Most patients have pain over at least one area of the colon, associated with periodic constipation alternating with a more normal stool frequency. Stool often contains clear or white mucus. Eating commonly triggers symptoms. Bloating, flatulence, nausea, dyspepsia, and pyrosis can also occur. Diarrhea-predominant IBS is characterized by precipitous diarrhea that occurs immediately on rising or during or immediately after eating.
Nocturnal diarrhea is unusual.
Pain, bloating, and rectal urgency are common, and incontinence may occur. Diagnosis Diagnosis of IBS is based on characteristic bowel patterns, time and character of pain, and exclusion of other disease processes through physical examination and routine diagnostic tests. The Rome criteria for IBS includes abdominal pain relieved with defecation and a varying pattern of altered stool frequency or form, bloating, or mucus. The key to diagnosis is effective history taking, which requires attention to directed, but not controlled, elaboration of the presenting symptoms, history of present illness, past medical history, family history, familial interrelationships, and drug and dietary histories. Equally important are the patient's interpretation of personal problems and overall emotional state.