Colorectal Flashcards
Radition therapy
colon v rectal, which stage
Rectal is more responsive to radiation
- Neoadj chemorads at Stage II for rectal ca
- Adjuvant for Stage III colon (5-FU, Leuovorin, Oxaliplatin)
Transanal excision rectal cancer
Only pts that aren’t surgical candidates (APR, LAR)
- higher recurrence rates
- T1 lesion, <3cm in size, <30% circumference, <8cm from anal verge, no lymphovasc invasion, no mucin production
Vasa recta
Arterial supply of colon wall, diverticulum
- #1 cause LGIB
(2- bleeding polyps)
TNM (colorectal)
T0: contained by basement membrane (carcinoma in situ) T1: invades submucosa T2: invades muscularis propria T3: into pericolorectal tissues t4a: surface of visceral peritoneum T4b: other organs
N1a: 1 regional LN
N1b: 2-3 regional LN
N2a: 4-6 regional LN
N2b: >7 regional LN
M1a: mets
Stage IIa: T3,N0,M0 Stage IIb: T4a,N0,M0 Stage III A: T1-T2,N1,M0, or T1,N2a,M0 Stage IIIB: Stage IIIC: T4a,N2a,M0, T3-T4a,N2b,M0, or T4b,N1-N2,M0
LGIB- primary intervention
NGT, resuscitate
Rectal cancer workup
- pt p/w mass palpable at lower aspect of rectum
- Proctoscopy to visualize extent of involvement
- CEA, LFTs, full cscope to eval syncrhonous lesions, CT scan for metastatic disease
- MRI or EUS to stage depth of tumor and nodal involvement
(PET is expensive and not routinely used)
Diverticular bleed
- R/o UGIB with NGT
- If stable cscope, angiography, tagged RBC scan
- If unstable or requires >4U PRBC, OR
IBD flare
Stop all antimotility agents, opiates, anticholinergics
- initial tx stable patient: steroids
- if e/o perforation, massive hemorrhage, peritonitis with worsening sepsis -> subtotal colectomy with end ileostomy
- at later date need completion proctectomy with IPAA
Main fuel source for colonocytes v enterocytes
Colonocytes: short chain fatty acids
Enterocytes: glutamine
Distances from anal verge
Dentate line, anorectal ring, lower third, middle third, upper third, rectosigmoid junction,
Dentate line - 2 cm Anorectal ring - 4 cm Lower third - 4-8 cm Middle third - 8-12 cm Upper third - 12-16 cm Rectosigmoid junction 15-18 cm
Portal versus systemic venous drainage
- superior, middle, lower rectum
IMV -> splenic v -> portal vein
- Superior and middle rectum -> IMV; IMA nodal lymphatics
- Lower rectum -> internal iliac vv; IMA or internal iliac nodes
Pouchitis
- cause, symptoms, treatment
- stump pouchitis tx
Cause: mucosal inflammation
Sx: fever, chills, diarrhea
Tx: Cipro/Flagyl, budesonide enemas; if refractory, r/o other causes, pouch excision, end ileostomy
- Stump pouchitis need short-chain fatty acid enemas’
External sphincter
- muscle, innervation
Puborectalis muscle (striated muscle, continuation of levator ani muscle) Internal pudendal nerve (CNS- voluntary control)
Internal sphincter
- muscle, innervation
Continuation of the muscularis propria (smooth muscle)
Contracted at baseline
Colonic intertia
- Tx
Tx: subtotal colectomy
