Small Bowel Flashcards
What is the most common cause of small bowel obstruction?
Adhesions (post-surgical or inflammatory).
What is Meckel’s diverticulum?
A true diverticulum due to failure of the vitelline duct to involute.
What is the rule of 2’s in Meckel’s diverticulum?
2% of population, 2 inches long, 2 feet from ileocecal valve, 2 types of epithelia (gastric and pancreatic), presents in first 2 years.
What is volvulus?
Twisting of the bowel along its mesentery, leading to obstruction and infarction.
Where does volvulus commonly occur in elderly and young adults?
Sigmoid colon in elderly, midgut in young adults.
What is intussusception?
Telescoping of proximal segment into a distal segment due to peristalsis.
What is the most common cause of intussusception in children?
Lymphoid hyperplasia (due to rotavirus infection).
What is the most common cause of intussusception in adults?
Tumors.
What is the primary mechanism of ischemic bowel disease?
Decreased blood flow due to thrombosis, embolism, or hypoperfusion.
What area of the small intestine is most susceptible to ischemia?
The watershed areas, such as the splenic flexure.
What are the types of infarction in ischemic bowel disease?
Mucosal, mural, and transmural infarction.
What is Celiac disease?
Immune-mediated damage to small bowel due to gluten exposure in genetically predisposed individuals.
What is the pathophysiology of Celiac disease?
Gliadin is deamidated by tissue transglutaminase (tTG), presented by MHC class II to T cells, triggering an immune response.
What are the serologic markers for Celiac disease?
IgA anti-tTG, IgA anti-endomysial, IgA anti-gliadin antibodies.
What histologic features are seen in Celiac disease?
Villous atrophy, crypt hyperplasia, increased intraepithelial lymphocytes.
What malignancy is associated with Celiac disease?
Enteropathy-associated T-cell lymphoma (EATL).
What is Tropical sprue?
A malabsorption disorder similar to Celiac disease but occurring in tropical regions due to bacterial overgrowth.
What deficiency is common in Tropical sprue?
Folate and B12 deficiency due to jejunal and ileal involvement.
What is Whipple disease?
Infection with Tropheryma whipplei leading to PAS-positive macrophages in the lamina propria.
What are the clinical features of Whipple disease?
Malabsorption, arthritis, cardiac symptoms, and CNS involvement.
What is Abetalipoproteinemia?
Autosomal recessive deficiency of ApoB-48 and ApoB-100 leading to fat malabsorption.
What is the most common type of small bowel tumor?
Carcinoid tumor.
What hormone is secreted by carcinoid tumors?
Serotonin.
What is carcinoid syndrome?
Flushing, diarrhea, bronchospasm, right-sided heart fibrosis due to serotonin excess (only when metastasized to liver).
