Reproductive health

Menstrual cramps

Dysmenorrhea (menstrual cramps) is one of the most common problems suffered by women of childbearing age. It's estimated that between 30 and 50 percent of women suffer from pain during their menstrual period, and of these, 15 percent would describe their menstrual cramps as severe. Some women's menstrual cramps are so severe, they must curtail their normal activities—any movement or activity is too painful.

Menstrual cramps should not be confused with the discomfort experienced during premenstrual syndrome (PMS), although the symptoms of both disorders can sometimes be experienced as a continual process. PMS, characterized by a combination of emotional, physical, psychological, and mood disturbances, occurs after a woman's ovulation and normally ends with the onset of her menstrual flow. Menstrual cramps usually occur shortly before or during the first few days of a woman's menstrual period, peaking within 24 hours after onset, and subsiding again after about a day or two. Cramps may be barely noticeable, feeling like a light heaviness in the belly, or they may be so painful, they may interfere with a woman's normal activities for several days. In addition to abdominal pain, cramp sufferers also experience backache, pinching and pain sensations in the inner thighs, bloating, nausea, vomiting, diarrhea, constipation, faintness, dizziness, fatigue, and headaches.¹

The normal menstrual cycle

To better understand why painful menstruation occurs, it's important to look at the normal menstrual cycle and see how it functions.

Menstruation refers to the shedding of the endometrium, or uterine lining. Every month, in anticipation of housing and nourishing a fertilized egg, the uterus prepares a thick, blood-rich cushion. If fertilization doesn't occur and a fertilized egg doesn't implant in the uterus, this extra blood and tissue are not needed by the body; the uterus then cleanses itself by shedding this lining so that a fresh buildup can occur the following month, in anticipation of a possible pregnancy.

The buildup and shedding of the uterine lining is a complex mechanism controlled by the fluctuations in a woman's hormone levels. Each month, the pituitary gland releases follicle stimulating hormones (FSH) and luteinizing hormones (LH) into the bloodstream where they can be carried to the ovaries, the tiny sacs that contain all the eggs a woman will ever have. Eggs in the ovaries exist in an inactive form called follicles. During each menstrual cycle, the FSH and LH from the pituitary gland cause one follicle to ripen, and a normal ovum (egg) is released for fertilization. As a normal part of this process, the follicle begins to produce the hormones estrogen and progesterone.

In addition to preparing the egg for fertilization, estrogen and progesterone stimulate the lining of the uterus. During the first two weeks following a woman's menstrual cycle, estrogen stimulates the rebuilding of the uterine lining. The inner mucus layer of endometrial glands start to grow long and through an increase in the number of blood vessels as well as the production of a mesh of fibers that interconnect throughout the lining, the endometrium thickens.

By mid-cycle (day 14), the lining of the uterus has increased three times in thickness and has a greatly increased blood supply. After day 14, ovulation occurs: the egg travels through the fallopian tube to the uterus. After mid-cycle, the graafian follicle that produced the egg for that month is further stimulated by LH and changes into a corpus luteum, a yellow body that secretes progesterone. Progesterone affects the uterine lining by causing a coiling of the blood vessels of the lining, which itself becomes swollen and secretes a thick mucus.

If fertilization occurs, the egg will implant itself in the uterine wall and the corpus luteum will continue to secrete progesterone. However, if fertilization does not occur, the corpus luteum begins to deteriorate and progesterone levels decrease. The lining of the uterus breaks down and menstruation begins.

During the breakdown of the uterine lining, molecular compounds called prostaglandins are released. Prostaglandins and in particular, prostaglandin F2alpha (PGF2alpha), cause the muscles of the uterus to contract, thereby constricting the blood supply to the endometrium. This contraction interferes with the oxygenation of endometrial tissue which, in turn, breaks down and dies. After the death of this tissue, uterine contractions literally squeeze the old endometrial tissue through the cervix and out of the body by way of the vagina. The pain of cramps is intensified when clots or pieces of bloody tissue from the lining of the uterus pass through the cervix, especially if a woman's cervical canal is narrow.

The intensity of menstrual pain is related to a woman's prostaglandin levels. Prostaglandin levels are 5 to 13 times higher in women who experience menstrual cramps than in women who do not experience menstrual cramps. The pain of menstrual cramps is similar to the pain experienced by a pregnant woman when she is given prostaglandin as a medication to induce labor.

Types of menstrual cramps/dysmenorrhea

Menstrual cramps or dysmenorrhea may be of two types, primary and secondary.

Primary dysmenorrhea

Most women, by far, suffer from the primary type of dysmenorrhea. Typically beginning at the start of menstruation (menarche), that time when a young girl begins having menstrual periods, the painful cramps of primary dysmenorrhea cannot be attributed to any gynecologic problem. The pain itself is the main problem.

Primary dysmenorrhea can be further classified into two sub-types: primary spasmodic dysmenorrhea or congestive dysmenorrhea. Primary spasmodic dysmenorrhea most commonly affects young women in their teens to late twenties and is more common in women who have never borne children. Childbearing, in fact, seems to mark the end of primary spasmodic dysmenorrhea in many women.

Primary spasmodic dysmenorrhea

Primary spasmodic dysmenorrhea is characterized by sharp, vise-like pains caused by the constriction and tightening of the uterine muscle. This pain is occasionally accompanied by sharp pains in the inner thighs and low abdominal muscles, of hot and cold, faintness to the point of passing out; nausea, vomiting, and bowel changes varying from constipation to diarrhea.

What causes this pain and cramping? The uterine muscle and the blood vessels that supply the uterus are tight and contracted. The metabolism of the uterus and pelvic muscles is decreased as a result of reduced blood circulation and oxygenation. The increase in carbon dioxide and lactic acid—waste products of metabolism Ὰ intensifies pain and discomfort.

Primary congestive dysmenorrhea

Different from the pain of spasmodic cramping, the pain that characterizes primary congestive dysmenorrhea produces a dull aching in the lower back and pelvic region—a pain often accompanied by bloating, weight gain, breast tenderness (mastalgia), headaches, and irritability. Unlike spasmodic cramping, symptoms don't improve with age and in some cases, may actually worsen. Some of the most severe symptoms are seen in women in their thirties and forties.

Are there any risk factors that contribute the pain and discomfort of primary dysmenorrhea? Yes, there are a number of risk factors that can contribute to both spasmodic and congestive menstrual cramps.

Use of tampons

Women who find that the use of tampons exacerbates their cramps should switch to sanitary napkins.

Use of an IUD

Use of an intrauterine device (IUD) can significantly worsen the spasmodic type of cramping; the IUD may need to be removed if symptoms become severe.

Bladder infections

Frequent bladder infections near or during menstrual periods can cause a dull, aching pain in the lower abdomen.

Yeast vaginitis/yeast infections

Changes in vaginal pH during menstruation can cause vaginal yeast infections during menstrual periods.

Childlessness/pregnancy

Spasmodic cramping is typically worse in women who have not borne children; congestive symptoms are typically worse in women who have had several pregnancies.

Lack of exercise/poor posture

Lack of exercise and poor posture interfere with blood circulation and oxygenation and increase the tendencies toward both types of cramps.

Stress

By causing women to tense back and pelvic muscles unconsciously, stress can worsen cramps.

Secondary Dysmenorrhea

Although sometimes evident at menarche, secondary dysmenorrhea usually develops later. Some underlying abnormal condition involving a woman's reproductive system contributes to menstrual pain.

Far less common than primary dysmenorrhea, secondary dysmenorrhea is most commonly seen among women in their forties and fifties. After years of pain-free menstruation, periods may suddenly become painful. Secondary dysmenorrhea is the result of underlying health problems such as fibroid tumors of the uterus, fibroid tumors stimulated by estrogen, pelvic inflammatory disease (PID), and endometriosis—conditions that can cause uterine and low back pain.

How are menstrual cramps diagnosed?

Diagnosis of menstrual cramps is usually made by the woman herself and is a reflection of her perception of pain. Once a woman has experienced menstrual cramps, she usually becomes familiar with their symptoms. For most women, body awareness and knowing how to maintaining optimal health allows them to manage the pain of menstrual cramps.

How are menstrual cramps treated?

Treatment of menstrual cramps should be tailored to each woman's individual needs. The most common treatment is to lie down at the first sign of pain. Although adequate rest and sleep are strongly advised, current recommendations also include regular exercise, particularly walking. Some women report a decrease in pain as a result of abdominal massage, yoga, or orgasmic sexual activity. A heating pad applied to the abdominal area can also help relieve pain and congestion.

A number of non-prescription (over-the-counter) medications can not only help control pain, but they can also help prevent cramps themselves. Medications such as Aspirin or acetaminophen (Tylenol) or acetaminophen plus a diuretic (e.g. Diurex MPR, FEM-1, Midol, Pamprin, Premsyn, and others) may be enough to alleviate mild cramps.

In the case of moderate cramps, non-steroidal anti-inflammatory drugs (NSAIDs) lower the production of prostaglandin and lessen its effect.

Table 1. NSAIDs used to treat dysmenorrhea

Non-prescription Medications	Prescription Medications
Ibuprofen (e.g. Advil, Anaprox, Midol IB, Motrin, Nuprin, and others) Naproxen (e.g. Aleve) Ketoprofen (e.g. Actron, Orudis KT)	Rofecoxib (Vioxx) mefenamic acid (Ponstel)

Such medications should be taken before pain becomes difficult to manage; this may mean starting medications 1 to 2 days before a menstrual period is due to start and continuing taking medication 1 to 2 days into a period. Routinely taking NSAIDs is more effective than waiting for the onset of pain to take them.

In the case of severe cramps, a woman may be prescribed low-dose oral contraceptives containing estrogen and progestin or long-acting edroxyprogesterone. By preventing ovulation and reducing the production of prostaglandins, these medications can reduce the severity of cramping and cause a light menstrual flow.

In the past, women who suffered severe menstrual cramps underwent a surgical procedure known as dilation and curettage (D&C) to remove some of the lining of the uterus. Other women resorted to hysterectomy, a surgery that removes the entire uterus. Today, modern techniques such as endometrial ablation allow women to retain their uterus while providing pain relief. During endometrial ablation, the lining of the uterus is burned away using a heat-generating device.

In the case of secondary dysmenorrhea, treatment depends on the cause. As we've seen, pain may be attributed to any number of underlying conditions, including endometriosis, uterine fibroids, adenomyosis, pelvic inflammatory disease, adhesions, and use of an IUD. These conditions should first be diagnosed prior to recommending appropriate treatment.

If you experience changes in your menstrual cramps, such as severity, timing, or location, consult with your doctor, particularly if these changes come on suddenly.

What's the prognosis for menstrual cramps?

Generally speaking, a woman's menstrual cramps don't worsen throughout her lifetime. The cramps of primary dysmenorrhea usually subside with age and pregnancy. In the case of secondary dysmenorrhea, where an underlying gynecologic condition contributes to pain, the prognosis depends on successful treatment of that condition.