Functional disorders
Functional disorders are those in which the bowel looks normal but doesn’t work properly. They are the most common problems affecting the colon and rectum, and include constipation and irritable bowel syndrome (IBS). The primary causes for functional disorders include:

• Eating a diet low in fiber
• Not drinking enough water or other fluids
• Not getting enough exercise
• Traveling or other changes in routine
• Eating large amounts of dairy products
• Being stressed
• Resisting the urge to have a bowel movement
• Resisting the urge to have bowel movements due to pain from hemorrhoids
• Overusing laxatives (stool softeners) that, over time, weaken the bowel muscles
• Taking antacid medicines containing calcium or aluminum
• Taking certain medicines (especially antidepressants, iron pills, and strong pain medicines such as narcotics)
• Being pregnant

Constipation
Constipation is the difficult passage of stools (bowel movements) or the infrequent (less than three times a week) or incomplete passage of stools. Constipation is usually caused by inadequate “roughage” or fiber in the diet, or a disruption of the regular routine or diet. Constipation causes a person to strain during a bowel movement. It might include small, hard stools, and sometimes causes anal problems such as fissures and hemorrhoids. Constipation is rarely the sign of a more serious medical condition.

Treatment of constipation includes increasing the amount of fiber you eat, drinking more fluids, exercising regularly, and moving your bowels when you have the urge (resisting the urge causes constipation). If these treatment methods don’t work, laxatives are a temporary solution. Note that the overuse of laxatives can actually aggravate symptoms of constipation. Always follow the package instructions on the laxative medicine, as well as the advice of your doctor.

Irritable bowel syndrome (IBS)
Irritable bowel syndrome (also called spastic colon, irritable colon, or nervous stomach) is a condition in which the colon muscle contracts more readily than in people without IBS. A number of factors can trigger IBS including certain foods, medicines, and emotional stress. Symptoms of IBS include abdominal pain and cramps, excess gas, bloating, and a change in bowel habits such as harder, looser, or more urgent stools than normal. Often people with IBS have alternating constipation and diarrhea.

Treatment includes avoiding caffeine, increasing fiber in the diet, drinking more fluids, monitoring which foods trigger IBS (and avoiding these foods), quitting smoking, minimizing stress or learning different ways to cope with stress, and sometimes taking medicines as prescribed by your health care provider.

Structural disorders
Structural disorders are those in which the bowel looks abnormal and doesn’t work properly. Sometimes, the structural abnormality needs to be removed surgically. The most common structural disorders are those affecting the anus, as well as diverticular disease and cancer.

Anal disorders

Hemorrhoids are swollen blood vessels that line the anal opening caused by excess pressure from straining during a bowel movement, persistent diarrhea, or pregnancy. There are two types of hemorrhoids: internal and external.

• Internal hemorrhoids — Internal hemorrhoids are normal structures cushioning the lower rectum and protecting it from damage by stool. When they fall down into the anus as a result of straining, they become irritated and start to bleed. Ultimately, internal hemorrhoids can fall down enough to prolapse (sink or protrude) out of the anus.Treatment includes improving bowel habits (such as avoiding constipation, not straining during bowel movements, and moving your bowels when you have the urge), using elastic bands to pull the internal hemorrhoids back into the rectum, or removing them surgically. Surgery is needed only for a small number patients with very large, painful, and persistent hemorrhoids.
• External hemorrhoids — External hemorrhoids are veins that lie just under the skin on the outside of the anus. Sometimes, after straining, the external hemorrhoidal veins burst and a blood clot forms under the skin. This very painful condition is called a pile.Treatment includes removing the clot and vein under local anesthesia in the doctor’s office.

Anal fissures are splits or cracks in the lining of the anal opening. The most common cause of an anal fissure is the passage of very hard or watery stools. The crack in the anal lining exposes the underlying muscles that control the passage of stool through the anus and out of the body. An anal fissure is one of the most painful problems because the exposed muscles become irritated from exposure to stool or air, and leads to intense burning pain, bleeding, or spasm after bowel movements.

Initial treatment for anal fissures includes pain medicine, dietary fiber to reduce the occurrence of large, bulky stools, and sitz baths (sitting in a few inches of warm water). If these treatments don’t relieve pain, surgery might be needed to decrease spasm in the sphincter muscle.

Perianal abscesses can occur when the tiny anal glands that open on the inside of the anus become blocked, and the bacteria always present in these glands cause an infection. When pus develops, an abscess forms. Treatment includes draining the abscess, usually under local anesthesia in the doctor’s office.

An anal fistula often follows drainage of an abscess and is an abnormal tube-like passageway from the anal canal to a hole in the skin near the opening of the anus. Body wastes traveling through the anal canal are diverted through this tiny channel and out through the skin, causing itching and irritation. Fistulas also cause drainage, pain, and bleeding. They rarely heal by themselves and usually need surgery to drain the abscess and “close off” the fistula.

Other perianal infections
Sometimes the skin glands near the anus become infected and need to be drained. Just behind the anus, abscesses can form that contain a small tuft of hair at the back of the pelvis (called a pilonidal cyst).

Sexually transmitted diseases that can affect the anus include anal warts, herpes, AIDS, chlamydia, and gonorrhea.

Diverticular disease
Diverticulosis is the presence of small outpouchings (diverticula) in the muscular wall of the large intestine that form in weakened areas of the bowel. They usually occur in the sigmoid colon, the high-pressure area of the lower large intestine.

Diverticular disease is very common and occurs in 10 percent of people over age 40 and in 50 percent of people over age 60 in Western cultures. It is often caused by too little roughage (fiber) in the diet. Diverticulosis rarely causes symptoms but when the occur, they might include tenderness over the affected area or muscle spasms in the abdomen.

Complications of diverticular disease happen in about 10 percent of people with outpouchings. They include infection or inflammation (diverticulitis), bleeding, and obstruction. Treatment includes antibiotics, increased fluids, and a special diet. Surgery is needed in about half the patients who have complications to remove the involved segment of the colon.

Colon polyps and cancer
Each year 130,000 Americans are diagnosed with colorectal cance

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