Flashcards in Small Bowel and Colon DSA Deck (57):
Noninfl diarrhea- viral, protozoal, bacterial enterotoxin production
-Giardia, Cryptosporidium, Cyclospora
-preformed enterotoxin- Staph aureus, Bacillus cereus, Clostridium perfringens
-Enterotoxin production- ETEC, Vibrio cholera
Infl diarrhea- viral, protozoal, cytotoxin production, mucosal invasion
-Cytotoxin production- EHEC, Vibrio parahaemylyticus, C difficile
-Mucosal invasion- shigella, campylobacter, salmonella, EIEC, others
Initial diagnostic tests
-CBC, serum electrolytes, liver fxn tests, ca, phosphorus, TSH, vit A and D levels, INR, ESR, CRP
-tTG test- celiac dz
-stool studies- ova, parasites, fat, occult blood, leukocytes or lactoferrin
-colonoscopy and mucosal biopsy- exclude CD, microscopic colitis, colonic neoplasia
chronic diarrhea- exclude? tests?
-causes of acute diarrhea
-previous gastric surgery or ileal resection
*fecal leukocytes and occult blood; colonoscopy with biopsy; small bowel imaging with barium, CT, or MR enterography
chronic diarrhea- Lab tests
-serologic tests for neuroendocrine tumors
-breath test- dx small bowel bacterial overgrowth
Pernicious Anemia Gastritis
-rare autosomal disorder- fundic glands
-achlorhydria, dec IF secretion, vit B12 malab
-severe gland atrophy and intestinal metaplasia
-autoimmune destruction of gastric fundic mucosa
-achlorhydria leads to hypergastrinemia!!- 5% of pts develop carcinoid tumors
weight loss, m wasting- malabsorption of?
fat, protein, carbs
microcytic anemia- malabsorption of?
macrocytic anemia- malabsorption of?
vit B12 or folic acid
paresthesia, tetany, Trousseau and Chvostek signs- malabsorption of?
-Calcium, Vit D, magnesium
bone pain, fractures, skeletal deformities- malabsorption of?
calcium, vit D
bleeding tendency (ecchymoses, epistaxis)- malabsorption of?
-Vit K (prolonged PT or INR)
Milk intolerance (cramps, bloating, diarrhea)- malabsorption of?
edema- malabsorption of?
Celiac Dz- essentials of diagnosis
-typical sx- weight loss, chronic diarrhea, abd distension, growth retardation
-atypical sx- dermatitis herpetiformis, iron def anemia, osteoporosis
-abnormal serologic test results
-abnormal small bowel biopsy
-clinical improvement on gluten-free diet
Celiac dz- in who?
Celiac dz- lab testing
-IgA tTG ab!!
-confirmation- mucosal biopsy- intraepit lymphocytes
Celiac dz- treatment
-removal of gluten from diet
-dietary supplements (short-term)
Whipple Disease- essentials of diagnosis
-fever, lymphadenopathy, arthralgias
-weight loss! (most common sx), malabs, chronic diarrhea
-duodenal biopsy with PAS-positive macrophages with characteristic bacillus
Whipple disease- caused by? in who?
-Tropheryma whipplei (bacillus)
-white men; 40-60's
Whipple disease- dx
-endoscopic biopsy of duodenum- shows infiltration of lamina propria with PAS-positive macrophages that contain gram-positive bacilli
Short Bowel Syndrome- causes
-malabsorptive condition- due to removal of segments of the small intestine
-causes- CD, mesenteric infarction, radiation enteritis, volvulus, tumor resection, trauma
-malabs depends on length and site of resection
terminal ileal resection
-malabs of bile salts and vit B12
-no bile salts- steatorrhea and malabs of fat-soluble vitamins
extensive small bowel resection
-weight loss and diarrhea due to nutrient, water, and electrolyte malabsorption
-if have less than 100-200 cm of proximal jejunum- require parenteral nutrition
Lactase Deficiency- essentials of diagnosis
-diarrhea, bloating, flatulence, abd pain after ingestion of milk-containing products
-dx supported by symptomatic improvement on lactose-free diet
-dx confirmed by hydrogen breath test
Lactase Deficiency- in who?
-90% asian ams, 70% Af ams, 95% native ams, 50% mexican ams, 60% jewish ams, <25% of white adults
Lactase Deficiency- lab findings
-hydrogen breath test!
Irritable Bowel Syndrome- essentials of diagnosis
-chronic fxnal disorder characterized by abd pain or discomfort with alterations in bowel habits
-sx usually begin in late teens to early 20's
-limited evaluation to exclude organic causes of sx's
Irritable Bowel Syndrome- defined as?
-sx's not explicable by the presence of structural or biochemical abnormalities!!
-chronic (>6 months) abd pain/discomfort and altered bowel habits
-relieved with defecation, onset assoc with a change in freq of stool, or onset assoc with a change in form of stool (2 out of the 3!)
Irritable bowel syndrome- pathogenesis
-psychosocial abnormalities (50% have depression, anxiety, or somatization)
Irritable bowel syndrome- treatment
-reassurance, education, support
-explain mind-gut interaction- visceral motility and sensitivity changes can be exacerbated by environmental, social, or psyhological factors
-most common- inadequate fiber/fluid intake, poor bowel habits
-systemic dz- endocrine, metabolic, neurologic
-slow colonic transit
-pelvic floor dyssynergia
Fecal Impaction- predisposing factors, presentation
-fecal impaction in rectal vault- can lead to large bowel obstruction
-predisposing factors- medications (opioids), psychiatric dz, prolonged bed rest, neurogenic disorders of colon, spinal cord disorders
-dec appetite, N/V, abd pain and distension
-tx- enemas or digital disruption of the impacted fecal material
Antibiotic-Associated Colitis- essentials of diagnosis
-most cases of abx-assoc diarrhea are not due to C difficile and are usually mild and self-limited
-sx- vary from mild to fulminant- almost all colitis is due to C difficile
-dx- stool assay
Antibiotic-Associated Colitis- caused by
C difficile- TcdA and TcdB (toxins)
-major cause of diarrhea in pts who have been hospitalized for >3 days
-transmitted from pt to pt by hospital personnel
Antibiotic-Associated Colitis- virulent strain
-NAP1- higher toxin A and B production
Antibiotic-Associated Colitis- sx
-mild-moderate greenish, foul-smelling watery diarrhea
-severe/fulminant dz occurs in 10%- fever, hemodynamic instability, abd distension and pain
Antibiotic-Associated Colitis- exam
-EIAs for toxins TcdA and TcdB
-PCR assay- more sensitive
-flexible sigmoidoscopy (doesnt need to be done if pts have a positive stool toxin assay)- pseudomembranes
-lymphocytic and collagenous types
-mucosal biopsies- chronic infl in lamina propria, inc intraepit lymphocytes
-collagenous colitis- thickened band of subepit collagen
-women- 5-6 decades
Diverticular Disease of the Colon
-90% of pts with diverticulosis have uncomplicated dz and no sx!!
-usually an incidental finding
-tx- high-fiber diet
Diverticulitis- essentials of diagnosis
-acute abd pain and fever
-left lower abd tenderness and mas
-empiric medical therapy first!
-colonoscopy or CT or barium enema- to exclude colonic neoplasms
-diverticulosis causes 1/2 of all cases of acute lower GI bleeding!
polyps of the colon
-mucosal adenomatous polyps
-mucosal serrated polyps (hyperplastic, sessile serated)
-mucosal nonneoplastic polyps (juvenile, hamartomas, infl)
*70% are adenomatous
Nonfamilial adenomatous and serrated polyps
-in 30% of adults > 50 yo
-95% of adenocarcinomas arise from these lesions!
-inact of APC gene
-adenoma > 1cm, dysplasia- advanced!
Nonfamilial adenomatous and serrated polyps- fecal occult blood or multitarget DNA tests
-FOBT, FIT, fecal DNA tests- screening
-Cologuard- fecal DNA test with test for stool hemoglobin
Nonfamilial adenomatous and serrated polyps - radiologic tests
-polyps IDed by barium enema exams or CT colonography
Nonfamilial adenomatous and serrated polyps- endoscopic tests
-colonoscopy- best way of detecting and removing adenomatous and serrated polyps
-done in all pts who have positive FOBT, FIT, fecal, or DNA tests
Familial Adenomatous Polyposis- essentials of diagnosis
-inherited condition- characterized by early development of 100-1000s of colonic adenomatous polyps and adenocarcinoma
-extracolonic manifestations- duodenal adenomas, desmoid tumors, osteomas
-attenuated variant with <500 colonic adenomas
-genetic testing- mutation of APC (90%) or MUTYH (8%)
-prophylactic colectomy- recommended to prevent colon cancer
-colorectal polyps at age 15; cancer at 40 yo
-colorectal cancer inevitable by age 50- unless prophylactic colectomy
-extraintestinal manifestations- hypertrophy of retinal pigment, desmoid tumors, osteomas
FAP- genetic testing
-complete proctocolectomy with ileoanal anastomosis or colectomy with ileorectal anastomosis!!- b/f age 20!
Hamartomatous Polyposis Syndromes
-Peutz-Jeghers syndrome (AD- polyps, mucocutaneous pigment, 40% chance of malignancy)
-Familial juvenile polyposis (AD- several polyps in colon, 50% risk of adenocarcinoma)
Lynch syndrome (HNPCC)- essentials of diagnosis
-mutations in gene that detects/repairs DNA base-pair mismatches- results in DNA MSI and inact of tumor suppressor genes
-inc risk of colorectal cancer, endometrial cancer
-dx suspected by tumor tissue immunohistochemical staining for MMR proteins or testing for MSI!!
-dx confirmed by genetic testing