Colorectal

Question 1

MCC of lower GIB in adults

Answer 1

Colonic diverticular disease

Question 2

Most sensitive radiographic test for GIB

Answer 2

radionuclide bleeding scan
Detects bleeding at rate of 0.1-0.5mL/min
2 types: technetium-99 sulfur colloid & pertechnetate-labeled autologous RBCs

requires active bleeding to detect source, bad for localization

Question 3

CEA

Answer 3

Carcinoembryonic antigen

Tumor marker associated with colon cancer

utility: eval postop mets or recurrence

Baseline level checked preop. Normal value seen in colon cancer, still needs to be followed postop.

Normal tissues produce CEA during development, stop before birth

Question 4

Treatment for CR adenocarcinoma

Answer 4

Tis, T1, T2 or no nodal involvement (Stage I): surgery

T3 or above +/- LNs (Stage II+): neoadjuvant chemo + surgery

Upper rectum: LHC
Middle/lower rectum: LAR
Close to anal sphincters/lower rectum w/ no oncological clearance possible: APR
T1 rectal CA w/in 8cm of anal verge, <3cm in size, well-differentiated, <30% circumference, mobile, nonfixed: transanal local excision

Question 5

Nerve injury during colorectal resection and anastomosis

Answer 5

Superior hypogastric plexus - fibers from lumbar sympathetic nerves, pass anterior to aorta, network near takeoff of IMA. Divides into L & R hypogastric nerves. Damage causes urinary incontinence & retrograde ejaculation.

Hypogastric nerves join w/ parasympathetic fibers of pelvic splanchnic nerves (S2-4) forms inferior hypogastric plexus. Nerves cont to rectum, bladder, prostate, seminal vesicles. Injury causes urinary incontinence and inability to obtain erection.

Question 6

L colectomy, inability to ejaculate postop, what was injured?

Answer 6

superior hypogastric plexus

Question 7

L colectomy, inability to obtain erection postop, what was injured?

Answer 7

pelvic splanchnic nerves

Question 8

LHC antibiotic ppx in pt w/ severe PCN allergy

Answer 8

Clinda/Flagyl + aminoglycosides (-mycins)/fluoroquinolone (-floxacin)
Clinda + Aztreonam

Question 9

Reversal of protective ileostomies

Answer 9

8-12 weeks
Pouchogram not mandatory
Decrease consequence of pelvic sepsis from anastomotic leaks but not necessarily the incidence of anastomotic leaks
If pt requires chemo, ileostomy reversed after completion of chemo

Question 10

Chronic UC w/ invisible high-grade dysplasia

Answer 10

Rec referral for repeat endoscopy with high-def colonoscopy + chromoendoscopy, targeted & random biopsies w/in 3-6 months

if HGD confirmed or multifocal low-grade dysplasia seen then total proctocolectomy indicated

Question 11

UC malignancy potential

Answer 11

Increases with time after diagnosis
1-2% at 10 years
2-8% at 20 years

Screening colo 8 yrs after dz onset
High-risk pts (PSC, stricture, hx of dysplasia): yearly colo
Random bx: 4-quadrant biopsies taken 10-cm intervals w/ total of >=32 bx
Directed bx: high-def chromoendoscopy (methylene blue, indigo carmine, Lugol’s solution)

Question 12

Colonic carcinoid tumor

Answer 12

Carcinoid histo: neuroendocrine cells, bland cytology, rare mitoses, + chromogranin

Colon carcinoid: worse overall prognosis, R-sided predominance, asxs until locally advanced/mets

Mets: LNs or liver

Tx: segmental colectomy + regional lymphadenopathy, mets resected; unresectable dz: ablation & embolization, octreotide to control tumor growth and sxs of hormone secretion

Question 13

Diverticular disease

Answer 13

MC on R side
Self-limiting
Colonoscopy if not actively bleeding for localization.
Surgery is indicated if HD unstable or if >4u required for resuscitation

less common cause of LGIB - AVMs (assoc w/ aortic stenosis - need echo)