Maybe it's not IBS?

A number of gastrointestinal diseases can cause nonspecific symptoms similar to those of IBS. Fortunately, each has its own special characteristics, which should serve as red flags to patients and doctors alike (see diagram ).

Diverticular Disease. Small, finger-like sacs or pouches may protrude off the colon’s inner lining, where the blood vessels enter the colon, piercing its walls and causing areas of weakness. Unlike polyps, which are new growths within the colon lining, these pouches, known as diverticula, are actually part of the colon.

Although the condition is most common after age 50, younger people occasionally develop diverticula. Often they cause no symptoms and the individual is unaware he or she has them. When the diverticula become inflamed or infected, the condition is called diverticulitis. The symptoms of diverticulitis are much more intense than those of IBS and include severe left lower abdominal pain, chills, fever, and an elevated white blood cell count.

When diverticula become severely inflamed, the colon can become obstructed. Even worse, its wall can be perforated, resulting in peritonitis, a potentially dangerous inflammation of the membrane lining of the abdominal cavity. The diagnosis of diverticulitis is made after a number of tests, usually including a CT scan.

Treatment of diverticulitis involves a liquid diet to let the bowel rest and antibiotic therapy to clear the infection. After the immediate infection has stabilized, patients switch to a steady high-fiber diet, to help prevent flare-ups, and are advised to avoid nuts and seeds. Surgery may be required for complicated or recurrent diverticulitis.

Inflammatory Bowel Disease (IBD). Inflammatory bowel disease has a wide variety of symptoms, including persistent abdominal pain, diarrhea, rectal bleeding, fever, and weight loss. Crohn’s disease and ulcerative colitis, two conditions that together are referred to as inflammatory bowel disease, often have similar symptoms and are treated in similar ways, yet physicians regard them as distinct.

Some people experience periods of fairly good health in­­­ter­­rupted by flare-ups. Others have continuous symptoms marked by serious inflammation, intestinal bleeding, and abdominal pain. The most serious consequence of IBD is colon cancer. The risk for colon cancer is much higher for patients with IBD than for the general population.

Crohn’s disease can occur anywhere in the gastrointestinal tract, from the mouth to the anus, but it’s usually found at the end of the small intestine (ileum), in the colon, or both. It involves the full thickness of the bowel wall and may burrow into nearby organs. The bowel wall becomes thickened as well as constantly inflamed, and leakage of intestinal contents from the bowel can cause internal abscesses. A leak (fistula) that allows intestinal material to pass into the abdomen may require surgery. Severe bleeding is not a hallmark of this disease.

Crohn’s disease usually appears in young people, who develop pain in the right side of the abdomen, a low-grade fever, and perhaps changes in bowel movements. Some patients develop an abscess or fistula around the anus.

In some cases, surgery is needed to treat a complication of the disease, such as bowel obstruction. About 40%–60% of those with Crohn’s eventually need surgery to remove damaged areas of their small intestine or colon.

Ulcerative colitis is characterized by inflammation of the lining, or mucosa, of the colon. Like IBS, it can cause lower abdominal pain and diarrhea. Unlike IBS, the stool generally contains blood, and bowel symptoms may be accompanied by fever, weight loss, an elevated white blood cell count, and the same non-gut manifestations as Crohn’s disease. Ulcerative colitis is easier to diagnose than Crohn’s disease and is treated with many of the same medications; it can even be cured because it affects only the colon, which can be surgically removed.
Surgery is too drastic a treatment in most cases, but about 25% of patients eventually have surgery to remove their colons.

While drugs cannot cure IBD, they are effective in reducing inflammation and accompanying symptoms in about 80% of patients. The drugs used most commonly are aminosalicylates (cousins of aspirin), steroids (potent anti-inflammatory agents), immunosuppressants like azathioprine (Imuran), and antibiotics. Another drug, infliximab (Remicade), has proved effective for patients with Crohn’s disease.

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