Menstrual cramps are among the symptoms that most often accompany menstruation. They are a type of pelvic pain characterized by sharp cramping or a dull aching sensation in the lower abdomen. Many women experience these symptoms just before and during their menstrual periods. The medical term for menstrual cramps is dysmenorrhea. However, physicians most often use the term when describing severe menstrual pain that interferes with daily life or that may require medical treatment for an underlying disorder.

To create a nourishing environment for a fertilized egg, the female sex hormone estrogen causes the uterine lining (endometrium) to thicken every month. Soon after, a follicle – a tiny sac in the ovary that contains a single egg (ovum) – ruptures and releases the egg during a process called ovulation. If the egg becomes fertilized by sperm on its way to the uterus, the egg implants in the lining of the uterus. However, if fertilization does not occur, the egg passes through the uterus and out of the body. Shortly thereafter, the uterus releases the lining and the menstrual flow begins.

To help expel its lining, the uterus contracts. These menstrual contractions or cramps can often be painful. For some, the pain or discomfort is minimal. For others, it can be very severe and interfere with everyday activities for a few days every month.

There are two types of menstrual cramps:

• Primary dysmenorrhea. Lower abdominal pain that occurs during a woman’s menses and is not associated with any type of physical abnormality or disease. It usually begins within three years of the onset of menstruation (menarche).
  
  In this type of dysmenorrhea, the pain characteristically begins at the start of menstruation and gradually diminishes over two to three days. Usually, the pain is strongest in the abdomen, although some women experience pain in their back or thighs.
  
  
• Secondary dysmenorrhea. The occurrence of painful menstruation accompanying an underlying health condition such as endometriosis, uterine fibroids or pelvic inflammatory disease (PID).
  
  Women with secondary dysmenorrhea often have symptoms and physical findings that alert the physician to the presence of an underlying pelvic disease. For example, women with severe menstrual cramps due to endometriosis often experience pain that begins mid-cycle and becomes progressively more severe the week before menstruation. It is sometimes accompanied by constipation.

Menstrual cramps are very common and often are not a cause of concern. However, if a woman experiences dysmenorrhea that interferes with daily life for several days a month, or if she is older and is just starting to experience severe menstrual cramps, it is important that she contact a physician, preferably a gynecologist, for an examination. 

If left untreated, some of the pelvic conditions associated with secondary dysmenorrhea (e.g., endometriosis, PID) can chronically interfere with daily activities and compromise a woman’s reproductive health, possibly resulting in infertility. Identifying the underlying cause of dysmenorrhea is the first step for successful treatment.