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Dysmenorrhea: A Merck Manual of Patient Symptoms podcast

Dysmenorrhea is uterine pain around the time of menses. Pain may occur with menses or precede menses by 1 to 3 days. Pain tends to peak 24 h after onset of menses and subside after 2 to 3 days. It is usually sharp but may be cramping, throbbing, or a dull, constant ache; it may radiate to the legs. Headache, nausea, constipation or diarrhea, lower back pain, and urinary frequency are common; vomiting occurs occasionally. Symptoms of premenstrual syndrome may occur during part or all of menses. Sometimes endometrial clots or casts are expelled.

Etiology

Dysmenorrhea can be

• Primary (more common)
• Secondary (due to pelvic abnormalities)

Primary dysmenorrhea: Symptoms cannot be explained by structural gynecologic disorders. Pain is thought to result from uterine contractions and ischemia, probably mediated by prostaglandins and other inflammatory mediators produced in secretory endometrium and possibly associated with prolonged uterine contractions and decreased blood flow to the myometrium. Contributing factors may include passage of menstrual tissue through the cervix, a narrow cervical os, a malpositioned uterus, lack of exercise, and anxiety about menses. It occurs almost invariably in ovulatory cycles. Risk factors for severe symptoms include earlier age at menarche, long or heavy menstrual periods, smoking, and a family history of dysmenorrhea.

Primary dysmenorrhea usually starts during adolescence and tends to lessen with age and after pregnancy.

Secondary dysmenorrhea: Symptoms are due to pelvic abnormalities. Common causes include

• Endometriosis (the most common cause)
• Uterine adenomyosis
• Fibroids

Less common causes include congenital malformations, ovarian cysts and tumors, pelvic inflammatory disease, pelvic congestion, and copper intrauterine devices (IUDs).

In a few women, pain occurs when the uterus attempts to expel tissue through an extremely tight cervical os (secondary to conization, loop electrosurgical excision procedure [LEEP], cryocautery, or thermocautery). Pain occasionally results from a pedunculated submucosal fibroid or an endometrial polyp extruding through the cervix.

Secondary dysmenorrhea usually begins during adulthood unless caused by congenital malformations.

Evaluation

History: History of present illness should cover complete menstrual history, including age at onset of menses, duration and amount of flow, time between menses, variability of timing, and relation of menses to symptoms. Clinicians should also ask about the age at which symptoms began, their nature and severity, factors that relieve or worsen symptoms, degree of disruption of daily life, and presence of pelvic pain unrelated to menses.

Review of systems should include accompanying symptoms such as cyclic nausea, vomiting, bloating, diarrhea, and fatigue. Sexual history should include effect of contraceptives on pain and prior or current history of sexual abuse.

Past medical history should identify known causes, including endometriosis, uterine adenomyosis, or fibroids. Method of contraception should be ascertained, specifically asking about IUD use.

Physical examination: Pelvic examination focuses on detecting causes of secondary dysmenorrhea. The vagina, vulva, and cervix are inspected for lesions and for masses protruding through the cervical os. Structures are palpated to check for a tight cervical os, prolapsed polyp or fibroid, uterine masses, adnexal masses, thickening of the rectovaginal septum, induration of the cul-de-sac, and nodularity of the uterosacral ligament.

Red flags: The following findings are of particular concern:

• New or sudden-onset pain
• Unremitting pain
• Fever
• Vaginal discharge

Interpretation of findings: Red flag findings suggest a cause of pelvic pain other than dysmenorrhea.

Primary dysmenorrhea is suspected if symptoms begin soon after menarche or during adolescence.

Secondary dysmenorrhea is suspected if symptoms begin after adolescence or in patients with known causes, including uterine adenomyosis, fibroids, a tight cervical os, a mass protruding from the cervical os, or, particularly, endometriosis.

Endometriosis is considered in patients with adnexal masses, thickening of the rectovaginal septum, induration of the cul-de-sac, nodularity of the uterosacral ligament, or, occasionally, nonspecific vaginal, vulvar, or cervical lesions.

Testing: Testing aims to exclude structural gynecologic disorders. Most patients should have

• Pregnancy testing
• Pelvic ultrasonography

Intrauterine and ectopic pregnancy are ruled out by pregnancy testing. If pelvic inflammatory disease is suspected, cervical cultures are done.

Pelvic ultrasonography is highly sensitive for pelvic masses such as fibroids, endometriosis, and uterine adenomyosis.

If these tests are inconclusive and symptoms persist, other tests are done. Hysterosalpingography or sonohysterography can be used to identify endometrial polyps, submucous fibroids, or congenital abnormalities. MRI may be used to identify other abnormalities, including congenital abnormalities, or to further define previously identified abnormalities if surgery is planned. If results of all other tests are inconclusive, hysteroscopy or laparoscopy can be done.

Treatment

Underlying disorders are treated. Symptomatic treatment begins with adequate rest and sleep and regular exercise. A low-fat diet and nutritional supplements such as ω-3 fatty acids, flaxseed, magnesium, vitamin E, zinc, and vitamin B₁ are suggested as potentially effective. Women with primary dysmenorrhea are reassured about the absence of structural gynecologic disorders.

If pain persists, drugs, typically prostaglandin inhibitors such as NSAIDs, are tried. NSAIDs are usually started 24 to 48 h before and continued until 1 or 2 days after menses begins. If the NSAID is ineffective, suppression of ovulation with a low-dose estrogen/progestin oral contraceptive is advisable. Other hormonal treatments, such as danazolSome Trade Names
DANOCRINE
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, progestins (eg, levonorgestrelSome Trade Names
MIRENA
PLAN B
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, etonogestrelSome Trade Names
IMPLANON
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, depot medroxyprogesteroneSome Trade Names
PROVERA
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acetate), gonadotropin-releasing hormone agonists, or a progesterone IUD, may decrease dysmenorrheal symptoms.

Periodic adjunctive use of analgesics may be needed. Hypnosis is being evaluated as treatment. Other proposed nondrug therapies, including acupuncture, acupressure, chiropractic therapy, and transcutaneous electrical nerve stimulation, have not been well studied.

For intractable pain of unknown origin, presacral neurectomy and division of the sacrouterine ligaments to interrupt uterine nerves may help.

Key Points

• Most dysmenorrhea is primary.
• Underlying structural pelvic lesions need to be excluded.
• Usually, testing begins with ultrasonography.

Last full review/revision January 2010 by JoAnn V. Pinkerton, MD

Content last modified January 2010