This document provides a summary of key points about various topics related to colon and lower gastrointestinal diseases: 1) It discusses the anatomy and physiology of the colon, causes of ischemic colitis, treatments for Clostridium difficile and lower GI bleeding, and criteria for surgery for lower GI bleeding. 2) It reviews Ogilvie syndrome, sigmoid volvulus, cecal volvulus, diverticular disease, familial adenomatous polyposis, Lynch syndrome, Peutz-Jeghers syndrome, and inflammatory bowel diseases. 3) It covers screening recommendations, staging, treatment options for colon cancer and analyzes polyp types and criteria for surgery after polypectomy.

1. Colon ABSITE review

2. Basic science/Anatomy
• Fuel – SCFA (butyrate)
• 1st branch SMA – inferior pancreaticoduodenal
• Replaced RHA – Off SMA travels POSTERIOR
to portal vein – 12% incidence
• Watershed areas:
• Griffith’s = Splenic flexure
• Sudek’s = Recto-sigmoid junction
• Colon ABSORBS (Na and H2O) and Secretes
(K)

3. Ischemic Colitis
• Most are idiopathic
• High suspicion after aortic surgery
• Affects watershed regions first
• Dx: colonoscopy/flex sigmoidoscopy
• May need need surgical resection with second
look
• Rectal sparing due to IMA and iliac collaterals

4. Clostridium Difficile
• RF: Antibiotic use (classically clindamycin) and
immunocompromised
• Tx: oral metronidazole, oral vancomycin
• IV metronidazole
• Vancomycin emema
• Fecal transplant
• Subtotal colectomy

5. Lower GI Bleeding
• MC cause (after upper GI source) is diverticular
disease
• Vasa recta – arterial bleeding
• 50-90% from right side
• Angiodysplasia
• MC in elderly
• Right side
• Venous
• Aortic stenosis
• Heyde syndrome triad: aortic stenosis, coagulopathy, anemia
d/t bleeding from intestinal angiodysplasia

6. Lower GI Bleeding
• Indications for surgery:
• Transfusion of 4U PRBC in 24 hours
• Persistent bleeding after 72 hours
• Re-bleeding within one week
• Localization studies
• Angiography: 1-1.5cc/min
• Tagged RBC Scan: 0.1-0.5cc/min
• Capsule endoscopy
• Tech99 Meckel scan
• Push endoscopy
• No segmental resection without previous localization

7. Lower GI Bleeding
• Unstable despite resuscitation
• R/O UGI bleed (NGT) and hemorrhoids (anoscopy)
• On-table angiography for localization  segmental
resection
• Total abdominal colectomy if unable to localize

8. Ogilvie Syndrome
• Non-obstructive colonic dilation
• Elderly, debilitated, recent surgery (ortho total
joints), trauma, narcotic use
• Conservative Tx:
• bowel rest
• electrolyte correction (K, Mg)
• stop narcotics and anticholinergics

9. Ogilvie Syndrome
• Neostigmine after conservative management
• Increased acetylcholine activity
• 90% success rate (significant emotional event)
• Contraindicated: cardiovascular disease, severe
asthma, beta-blocker use
• Must have atropine at bedside for bradycardia
• Cecum >10-12 cm
• Cecostomy tube
• Subtotal colectomy with end ileostomy

10. Sigmoid Volvulus
• MC of colonic volvulus
• Bedridden, institutionalized neuro/psych patient
• Abd XR points toward RUQ (away from volvulus)
• Bent inner tube sign
• Coffee bean sign
• Barium enema reveals sigmoid bird’s beak
• Flexible sigmoidoscopy to reduce/detorse
• Then prep
• Then elective sigmoidectomy as long as pt stays hemodynamically stable and no recurrence in
meantime
• No sigmoidopexy because reccurence is too high
• If at any time perforation, peritonitis, gangrene, or failure of detorsion  need surgery
• Do not detorse if evidence of ischemia – will release inflammatory cytokines

11. Sigmoid Volvulus

12. Cecal Volvulus
• Similar presentation but less common
• Abd XR points toward LUQ (away from volvulus)
• Bent inner tube sign
• Coffee bean sign
• Barium enema shows bird’s beak
• Right hemicolectomy
• Cecopexy if poor candidates or due to cecal bascule

13. Cecal Volvulus

14. Diverticular Disease
• False diverticula – 90% in sigmoid (Western)
• >50% of people will get this
• Complicated Diverticulitis = Hinchey scale
• I: Confined pericolic abscess/inflammation
• II: Distant abscess (pelvic or retroperitoneal)
• III: Purulent peritonitis (surgical diagnosis)
• IV: Feculant peritonitis (surgical diagnosis)
• Treatment
• Uncomplicated: oral antibiotic to cover E.coli and anaerobes
• Complicated:
• Hinchey I-II: IV abx, IV fluids, NPO, perc drain abscess >4cm
• Elective resection in 6-12 weeks
• Hinchey III-IV: Surgical resection (Hartmann’s, primary anastomosis with/without diversion)

15. Diverticular Disease
• Elective Sigmoidectomy
• Resect all inflammed bowel and anastamose with rectum
• Do not removed non-inflamed diverticula
• Colovesicular fistula is the most common
• Pneumaturia, UTI, colonic resection with fistula closure
• Colovaginal fistula
• Hysterectomy, colonic resection with fistula closure and
vaginal defect repair

16. Familial Adenomatous
Polyposis
• Autosomal dominant, APC gene, 1000’s polyps
• 100% CA at age 50
• Annual screening at 10-12 y/o
• Prophylactic proctocolectomy at 20 y/o
• Sooner if villous or HGD
• Need total proctocolectomy, rectal mucosectomy, IPAA
• New Dx = colo, metastatic w/u, EGD, genetic testing
• Post-Op: Do NOT need yearly colonoscopy – just
yearly EGD and flex sigmoidoscopy

17. Familial Adenomatous
Polyposis
• FAP-associated tumors
• Desmoid – most common
• Duodenal adenocarcinoma
• Medulloblastoma (Turcot- CNS tumors)
• Hepatoblastoma
• Osteoma (Gardner- sebaceous cysts, osteomas)
• Thyroid
• Adrenal
• Death is from desmoid or duodenal carcinoma
• Bi-annual EGD after 25 y/o

18. Desmoid
• Occur at surgical sites from prior surgery
• Benign, rapid growth
• Treatment
• COX-2 – Sulindac
• Tamoxifen
• Imantinib
• Resection with negative margins (abdominal wall)

19. HNPCC/Lynch Syndrome
• Autosomal dominant; mismatch repair, microsatellite
instability
• Type I: Colon only
• Type II: Colon and other
• Fewer polyps(<100)
• Predilection for RIGHT sided colon carcinoma
• Associated with endometrial, ovarian, gastric, and small
bowel
• All get subtotal colectomy for cancer/dysplasia
diagnosis
• Consider TAH-BSO

20. HNPCC/Lynch
• Amsterdam Criteria (3:2:1)
• Three affected (one first-generation), two generations affected, one
diagnosed before 50 y/o
• Revised Bethesda Criteria for testing for MSI
• <50 y/o
• Colon and HNPCC associated cancer
• Evidence of MSI <60 y/o
• Colon cancer or HNPCC related cancer in first degree relative (<50)
• Colon cancer or HNPCC related cancer in 2 or more 1st-2nd relatives
(regardless of age)
• Colonoscopy yearly at age 20-25
• Screen for everything else at age 35 (CA-125, annual transvaginal
U/S, endometrial biopsy

21. Peutz-Jeghers Syndrome
• Autosomal Dominant
• Benign intestinal hamartomas and
mucocutaneous pigmentation
• General increased risk of cancer
• No prophylactic surgery

22. Familial Juvenile
Polyposis
• Autosomal Dominant
• Benign hamartomas and mucin-filled polyps
• Hamartomas are not pre-malignant
• Overall increased colon cancer risk

23. Cowden Syndrome
• Autosomal Dominant
• GI hamartomas and trichilemmomas
• Breast and thyroid cancer

24. Ulcerative Colitis
• HLA-B27, bimodal distribution, better with smoking,
spares anus, Jewish, continuous from rectum.
• Mucosal inflammation, spares anus, crypt abscesses
(non-caseating granulomas -Crohns)
• Bloody diarrhea, abdominal pain, fever, wt loss
• EIM – ank spond, PSC, uveititis, Pyoderma, arthritis,
FTT (MCC manifestation in children)

25. Ulcerative Colitis
• Medical Tx – 5-asa, Sulfasalazine, AZA,
cyclosporine, mesalamine, infliximab
• Toxic colitis/flares – fever, tachy, low hgb, high
WBC, increasing pain, >6 bloody BM
• TMC - above with colonic distention
• TX – NGT, IVF, Abx, steroids

26. Ulcerative Colitis
• Surgery if – toxic megacolon, perforation,
dysplasia, medical failure, prolonged steroids,
FTT, cancer
• Emergent surgery = TPC w/ end ileostomy
• Elective surgery = TPC w/ rectal mucosectomy
and IPAA or APR with end ileostomy (divert)
• Take down IPAA if 1) CA 2) refractory pouchitis 3)
incontinence
• Pouchitis – flagyl (MC complication after IPAA)

27. Ulcerative Colitis
• CA risk 1% per year
• Start surveillance at 10 yrs post Dx w/
colonoscopy and random biopsies
• FHX, young age, left-sided, PSC – resect @ 20yrs

28. Colon Cancer
• Scope at 50yo or 40 if fam Hx or 10yrs prior
• APC (TSG); K-ras (Oncg); DCC (TSG)-P53 (TSG)
• CEA – not for screening
• For progression, recurrence, chemo response
• Strep bovis, strep galollyticus, clost. Septicum
• Colonoscopy and CT and TRUS (best for T&N)

29. Colon Cancer
• T – 0)intra mucosal, HGD, in-situ 1)sub mucosa 2)into muscle 3)through
muscle/into sub serosa* 4) through serosa/other organs
• N – 1) 1-3nodes 2) >4 nodes ++ (need 12 nodes)
• M – mets
• Stage 1) into muscle no nodes
• Stage 2) past muscle no nodes*
• Stage 3) NODES a- into muscle b- past muscle c->4n++
• Stage 4) mets ++
• (* = Neo-adjuvant for rectal)
• (++ = post op chemo for colon CA)

30. Colon Cancer
• Tubular polyps
• MC, 5% malignant
• Tubulovillous
• 15% malignant
• Villous
• 40-60% malignant
• Sessile
• Metachronous polyps
• Hyperplastic polyps
• Left sided, benign

31. Colon Cancer
• Surgery after polypectomy
• Positive margin; deep stalk invasion
• Unclear margin
• Polyps >3cm
• Angiolymphatic invasion
• Grade 3 histology

32. Colon Cancer
• Colon CA 4-5 cm margins
• 2012 society of colorectal surgeons
• Rectal CA 2 cm margins
• Extension into other organs – En Bloc
resection

33. Colon Cancer
• Colon CA
• Stage 1 – formal resection and done
• Stage 2 – formal resection and chemo if <12 nodes,
LV invasion, perf, obstruction, or CEA
• Stage 3 – resect and chemo
• Stage 4 – resect and chemo (bevacizamab,
cituximab )
• Rectal CA
• Same but Stage 2 gets neo-adjuvant

34. Colon Cancer
• Anal Canal – dentate line to levator ani muscles
• Need 2 cm margin PROXIMAL to levator ani
• if 2 cm from levator ani muscles then can perform
LAR for rectal CA