Chapter 45
Inflammatory Bowel Disease and IBS
Two inflammatory diseases plus a functional one
IBD and IBS: The Big Picture
Inflammatory bowel disease (IBD) describes two idiopathic diseases: ulcerative colitis (UC), chronic mucosal inflammation of the rectum and colon, and Crohn disease (CD), chronic transmural inflammation anywhere from mouth to anus (most often small bowel and colon). Irritable bowel syndrome (IBS) is a functional disorder of GI motility with abdominal pain and altered bowel habits and NO structural cause.
The critical distinction: IBD is a structural, inflammatory disease; IBS is functional. IBS lacks 'alarm signs' (weight loss, anemia, bloody stools, onset over 50, family history of cancer/IBD/celiac) -- any alarm sign points away from IBS toward IBD or cancer.
UC vs CD One-Liner
UC = continuous MUCOSAL inflammation limited to the colon/rectum. CD = patchy 'skip lesions' with TRANSMURAL inflammation anywhere in the GI tract. Surgery cures UC but NOT CD (which recurs).
📖 “IBD = UC (mucosal, rectum/colon, continuous) + CD (transmural, mouth to anus, skip lesions). IBS = functional motility disorder, no structural cause, abdominal pain + altered bowel habits; alarm signs (weight loss, anemia, bloody stool, onset >50, family history) argue against IBS.”