Constipation

(Hard Stools, Difficulty Passing Stool)

In this factsheet:

• The Facts on Constipation
• Causes of Constipation
• Symptoms and Complications of Constipation
• Diagnosing Constipation
• Treating and Preventing Constipation

The Facts on Constipation

Constipation occurs when stool or waste material moves too slowly through the large intestine. Feces that stay in the bowel too long before elimination become hard and dry. This results in difficult, painful, and infrequent bowel movements. In most cases, constipation is harmless. It's not a disease, but it might be a symptom of a disease.

Many elderly people believe they are constipated when they're not, thinking that less than one bowel movement a day is abnormal. In fact, as little as twice a week is fine so long as you go when you feel the need. In contrast, infants may go anywhere from 5 times daily to every fifth day!

Causes of Constipation

When food leaves the stomach, it's still a partly digested mush. Your body recuperates valuable fluid from it while it's moved down the colon (large intestine). This transforms it into normal feces. The longer it stays in the colon, the drier it gets. That makes it harder.

Obviously, the quantity also increases if you wait to go to the toilet. A large, hard stool can be painful and difficult to pass. This can make people, especially children, reluctant to go, creating a vicious cycle. It's the common pattern of chronic constipation in children. It often begins when they start school. Many young children avoid the school toilets and end up waiting too long.

Chronic constipation can last for months or years. It's usually caused by poor diet, by some other disease, or by regularly ignoring the urge to go to the toilet. Low-fibre diets and insufficient water intake are the leading causes of constipation.

While most otherwise healthy people will occasionally experience constipation, certain diseases or conditions can also cause it:

• bowel obstructions, such as a tumour or benign growth
• chronic kidney failure
• hypothyroidism
• irritable bowel syndrome
• neurogenic disorders such as Parkinson's disease, multiple sclerosis, or spinal cord injury
• rectal or colon cancer

Acute constipation starts suddenly and lasts a few days. It can be caused by a blockage, prolonged inactivity, medication, dehydration, or missing a bowel movement. Pregnant women can develop constipation when the womb presses on the intestine. Sometimes, general anesthetic affects the bowel muscles for a few days after surgery. Lead poisoning and swallowing indigestible objects are other occasional causes.

All of the following medications can slow the passage of feces through the intestine, provoking acute constipation:

• anticonvulsants used for epilepsy
• antidepressants
• diuretics
• heart medications such as calcium-channel blockers
• iron supplements
• pain medications such as codeine and morphine
• some cough and cold medications containing dextromethorphan
• some antacids

Overuse of laxatives eventually makes the bowels less sensitive to the need to eliminate feces and can cause chronic constipation. The bowels become dependent on laxatives to work, and this can lead to bowel distension and a condition called melanosis coli.

People who are bedridden can develop severe acute blockages called fecal impaction. These may have to be removed by your doctor.

Symptoms and Complications of Constipation

Symptoms of constipation can include:

• a sensation that the bowels haven't completely emptied
• bloating of the abdomen, and possibly a "rumbling" noise
• gas
• indigestion
• infrequent bowel movements
• hard, dry stools that are difficult to pass
• loss of appetite
• pain or pressure in the belly
• some bleeding as a result of straining

Constipation can cause complications. Very large, hard stools can stretch the anus, tearing the skin. These anal fissures can be very painful. Occasionally, a really tough bowel movement causes rectal prolapse, in which a small section of intestinal lining pokes out of the anus and has to be pushed back in.

Chronic constipation increases the risk of diverticulitis. This is when small pockets called diverticula are formed by the chronic increased pressure inside the bowel wall muscle and eventually get blocked and infected. Hemorrhoids can also be caused by the chronic pushing of constipation.