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 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 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.
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.
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.
Hemorrhoids are swollen blood vessels that line the anal opening caused by chronic excess pressure from straining during a bowel movement, persistent diarrhea, or pregnancy. There are two types of hemorrhoids: internal and external.
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.
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.
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.
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.
Complications of diverticular disease happen in about 10 percent of people with outpouchings. They include infection or inflammation (diverticulitis), bleeding, and obstruction. Treatment of diverticulitis 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 cancer, the second most common form of cancer in the United States. Fortunately, with advances in early detection and treatment, colorectal cancer is one of the most curable forms of the disease. By using a variety of screening tests, it is possible to prevent, detect, and treat the disease long before symptoms appear.
The importance of screening
Almost all colorectal cancers begin as polyps, benign (non-cancerous) growths in the tissues lining the colon and rectum. Cancer develops when these polyps grow and abnormal cells develop and start to invade surrounding tissue. Removal of polyps can prevent the development of colorectal cancer. Almost all precancerous polyps can be removed painlessly using a flexible lighted tube called a colonoscope. If not caught in the early stages, colorectal cancer can spread throughout the body. More advanced cancer requires more complicated surgical techniques.
Most early forms of colorectal cancer do not cause symptoms, which makes screening especially important. When symptoms do occur, the cancer might already be quite advanced. Symptoms include blood on or mixed in with the stool, a change in normal bowel habits, narrowing of the stool, abdominal pain, weight loss, or constant tiredness.
Most cases of colorectal cancer are detected in one of four ways:
- By screening people at average risk for colorectal cancer beginning at age 50
- By screening people at higher risk for colorectal cancer (for example, those with a family history or a personal history of colon polyps or cancer)
- By investigating the bowel in patients with symptoms
- A chance finding at a routine check-up
Early detection is the best chance for a cure.
There are several types of colitis, conditions that cause an inflammation of the bowel. These include:
- Infectious colitis
- Ulcerative colitis (cause not known)
- Crohn's disease (cause not known)
- Ischemic colitis (caused by not enough blood going to the colon)
- Radiation colitis (after radiotherapy)
Colitis causes diarrhea, rectal bleeding, abdominal cramps, and urgency (frequent and immediate need to empty the bowels). Treatment depends on the diagnosis, which is made by colonoscopy and biopsy.