CATEGORIES OF PELVIC PAIN
Unlike primary dysmenorrhea, other causes of pelvic pain may or may not be associated with the menstrual cycle but are more likely to be associated with pelvic pathology. Conditions such as endometriosis, adenomyosis, fibroids, pelvic inflammatory disease (PID), or other anatomic abnormalities of the pelvic organs, including the bowel or bladder, may present with symptoms during the menstrual cycle or with a more chronic nature.
The history and physical examination may suggest endometriosis, adenomyosis, or fibroids. Other causes include PID, submucous myoma(s), IUD use, cervical stenosis with obstruction, or blind uterine horn (rare). Careful review of associated bowel or bladder symptoms should be done to exclude another pelvic organ source.
Pelvic imaging is useful for diagnosing the presence of uterine fibroids or other anomalies. Adenomyosis (the presence of islands of endometrial tissue in the myometrium) may be detected with ultrasound or MRI. Cervical stenosis may result from procedures done to the cervix, such as loop electrosurgical excision procedure (LEEP) or from an induced abortion. Such stenosis can create crampy pain at the time of expected menses with obstruction of blood flow. Laparoscopy may be used to diagnose endometriosis or other pelvic abnormalities not visualized by imaging.