Small Bowel and Colon DSA Flashcards
Noninfl diarrhea- viral, protozoal, bacterial enterotoxin production
- norovirus, rotavirus
- Giardia, Cryptosporidium, Cyclospora
- preformed enterotoxin- Staph aureus, Bacillus cereus, Clostridium perfringens
- Enterotoxin production- ETEC, Vibrio cholera
Infl diarrhea- viral, protozoal, cytotoxin production, mucosal invasion
- CMV
- Entamoeba histolytica
- 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
- lactose intolerance
- IBS
- previous gastric surgery or ileal resection
- parasitic infections
- medications
- systemic dz
- 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
- anti-IF ab’s
- achlorhydria leads to hypergastrinemia!!- 5% of pts develop carcinoid tumors
weight loss, m wasting- malabsorption of?
fat, protein, carbs
microcytic anemia- malabsorption of?
iron
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?
lactose
edema- malabsorption of?
protein
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?
- N europeans
- HLA-DQ2/8
Celiac dz- lab testing
- deficiencies
- 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
- multisystem dz
- 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
- abnormal motility
- visceral hypersensitivity
- enteric infection
- 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
Constipation- causes
- most common- inadequate fiber/fluid intake, poor bowel habits
- systemic dz- endocrine, metabolic, neurologic
- medications- opioids
- structural abnormalities
- slow colonic transit
- pelvic floor dyssynergia
- IBS
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
- handwashing!
Antibiotic-Associated Colitis- virulent strain
-NAP1- higher toxin A and B production
Antibiotic-Associated Colitis- sx
- mild-moderate greenish, foul-smelling watery diarrhea
- leukocytosis
- 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
Microscopic colitis
- idiopathic
- 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
- tx- loperamide
Diverticular Disease of the Colon
- uncomplicated diverticulosis
- diverticulitis
- diverticular bleeding
Uncomplicated diverticulosis
- 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
- leukocytosis
Diverticulitis- imaging
- empiric medical therapy first!
- colonoscopy or CT or barium enema- to exclude colonic neoplasms
Diverticulitis- complications
- fistula formation
- strictures- obstruction
Diverticular bleeding
-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)
- submucosal lesions
- 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
FAP- sx
- 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
- APC
- MUYTH
FAP- treatment
-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
- AD
- 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
Lynch Syndrome- Bethesda criteria
- colorectal cancer < 50 yo
- colorectal or Lynch syndrome-assoc tumor regardless of age (endometrial, stomach, ovary, pancreas, ureter and renal pelvis, biliary tract, brain)
- colorectal cancer with 1 or more first degree relatives with colorectal or lynch syndrome-related cancer occuring b/f age 50
- colorectal cancer with 2 or more second-degree relatives
- tumors with infiltrating lymphocytes, signet ring differentiation, or medullary growth pattern in pts < 60 yo
- should be genetically tested!!!
