Large Bowel

Question 1

colitis types

Answer 1

bowel wall thickening

infectious, ischemic, pseudomembranous, ulcerative, typhilitis

Question 2

colonic ischemia

Answer 2

acute arterial thrombus, chronic arterial stenosis, low flow states (CHF), venous thrombosis

splenic flexure most susceptible

rectum has dual blood supply; hardly ever ischemic (superior rectal artery, and inferior/middle rectal rectal arteries)

Question 3

ischemic colitis findings

Answer 3

segmental, continuous thickening of colon in vascular distribution; sparing of rectum

evaluate for atherosclerotic disease, left atrial thrombus

Question 4

cause of infectious colitis

Answer 4

bacterial, TB, viral, amoebic

right colon: yersinia, salmonella, colonic TB (and ileocecal valve)

pancolitis: e. coli, CMV, C diff

pericolonic fat stranding, ascites, colonic wall thickening

Question 5

pseudomembranous colitis

Answer 5

infectious coliits; overgrowth of C diff due to alteration of gut flora

pancolitis; accordion sign and thumbprinting

Question 6

ulcerative colitis

Answer 6

inflammatory bowel disease; begins in rectum and spreads proximally (NO skip lesions); does not extend more proximally than cecum (backwash ileitis)

associated with PSC, colon cancer, cholangiocarcinoma

Question 7

extra abdominal manifestations of UC

Answer 7

sacroilitis, iritis, erythema nodosum (tender red subcutaneous nodules), pyoderma gangrenosum (cutaneous ulcers)

Question 8

imaging findings of UC

Answer 8

circumferential wall thickening with granular mucosal pattern; pseudopolyps

collar butten ulcer

lead pipe colon

toxic megacolon

Question 9

typhilitis/neutropenic enterocoiltis

Answer 9

right sided colitis in immunocompromised patients

treat with abx and antifungals

Question 10

polyposis syndromes affecting the bowel

Answer 10

FAP, hereditary nonpolyposis colon cancer syndrome (Lynch), peutz jeghers, cowden syndrome, cronkhite canada

Question 11

FAP

Answer 11

AD syndrome with innumerable premalignant adenomatous polyps

treatment: prophylactic colectomy

Question 12

gardner syndrome

Answer 12

variant of FAP

polyps + desmoid tumors + osteomas + papillary thyroid cancer + epidermoid cysts

Question 13

turcot syndrome

Answer 13

variant of FAP

polyps + CNS tumors (glioma/medulloblastomas)

Question 14

hereditary nonpolyposis colon cancer/Lynch syndrome

Answer 14

AD polyposis caused by DNA mismatch repair and microsatellite instability on molecular level

adenomatous colon polyps

associated with endometrial, stomach, small bowel, liver, biliary malignancies

Question 15

cowden syndrome

Answer 15

AD of multiple hamartomatous polyps in skin and external mucous membranes

increased risk of thryoid cancer (follicular), skin, oral, breast, uterine malignancies

Question 16

cronkhite canada

Answer 16

non inherited polyposis with hamartous polyps through GI tract

associated with abnormal skin pigmentation, alopecia, onychodystropy (malformation of nails)

Question 17

appendicitis

Answer 17

obstruction of appendix leading to venous congestion, mural ischemia, bacterial translocation;

tip appendicitis to gangrenous appendicitis with abscess

Question 18

imaging findings of appendicitis

Answer 18

distended fluid filled appendix > 6mm, appendiceal wall thickening, appendicolith

indirect: periappendiceal at stranding, cecal wall thickening, hydroureter, small bowel ileus

noncompressibility of appendix on US

Question 19

diverticulitis

Answer 19

microperforation/inflammation of colonic diverticulum

usually affects left colon > right

Question 20

uncomplicated vs complicated diverticulitis

Answer 20

uncomplicated: bowel wall thickening, pericolonic fat stranding around diverticulum
complicated: periconolic/hepatic abscess, extraluminal air, bowel obstruction, bowel fistula, mesenteric venous thrombis

Question 21

indications for diverticulitis surgery

Answer 21

fistula, recurrent diverticulitis with 2 prior episodes of diverticulitis treated conservatively

Question 22

epiploic appendagitis

Answer 22

benign mimic of diverticulitis caused by torsion of fatty tag/appendage from colon

oval fat attenuating lesion abutting normal colon wall with mild fat stranding