HISTORY. The Rome II criteria are used to diagnose IBS in patients who have the following symptoms for at least 3 months of the year: (1) Abdominal pain or discomfort characterized by the following: relieved by defecation, associated with a change in stool frequency, associated with a change in stool consistency; and (2) supporting symptoms including the following: altered stool frequency, altered stool form, altered stool passage, mucorrhea, abdominal bloating or subjective distension.

Symptoms that are reported most often are pain in the left lower quadrant, abdominal distention, diarrhea, and constipation, especially alternating bouts of the two. The pain may increase after eating and be relieved after a bowel movement. Pain is often cramping in nature and may be accompanied by nausea, belching, flatus, bloating, and sometimes anorexia. As the disease progresses, the patient may suffer fatigue and anxiety related to the many attempts to control the symptoms and lead a normal life. For some individuals with this disorder, the lifestyle is dictated by the need to remain close to a bathroom, which limits both occupation and social life.

PHYSICAL EXAM. With auscultation of the abdomen, normal bowel sounds may be heard, although they may be quiet during constipation. Tympanic sounds may be heard over loops of filled bowel. Although palpation often discloses a relaxed abdomen, it may reveal diffuse tenderness, which becomes worse if the sigmoid colon is palpable. The patient may have pain on rectal examination but does not usually experience rectal bleeding.

PSYCHOSOCIAL. Many patients have consulted physicians who fail to take IBS seriously, telling them to eat a high-fiber diet and relax. Unfortunately, a high-fiber diet, which is good for ordinary constipation, often makes the irritable bowel worse. As the person suffers more frequent bouts of diarrhea and constipation, any attempts to relax become futile. Anxiety over control of symptoms makes the symptoms of IBS worse, creating a vicious circle that becomes hard to break. Depression over the inability to control one's bodily functions or lead a normal life sometimes becomes a serious problem.

Diagnostic Highlights

Test	Normal Result	Abnormality with Condition	Explanation
Flexible sigmoidoscopy or colonoscopy	Visualization of normal sigmoid and colon	Intense spastic contractions; mucosa appears normal (smooth and pink)	Flexible sigmoidoscopy in adults younger than 40; colonoscopy in adults older than 40 years
Barium enema	Normal abdominal structures	Colonic spasms may occur during procedure; may have a normal examination	Identifies colonic spasms and rules out other pathology

Other Tests: Complete blood count, serological tests, serum albumin, stool for guaiac (occult blood), abdominal x-ray.