Colorectal

• Colon actively secretes K and HCO3
• Superior rectal artery off IMA; Middle off internal iliac; Inferior off internal pudendal (off internal iliac)
• External sphincter innervated by inferior rectal branch of internal pudendal nerve and perineal branch S4
• Squamous cell CA of anal canal: Rx with Nigro protocol (chemo and RT), not surgery.  APR for recurrent disease.
• Tranformation of polyp to CA takes ~ 8 yrs.
• T1 (limited to submucosa) rectal adenoCA can be excised transanally; T2: 20% are node +, rec APR. Do not do transanal if poor differentiation, neuro/vasc invasion.
• Stage III colon CA (node +) gets chemo, no RT
• Stage II, III rectal CA gets chemo and RT
• 1/2 of colon CA has ras mutation, p53 absent in 85%, DCC (deleted in Colon CA) in 70%
• Familial adenomatous poylposis: Autosomal dominant, CA by age 40; APC gene. Need total colectomy prophylactically. HaveUGI polyps as well, need to survey duodenum for CA. Also develop desmoids - benign, but very difficult to manage. Sulindac makes polyps receed.
• Lynch I Right sided, multiple CA's, young; Lynch II associated with CA of ovary, bladder, stomach
• Both Lynch (aka Herediatry Non Polyposis Colon CA) associated with DNA mismatch repair gene. Amsterdam criteria: 3 first degree relatives, over 2 generations.
• Gardner's syndrome: colon CA and desmoid tumors
• Turcot's syndrome: colon CA and brain tumors
• Peutz Jeghers: polyposis (not colon CA) and mucocutanous pigmentation
• Sigmoid Volvulus: decompress with scope, prep bowel, do sigmoid colectomy that admission
• Cecal volvulus (much less common): likely will not decompress; take to OR, most recommend R Hemicolectomy with ileo-transverse anastomosis although some try cecopexy
• Carcinoid of Appendix: > or = to 2cm or involving base = do R hemicolectomy, otherwise apendectomy only
• If operating for appy, find normal appy and Crohn's disease, take appendix (unless cecum very inflammed). Does not increase fistula rate
• Perianal abscess in Crohn's: incision and drainage as with any abscess
• In Ulcerative Colitis, proctocolectomy does not help sclerosing cholangitis, may help skin, anemia; rarely help arthritis
• HLA B27 associated with sacroilitis
• Pouchitis: Rx with Flagyl or short chain fatty acid enemas
• Pyoderma Gangrenosum: Rx with Dapsone and/or steroids (topical or systemic)
• Fissure in ANO 10% anterior in women, nearly all others posterior midline. Rx sitz baths, regular loose BM (water, fiber); persists then Lateral Internal Sphincterotomy. Some try nitroglycerine creams (increase O2 for ischemia) or botox (relax sphincter). Fissure not in midline, think IBD, TB, syphilis
• Bowen's Diease - intraepithelial squamous cell carcinoma, only 5% invasive. Wide Local Excision
• Perianal Paget's - rare intraepidermal neoplasm of apocrine glands, long pre-invasive phase. +PAS stain.
• 1/4 of patients with colonic AVM have aortic stenosis (1/2 have CAD)
• Campylobacter infectious colitis: may see aphthous ulcers on colonoscopy

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