True about irritable bowel syndrome –
**Core Concept**
Irritable bowel syndrome (IBS) is a functional gastrointestinal disorder characterized by chronic abdominal pain, bloating, and changes in bowel habits in the absence of any visible structural abnormalities. The pathophysiology of IBS is complex, involving alterations in gut motility, sensitivity, and the gut-brain axis.
**Why the Correct Answer is Right**
The exact mechanisms underlying IBS are not fully understood, but several factors contribute to its development, including:
* Abnormal gut motility and hypersensitivity to distension
* Alterations in gut hormones, such as serotonin and motilin
* Changes in the gut microbiome and inflammation
* Stress and anxiety-induced modulation of the gut-brain axis
**Why Each Wrong Option is Incorrect**
**Option A:** IBS is primarily caused by a bacterial overgrowth of small intestine.
* This is incorrect because while gut dysbiosis may play a role, it is not the primary cause of IBS.
**Option B:** IBS is typically diagnosed by endoscopy and colonoscopy.
* This is incorrect because IBS is diagnosed based on clinical criteria and exclusion of other organic causes, not by invasive diagnostic procedures.
**Option C:** IBS is a type of inflammatory bowel disease (IBD).
* This is incorrect because IBS and IBD are distinct conditions, with IBS characterized by the absence of inflammation and IBD marked by chronic inflammation and damage to the gastrointestinal tract.
**Clinical Pearl / High-Yield Fact**
A key aspect of IBS is its classification into different subtypes based on bowel habits, including IBS-D (diarrhea-predominant), IBS-C (constipation-predominant), and IBS-M (mixed).
**Correct Answer:** C. IBS is a type of functional gastrointestinal disorder, not inflammatory bowel disease.