Lecture 5 - Large Bowel

Question 1

what part of the GI has the highest bacterial load?

Answer 1

colon

Question 2

most common watershed area of the colon? what 2 arteries?

Answer 2

splenic flexure;
SMA, IMA;

other watershed area = distal sigmoid colon (IMA and hypogastrics)

Question 3

luminal caliber of the colon is larger on the ____, so few _____ symptoms from lesions here

Answer 3

right, obstructive

Question 4

adenoma-carcinoma sequence:

1. normal colon becomes a _____ when the ____ gene is lost

Answer 4

colon at risk;

APC

Question 5

adenoma-carcinoma sequence:

2. colon at risk becomes a ____ with a ____ mutation

Answer 5

adenoma, KRAS

KRAS gives poor prognosis

Question 6

adenoma-carcinoma sequence:

3. adenoma becomes ______ with loss of _____

Answer 6

carcinoma;

p53 or other tumor suppressor

Question 7

what drug may be protective in colorectal cancer?

Answer 7

NSAIDs

Question 8

microsatelite:

mutations of _____ genes such as ______ –> ___ adenoma –> cancer

Answer 8

DNA repair, MLH1;

serrated

Question 9

CRC: Left sided (descending) vs right sided (Ascending):
bleeding = 
iron deficiency anemia = 
decreased stool caliber = 
partial obstruction = 
napkin ring lesion =

Answer 9

right;
right;
left;
left;
left

Question 10

familial adenomatous polyposis (FAP):
mode of inheritance?
mutation in what gene?
what chromosome?
in addition to polyps, name 2 other cancers associated with this

Answer 10

autosomal dominance;
APC;
5;
duodenal, desmoid

Question 11

Lynch syndrome:
also known as ____;
mutations in ______ genes;
associated with what 2 other cancers?

Answer 11

Hereditary nonpolyposis colorectal cancer;
DNA mismatch repair;
endometrial, ovarian

“microsatellite instabilty”

Question 12

what type of polyp has the most malignant potential?

Answer 12

villous adenoma

Question 13

CRC:
“____” lesion seen on barium enema;
what tumor marker is used to monitor recurrence?

Answer 13

apple core;

CEA

Question 14

CRC:
most commonly used screening tool is ____:
Fecal immunochemical testing (FIT) detects presence of _____.

Answer 14

colonoscopy;
hemoglobin

fecal ocult blood testing is not the best

Question 15

irritable bowel syndrome (IBS):
structural abnormalities seen = ____:
typically due to disturbed ____;

Answer 15

none;

motility

Question 16

IBS:
recurrent _____ associated with 2 or more of the following = related to ____, changes in stool ____, or changes in stool _____;
pain improves following ____

Answer 16

abdominal pain;
defecation, frequency, consistency;
bowel movement/defecation

Question 17

IBS treatment:
increase dietary _____;
_____ for diarrheal forms

Answer 17

fiber;

hyoscyamine (or dicyclomine)

Question 18

IBS treatment for constipation:
_____ is a chloride channel activator;
_____ is a guanyate cyclase agonist

Answer 18

lubiprostone;
linaclotide

SSRIS and TCAs also indicated

Question 19

diverticulosis:
true or false diverticuli?;
most common location;
occur where _____ _____ perforate the ____ ____

Answer 19

false;
sigmoid colon;
vasa recta, muscularis externa

Question 20

diverticulitis:
presents as \_\_\_\_ pain;
usually due to \_\_\_\_;
2 potential complications?
treatment =

Answer 20

LLQ;
fecalith;
abscess, fistula;
antibioitics

Question 21

ischemic colitis:
_____ pain;
typically affects ____ patients;
____ sign on imaging due to mucosal edema

Answer 21

post-prandial/abdominal;
elderly;
thumb-print

Question 22

acute mesenteric ischemia:
blockage of flow;
_____ infarct seen with ____ occlusion;
____ infarct seen with hypotension;

Answer 22

transmural infarct, embolic ( ie SMA or mesenteric vein);

mucosal infarct

Question 23

acute mesenteric ischemia:
___ stools;
pain is described as …..;
which etiology has worst prognosis?

Answer 23

red currant jelly;
pain out of proportion to physical findings;
low flow

Question 24

chronic mesenteric ischemia:
due to _____ of the celiac, SMA, or IMA;
____ pain

Answer 24

athersclerosis;

post-prandial

Question 25

chronic mesenteric ischemia:

weight _____ due to sitophobia, which is _____

Answer 25

loss;

aversion to food