Constipation is a decrease in the frequency of bowel movements or difficulty in the formation of, or passing of, stool (the body's solid waste).
Constipation occurs in the colon, also known as the large intestine. This part of the digestive tract controls the formation and passage of stool from the body. The colon absorbs water out of the solid waste and uses muscles to move the waste along toward the rectum and anus for passage out of the body.
If too much water is absorbed from the waste as it passes through the colon, hard and dry stools that are difficult to excrete can result. Another cause of constipation may be changes in the muscle contractions of the colon that cause waste to become "stuck." Things that block the colon, such as a tumor or swelling due to infection, also may cause constipation. In cases of cancer patients, the number one cause of constipation is the use of certain medications for treatment.
Since constipation relates to how often a person has bowel movements, which differs depending on the individual, what can be considered constipation for one person may be normal for another.
For example, if it is normal for a person to have three bowel movements per day, and he is having only one per day, this may signal constipation. On the other hand, another person's typical bowel pattern may be to have a bowel movement every other day. In this case, constipation might be defined as only having a bowel movement two to three times per week.
