Dysmenorrhea
Dysmenorrhea is pelvic pain during a menstrual period.
About three fourths of women with dysmenorrhea have primary dysmenorrhea, for which no cause can be identified. The rest have secondary dysmenorrhea, for which a cause is identified.
Primary dysmenorrhea may affect more than 50% of women, usually starting during adolescence. In about 5 to 15%, primary dysmenorrhea is sometimes severe, interfering with daily activities and resulting in absence from school or work. Primary dysmenorrhea may become less severe with age and after pregnancy.
In primary dysmenorrhea, the pain occurs only during menstrual cycles in which an egg is released. The pain is thought to result from prostaglandins released during menstruation. Prostaglandins are hormonelike substances that cause the uterus to contract, reduce the blood supply to the uterus, and increase the sensitivity of nerve endings in the uterus to pain. Women who have primary dysmenorrhea have higher levels of prostaglandins.
Common causes of secondary dysmenorrhea include endometriosis, fibroids, adenomyosis, pelvic congestion syndrome, and pelvic infection. In a few women, the pain results from passage of menstrual blood through a narrow cervix (cervical stenosis). A narrow cervix may be present at birth or result from removal of polyps or treatment of a precancerous condition (dysplasia) or cancer of the cervix. Abdominal pain due to other disorders, such as inflammation of the fallopian tubes or abnormal bands of fibrous tissue (adhesions) between structures in the abdomen, may be worse during a menstrual period.
 See the sidebar Adenomyosis: Noncancerous Growth of the Uterus.
Symptoms and Diagnosis
Pain occurs in the lower abdomen and may extend to the lower back or legs. The pain is usually crampy and comes and goes, but it may be a dull, constant ache. Usually, the pain starts shortly before or during the menstrual period, peaks after 24 hours, and subsides after 2 days. Other common symptoms include headache, nausea, constipation, diarrhea, and an urge to urinate frequently. Occasionally, vomiting occurs. Premenstrual irritability, nervousness, depression, and abdominal bloating may persist during part or all of the menstrual period.
Diagnosis is based on symptoms and the results of a physical examination. To identify possible causes (such as fibroids), doctors may examine the abdominal cavity using a viewing tube (laparoscope) inserted through a small incision just below the navel. They may examine the interior of the uterus using a similar tube (hysteroscope) inserted through the vagina and cervix. Other procedures may include dilation and curettage (D and C) and hysterosalpingography (see Section 22, Chapter 242 and Section 22, Chapter 242).
Treatment
Nonsteroidal anti-inflammatory drugs (NSAIDs) usually relieve pain effectively. NSAIDs may be more effective if started 1 or 2 days before a menstrual period begins and continued for 1 or 2 days after it begins. An antiemetic drug may relieve nausea and vomiting, but these symptoms usually disappear without treatment as the pain subsides. Getting enough rest and sleep and exercising regularly may also help relieve symptoms.
If the pain continues to interfere with daily activities, oral contraceptives that contain estrogen in a low dose plus a progestin may be prescribed to suppress the release of eggs from the ovaries (ovulation). If these treatments are ineffective, procedures to identify the cause of the pain may be performed.
When dysmenorrhea results from another disorder, that disorder is treated if possible. A narrow cervical canal can be widened surgically. However, this operation usually relieves the pain only temporarily. If needed, fibroids or misplaced endometrial tissue (due to endometriosis) is surgically removed.
When other treatments are ineffective and the pain is severe, the nerves to the uterus may be cut surgically. However, this operation occasionally injures other pelvic organs, such as the ureters. Alternatively, hypnosis or acupuncture may be tried.
See the sidebar What Is Pelvic Congestion Syndrome?
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