Irritable Bowel Syndrome II: Clinical Features and Diagnostic Evaluation

Irritable Bowel Syndrome (IBS) is classified into subtypes based on the predominant bowel habits as determined by the Bristol Stool Form Scale (BSFS). The subtypes are:

1. IBS-C is primarily characterized by constipation. Individuals may experience infrequent bowel movements, difficulty passing stools, or a sensation of incomplete evacuation.
2. IBS-D, which involves recurrent episodes of diarrhea, is marked by an urgency to pass stools and frequent trips to the bathroom.
3. IBS-M, or mixed-type IBS, features a combination of both constipation and diarrhea with alternating bowel habits.
4. IBS-U (Unclassified) is for individuals whose symptoms do not conform to the above subtypes, including those with inconsistent or changing symptoms that do not follow a specific pattern.

Associated symptoms include abdominal distention, bloating, nausea, flatulence, an urgency to have a bowel movement, mucus in the stool, and a persistent sensation of incomplete evacuation. Notably, abdominal bloating often leads to visible distention. Besides gastrointestinal symptoms, non-gastrointestinal manifestations such as fatigue, headaches, and sleep disturbances may occur.

The diagnosis of IBS follows the Rome symptom-based criteria, which require the presence of abdominal pain or discomfort at least once a day over the last three months. The pain should be associated with two or more of the following:

1. Abdominal pain related to defecation
2. Abdominal pain accompanied by changes in stool frequency
3. Abdominal pain accompanied by changes in stool form or appearance

This systematic approach helps identify specific patterns of symptoms indicative of IBS.

To rule out other gastrointestinal conditions and confirm an IBS diagnosis, various diagnostic tests may be recommended, including:

1. Blood investigations to check for signs of inflammation or other underlying conditions.
2. Stool studies to analyze stool composition and rule out infections or malabsorption issues.
3. X-rays and abdominal scans to provide detailed images of the gastrointestinal tract and surrounding structures.
4. Colonoscopy, a medical procedure that involves inserting a camera-equipped flexible tube into the colon to visualize its internal structure and identify the root cause of symptoms.