Small Bowel and Colon DSA

Question 1

Noninfl diarrhea- viral, protozoal, bacterial enterotoxin production

Answer 1

• norovirus, rotavirus
• Giardia, Cryptosporidium, Cyclospora
• preformed enterotoxin- Staph aureus, Bacillus cereus, Clostridium perfringens
• Enterotoxin production- ETEC, Vibrio cholera

Question 2

Infl diarrhea- viral, protozoal, cytotoxin production, mucosal invasion

Answer 2

• CMV
• Entamoeba histolytica
• Cytotoxin production- EHEC, Vibrio parahaemylyticus, C difficile
• Mucosal invasion- shigella, campylobacter, salmonella, EIEC, others

Question 3

Initial diagnostic tests

Answer 3

• 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

Question 4

chronic diarrhea- exclude? tests?

Answer 4

• 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

Question 5

chronic diarrhea- Lab tests

Answer 5

• serologic tests for neuroendocrine tumors

- breath test- dx small bowel bacterial overgrowth

Question 6

Pernicious Anemia Gastritis

Answer 6

• 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

Question 7

weight loss, m wasting- malabsorption of?

Answer 7

fat, protein, carbs

Question 8

microcytic anemia- malabsorption of?

Answer 8

iron

Question 9

macrocytic anemia- malabsorption of?

Answer 9

vit B12 or folic acid

Question 10

paresthesia, tetany, Trousseau and Chvostek signs- malabsorption of?

Answer 10

-Calcium, Vit D, magnesium

Question 11

bone pain, fractures, skeletal deformities- malabsorption of?

Answer 11

calcium, vit D

Question 12

bleeding tendency (ecchymoses, epistaxis)- malabsorption of?

Answer 12

-Vit K (prolonged PT or INR)

Question 13

Milk intolerance (cramps, bloating, diarrhea)- malabsorption of?

Answer 13

lactose

Question 14

edema- malabsorption of?

Answer 14

protein

Question 15

Celiac Dz- essentials of diagnosis

Answer 15

• 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

Question 16

Celiac dz- in who?

Answer 16

• N europeans

- HLA-DQ2/8

Question 17

Celiac dz- lab testing

Answer 17

• deficiencies
• IgA tTG ab!!
• confirmation- mucosal biopsy- intraepit lymphocytes

Question 18

Celiac dz- treatment

Answer 18

• removal of gluten from diet

- dietary supplements (short-term)

Question 19

Whipple Disease- essentials of diagnosis

Answer 19

• multisystem dz
• fever, lymphadenopathy, arthralgias
• weight loss! (most common sx), malabs, chronic diarrhea
• duodenal biopsy with PAS-positive macrophages with characteristic bacillus

Question 20

Whipple disease- caused by? in who?

Answer 20

• Tropheryma whipplei (bacillus)

- white men; 40-60’s

Question 21

Whipple disease- dx

Answer 21

-endoscopic biopsy of duodenum- shows infiltration of lamina propria with PAS-positive macrophages that contain gram-positive bacilli

Question 22

Short Bowel Syndrome- causes

Answer 22

• 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

Question 23

terminal ileal resection

Answer 23

• malabs of bile salts and vit B12

- no bile salts- steatorrhea and malabs of fat-soluble vitamins

Question 24

extensive small bowel resection

Answer 24

• weight loss and diarrhea due to nutrient, water, and electrolyte malabsorption
• if have less than 100-200 cm of proximal jejunum- require parenteral nutrition

Question 25

Lactase Deficiency- essentials of diagnosis

Answer 25

- 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

Question 26

Lactase Deficiency- in who?

Answer 26

-90% asian ams, 70% Af ams, 95% native ams, 50% mexican ams, 60% jewish ams, <25% of white adults

Question 27

Lactase Deficiency- lab findings

Answer 27

-hydrogen breath test!

Question 28

Irritable Bowel Syndrome- essentials of diagnosis

Answer 28

- 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

Question 29

Irritable Bowel Syndrome- defined as?

Answer 29

- 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!)

Question 30

Irritable bowel syndrome- pathogenesis

Answer 30

- abnormal motility - visceral hypersensitivity - enteric infection - psychosocial abnormalities (50% have depression, anxiety, or somatization)

Question 31

Irritable bowel syndrome- treatment

Answer 31

- reassurance, education, support - explain mind-gut interaction- visceral motility and sensitivity changes can be exacerbated by environmental, social, or psyhological factors

Question 32

Constipation- causes

Answer 32

- 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

Question 33

Fecal Impaction- predisposing factors, presentation

Answer 33

- 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

Question 34

Antibiotic-Associated Colitis- essentials of diagnosis

Answer 34

- 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

Question 35

Antibiotic-Associated Colitis- caused by

Answer 35

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!

Question 36

Antibiotic-Associated Colitis- virulent strain

Answer 36

-NAP1- higher toxin A and B production

Question 37

Antibiotic-Associated Colitis- sx

Answer 37

- mild-moderate greenish, foul-smelling watery diarrhea - leukocytosis - severe/fulminant dz occurs in 10%- fever, hemodynamic instability, abd distension and pain

Question 38

Antibiotic-Associated Colitis- exam

Answer 38

- 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

Question 39

Microscopic colitis

Answer 39

- 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

Question 40

Diverticular Disease of the Colon

Answer 40

- uncomplicated diverticulosis - diverticulitis - diverticular bleeding

Question 41

Uncomplicated diverticulosis

Answer 41

- 90% of pts with diverticulosis have uncomplicated dz and no sx!! - usually an incidental finding - tx- high-fiber diet

Question 42

Diverticulitis- essentials of diagnosis

Answer 42

- acute abd pain and fever - left lower abd tenderness and mas - leukocytosis

Question 43

Diverticulitis- imaging

Answer 43

- empiric medical therapy first! | - colonoscopy or CT or barium enema- to exclude colonic neoplasms

Question 44

Diverticulitis- complications

Answer 44

- fistula formation | - strictures- obstruction

Question 45

Diverticular bleeding

Answer 45

-diverticulosis causes 1/2 of all cases of acute lower GI bleeding!

Question 46

polyps of the colon

Answer 46

- mucosal adenomatous polyps - mucosal serrated polyps (hyperplastic, sessile serated) - mucosal nonneoplastic polyps (juvenile, hamartomas, infl) - submucosal lesions * 70% are adenomatous

Question 47

Nonfamilial adenomatous and serrated polyps

Answer 47

- in 30% of adults > 50 yo - 95% of adenocarcinomas arise from these lesions! - inact of APC gene - adenoma > 1cm, dysplasia- advanced!

Question 48

Nonfamilial adenomatous and serrated polyps- fecal occult blood or multitarget DNA tests

Answer 48

- FOBT, FIT, fecal DNA tests- screening | - Cologuard- fecal DNA test with test for stool hemoglobin

Question 49

Nonfamilial adenomatous and serrated polyps - radiologic tests

Answer 49

-polyps IDed by barium enema exams or CT colonography

Question 50

Nonfamilial adenomatous and serrated polyps- endoscopic tests

Answer 50

- colonoscopy- best way of detecting and removing adenomatous and serrated polyps - done in all pts who have positive FOBT, FIT, fecal, or DNA tests

Question 51

Familial Adenomatous Polyposis- essentials of diagnosis

Answer 51

- 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

Question 52

FAP- sx

Answer 52

- 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

Question 53

FAP- genetic testing

Answer 53

- APC | - MUYTH

Question 54

FAP- treatment

Answer 54

-complete proctocolectomy with ileoanal anastomosis or colectomy with ileorectal anastomosis!!- b/f age 20!

Question 55

Hamartomatous Polyposis Syndromes

Answer 55

- Peutz-Jeghers syndrome (AD- polyps, mucocutaneous pigment, 40% chance of malignancy) - Familial juvenile polyposis (AD- several polyps in colon, 50% risk of adenocarcinoma)

Question 56

Lynch syndrome (HNPCC)- essentials of diagnosis

Answer 56

- 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

Question 57

Lynch Syndrome- Bethesda criteria

Answer 57

- 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!!!