To diagnose primary dysmenorrhea, it is necessary to clinically rule out underlying pelvic pathology and confirm the cyclic nature of the pain. During the pelvic examination, the size, shape, and mobility of the uterus; the size and tenderness of adnexal structures; and the nodularity or fibrosis of uterosacral ligaments or rectovaginal septum should be assessed. NAAT for gonorrhea and chlamydia and if relevant, CBC and ESR, help rule out endometritis and subacute PID. Pelvic ultrasound should be performed if symptoms do not resolve with NSAIDs. If no abnormalities are found, a tentative diagnosis of primary dysmenorrhea can be established. Laparoscopy is not necessary at this point.
Table 16.3 Differential Diagnosis of Chronic Pelvic Pain
Prostaglandin synthase inhibitors, also called nonsteroidal anti-inﬂammatory agents, are effective for the treatment of primary dysmenorrhea (38). The inhibitors should be taken up to 1 to 3 days before or, if menses are irregular, at the first onset of even minimal pain or bleeding and then continuously every 6 to 8 hours to prevent reformation of prostaglandin by-products. The medication should be taken for the first few days of menstrual ﬂow.
Figure 16.1 The biosynthesis and metabolism of prostaglandins and thromboxane derived from arachidonic acid. (From Chaudhuri G. Physiologic aspects of prostaglandins and leukotrienes. Semin Reprod Endocrinol 1985;3:219, with permission.)
A 4-to 6-month course of therapy is warranted to determine whether the patient will respond to treatment. Changes in dosages and types of NSAIDs should be attempted if initial treatment is not successful. The medication may be contraindicated in patients with gastrointestinal ulcers or bronchospastic hypersensitivity to aspirin. Side effects are usually mild and include nausea, dyspepsia, diarrhea, and occasionally fatigue.
Hormonal contraceptives are indicated for primary dysmenorrhea unresponsive to NSAIDs or for patients with primary dysmenorrhea who have no contraindications to hormonal contraceptive and who desire contraception. Hormonal contraceptive agents (such as combined estrogen and progestin) or progesterone only oral contraceptives (either cyclic or continuous regimens), transdermal patch, vaginal ring, injectable progestin preparations, or levonorgestrel-releasing intrauterine devices are more effective than placebo alone and result in less absence from work or school (39). Continuous or extended cycle combined oral contraceptive pills are just as efficacious for this pain syndrome (40). Hormonal contraceptives inhibit ovulation, decrease endometrial proliferation, and create an endocrine milieu similar to the early proliferative phase of the menstrual cycle, when prostaglandin levels are lowest. Decreased prostaglandin levels result in less uterine cramping.
If the patient does not respond to this regimen, hydrocodone or codeine may be added for 2 to 3 days per month; before addition of the narcotic medication, psychological factors should be evaluated, and diagnostic laparoscopy to rule out pathology should be considered.