Lecture 5 - Large Bowel Flashcards
what part of the GI has the highest bacterial load?
colon
most common watershed area of the colon? what 2 arteries?
splenic flexure;
SMA, IMA;
other watershed area = distal sigmoid colon (IMA and hypogastrics)
luminal caliber of the colon is larger on the ____, so few _____ symptoms from lesions here
right, obstructive
adenoma-carcinoma sequence:
1. normal colon becomes a _____ when the ____ gene is lost
colon at risk;
APC
adenoma-carcinoma sequence:
2. colon at risk becomes a ____ with a ____ mutation
adenoma, KRAS
KRAS gives poor prognosis
adenoma-carcinoma sequence:
3. adenoma becomes ______ with loss of _____
carcinoma;
p53 or other tumor suppressor
what drug may be protective in colorectal cancer?
NSAIDs
microsatelite:
mutations of _____ genes such as ______ –> ___ adenoma –> cancer
DNA repair, MLH1;
serrated
CRC: Left sided (descending) vs right sided (Ascending): bleeding = iron deficiency anemia = decreased stool caliber = partial obstruction = napkin ring lesion =
right; right; left; left; left
familial adenomatous polyposis (FAP): mode of inheritance? mutation in what gene? what chromosome? in addition to polyps, name 2 other cancers associated with this
autosomal dominance;
APC;
5;
duodenal, desmoid
Lynch syndrome:
also known as ____;
mutations in ______ genes;
associated with what 2 other cancers?
Hereditary nonpolyposis colorectal cancer;
DNA mismatch repair;
endometrial, ovarian
“microsatellite instabilty”
what type of polyp has the most malignant potential?
villous adenoma
CRC:
“____” lesion seen on barium enema;
what tumor marker is used to monitor recurrence?
apple core;
CEA
CRC:
most commonly used screening tool is ____:
Fecal immunochemical testing (FIT) detects presence of _____.
colonoscopy;
hemoglobin
fecal ocult blood testing is not the best
irritable bowel syndrome (IBS):
structural abnormalities seen = ____:
typically due to disturbed ____;
none;
motility
IBS:
recurrent _____ associated with 2 or more of the following = related to ____, changes in stool ____, or changes in stool _____;
pain improves following ____
abdominal pain;
defecation, frequency, consistency;
bowel movement/defecation
IBS treatment:
increase dietary _____;
_____ for diarrheal forms
fiber;
hyoscyamine (or dicyclomine)
IBS treatment for constipation:
_____ is a chloride channel activator;
_____ is a guanyate cyclase agonist
lubiprostone;
linaclotide
SSRIS and TCAs also indicated
diverticulosis:
true or false diverticuli?;
most common location;
occur where _____ _____ perforate the ____ ____
false;
sigmoid colon;
vasa recta, muscularis externa
diverticulitis: presents as \_\_\_\_ pain; usually due to \_\_\_\_; 2 potential complications? treatment =
LLQ;
fecalith;
abscess, fistula;
antibioitics
ischemic colitis:
_____ pain;
typically affects ____ patients;
____ sign on imaging due to mucosal edema
post-prandial/abdominal;
elderly;
thumb-print
acute mesenteric ischemia:
blockage of flow;
_____ infarct seen with ____ occlusion;
____ infarct seen with hypotension;
transmural infarct, embolic ( ie SMA or mesenteric vein);
mucosal infarct
acute mesenteric ischemia:
___ stools;
pain is described as …..;
which etiology has worst prognosis?
red currant jelly;
pain out of proportion to physical findings;
low flow
chronic mesenteric ischemia:
due to _____ of the celiac, SMA, or IMA;
____ pain
athersclerosis;
post-prandial
