Digestive Bowel Disorders

(USMLE topics) IBS versus IBD: differences in symptoms, pathophysiology, epidemiology. This video is available for instant download licensing here:
Voice by: Ashley Fleming
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Despite sharing some similar symptoms, inflammatory bowel disease, IBD, and irritable bowel syndrome, IBS, are two very different disorders of the digestive system.
IBD, which includes ulcerative colitis and Crohn’s disease, results from an inappropriate response of the immune system. The bowel in IBD is inflamed, causing damage that can readily be seen with imaging techniques such as colonoscopy. IBD may have serious complications and may increase risks for colon cancers.
IBS, on the other hand, is a functional disorder, meaning the bowel does not function properly, but there is no visible structural damage. It rarely requires hospitalization and does not increase risks for colon cancer.
IBS is thought to associate with problems in the gut-brain axis, a system by which the nervous system regulates gut activities, such as intestinal muscle contraction and digestive enzyme secretion. The system ensures that the colon moves food at an optimal pace, allowing the body to reabsorb the right amount of water and nutrients before stools can form. IBS patients often have irregular colon motility patterns. When food moves too fast through the colon, less water is reabsorbed and stools become more watery. When food moves too slowly, more water is reabsorbed and constipation results. Sensory nerve endings in the bowel of IBS patients are also more sensitive, or “irritated”, producing the sensation of pain.
Typical IBS symptoms include abdominal pain or discomfort that is often relieved upon defecation, mucus in stools, bloating, gassiness, and diarrhea or constipation, sometimes alternating bouts of diarrhea and constipation. Symptoms of IBS do not include anemia, intestinal bleeding, weight loss, or fever. People with IBS are more likely to have other functional disorders such as fibromyalgia or chronic fatigue syndrome; while IBD patients often experience inflammation of joints, skin and eyes. IBS symptoms can be triggered by stress, certain foods, and often get worse around menstrual periods in women. IBD is not known to associate with any obvious triggers.
IBS is much more common than IBD. The 2 disorders affect similar age groups, but IBS affects more women than men.
Treatments for IBD include a number of medications, and often surgeries, while most cases of IBS can be managed with diet, and stress reduction.