Ch 13: Small Intestine Flashcards
Persistence of vitelline duct, outpouching of all three layers of the bowel wall. Can be complicated by bleeding or inflammation.
Meckel diverticulum
Note: since all three layers go through, this is a “true” diverticulum
On the spectrum of bacterial diarrhea, which organisms are typical for causing toxigenic diarrhea and which are invasive?
Toxigenic: Vibrio cholerae, toxigenic E. coli
Invasive: Shigella, Salmonella, E. coli, Yersinia, Campylobacter
What are the most common causes of viral gastroenteritis in the U.S.?
Rotavirus, norwalk virus
You suspect a small bowel infarction in a patient. What features of the infarct will help you determine the cause?
Transmural infarct: occurs from thrombus/embolism of SMA (A. fib or vasculitis) or thrombosis of mesenteric vein (Lupus anticoagulant or polycythemia vera)
Mucosal infarct: hypotension (shock etc)
There are two types of malabsorption in the small bowel: 1) luminal phase (involving physiochemical state of nutrients) and 2) intestinal phase (processes in cells and transport channels). Describe the different ways that these malabsorption patterns can arise.
Luminal: interruption of distal stomach and duodenum, pancreatic dysfunction, or deficient/ineffective bile salts
Intestinal: microvilli abnormality, diminution of absorptive area, decreased metabolic function of absorptive cells, impaired transport
Child presents with abdominal pain, diarrhea, and failure to thrive. After 3 months on a gluten free diet, their symptoms have disappeared. What findings would have been present on their initial presentation?
This is celiac disease, an immune mediated damage of small bowel due to gluten exposure and CD8 T lymphocytes - associated with HLA-B8/DQ2/DR8
Lab: IgA Abs against endomysium, tissue transglutaminase, or gliadin (IgG Abs if patient is IgA deficient)
Biopsy: flattening of villi, hyperplasia of crypts, increased intraepithelial lymphocytes, mostly in duodenum
Patient with history of celiac disease presents with lots of small vesicles on their skin. He admits to not always adhering to a gluten free diet. What are the skin lesions and what are they due to?
Dermatitis herpetiformis, due to IgA deposition at tips of dermal papillae which cause skin to blister
Cause of fat malabsorption and steatorrhea due to compression of lacteals in lamina propria by macrophages
Whipple disease
Macrophages are loaded with Tropheryma whippelii and will stain for PAS
Inability to assemble chylomicrons and transport fat. Causes acanthocytosis and selective demyelination.
Abetalipoproteinemia - autosomal recessive deficiency of apolipoprotein B48 and B100
What are the difference between celiac disease and tropical sprue?
Tropical sprue is due to damage from unknown organism, is mostly seen in the jejunum and ileum (as opposed to duodenum in celiac), results in B12 or folate deficiency, occurs in tropical regions, and responds to antibiotics
Infant presents seeming generally pissed off, and when you complete your full physical you notice that they are more irritable when you poke their abdomen. You check the diaper and see currant jelly stools. After you promptly vomit, what diagnosis do you make?
Intussusception, when a portion of the small bowel telescopes into a distal segment
Can result in obstruction and disruption of blood supply to this segment of bowel - medical emergency!
In children, caused by lymphoid hyperplasia. In adults, caused by tumor.
An 11 yo girl presents at your office with patchy dark spots on her oral mucosa, face, and hands. You throwback to Rubin’s Unit 6 and diagnose Peutz-Jeghers Syndrome. What GI manifestations are seen with this disease?
Intestinal hamartomatous polyps, with an increased risk of obstruction and intussusception
Associated with inactivating mutations of LKB1
What clinical manifestations will you see with a carcinoid tumor of the small bowel that hasn’t yet metastasized?
Secretes serotonin, which travels to portal circulation and is metabolized by liver MAO to 5-HIAA, which is excreted and can be measured in urine
If a carcinoid tumor metastasizes to bypass the liver, what clinical manifestations will be seen?
Serotonin bypasses metabolism, so will see bronchospasm, diarrhea, flushing of skin (made worse by alcohol or emotional stress)
Can also lead to right sided heart fibrosis with tricuspid regurgitation and pulmonary valve stenosis
