Basic Science – “Large Bowel”

Anatomy Right colon Transverse colon Left colon Descending Sigmoid Rectum What defines the transition between the sigmoid colon and rectum?

Colon - Anatomy What are the layers of the bowel wall? What comprises the tenia?

Colon – Arterial Supply & Lymphatic Drainage

Rectum - Anatomy

Rectum – Venous and Lymphatic Drainage

Colon - Physiology What is the primary role of the colon? Fluid absorption 900ml of water Bile acids Sodium (active transport)

Colonic transit R colon: segmental propulsive & retropulsive contractions for “mixing” L colon: mostly propulsive contractions “Mass movements”: large peristaltic contractions (1-3/day) that move contents about 1/3 the length of the colon

Defecation Distention of the rectum triggers the rectoanal inhibitory reflex (RAIR): External anal sphincter voluntarily relaxed Rectum / Distal colon contract Pelvic floor relaxes (straightening of rectosigmoid angle)

Diverticular Disease True or false diverticula?

Acute Diverticulitis (simple) Symptoms LLQ abdominal pain/fever/leukocytosis Radiologic evaluation CT scan Treatment Bowel rest & IV ABX Duration of both?

Acute Diverticulitis (simple) Management after resolutions of symptoms: BE or Colonoscopy 6-8 wks later Discussion re: surgical intervention What are the proximal and distal margins in an elective resection for diverticulosis?

Complicated Diverticulitis Perforation Abscess/Phlegmon/Peritonitis Obstruction Acute inflammation vs. fibrosis Fistula Colovesical/Colovaginal Bleeding

Complicated Diverticulitis - Management Perforation With contained abscess With peritonitis Obstruction Acute Chronic Fistula Bleeding

Ulcerative Colitis Inflammatory condition of the colon and rectum limited to the mucosa and submucosa Etiology: unknown Age of onset: Bimodal distribution

Ulcerative Colitis Disease begins at the dentate line and move proximally without skip areas 75% confined to proctosigmoiditis Symptoms: Numerous bloody bowel movements “no blood, no UC” Abdominal pain and cramps Tenesmus, fecal urgency & incontinence

Ulcerative Colitis – Endoscopic Findings

Ulcerative colitis – Medical Management Tailored to disease severity Mild –Moderate disease Sulfasalazine and its derivatives (mesalamine based compounds) Immunosuppressives (6-MP, Azathioprine) Severe disease Corticosteroids Cyclosporine A

Ulcerative colitis – Indications for surgery Elective Intractability Dysplasia, malignancy or malignancy prophylaxis Complications of medications (usually steroids) Emergency Toxic colitis Hemorrhage Acute exacerbation unresponsive to medical Tx

Ulcerative Colitis – Surgical options Emergency Subtotal colectomy with end-ileostomy Elective Proctocolectomy + End ileostomy IPAA Koch pouch

Ulcerative colitis -IPAA

Crohns Disease Inflammatory condition of the GI tract of unknown etiology Bimodal distribution “mouth to anus” Skip areas Transmural Non-caseating granulomas

Crohns Disease - symptoms Crampy abdominal pain Watery diarrhea Fecal urgency and tenesmus

Crohns Colitis – Endoscopic features Skip areas – often with rectal sparing “cobblestone” appearance Serpigenous ulcerations

Crohns disease -Treatment Medical management is the mainstay of Crohns disease: Mild / Moderate disease: 5-ASA compounds Severe disease: Steroids 6-Mp and Azathioprine for maintenance

Crohns disease - complications Abscess Fistula Perforation Toxic colitis Obstruction Colonic stricture = malignancy

Crohns Disease - Surgery Goal: To palliate the symptoms Location and extent of disease determine operative procedure in Crohns colitis: Segmental resection vs. proctocolectomy

Large Bowel Obstruction Etiology: Colon cancer (Left-sided) Volvulus (cecal & sigmoid) Diverticulosis

Large Bowel Obstruction - Presentation Symptoms Obstipation, abdominal pain and distention, +/- emesis Physical Exam Abdominal distention, tenderness,

Large Bowel Obstruction - Management Resuscitation X-Rays… Plain films Retrograde GGE CT scan …vs. Endoscopy

What is this?

Large Bowel Obstruction - Management Sigmoid Volvulus Cecal volvulus Malignancy (Left side) Hartmann procedure Resection/ on-table lavage/ primary anastomosis Subtotal + anastomosis ? Stent

Colon cancer – Inherited Familial adenomatous polyposis Autosomal Dominant (APC gene: 5q21) Scattered polyps to “carpeted” 100% lifetime risk of developing cancer without surgery Extraintestinal manifestations (Gardner’s syndrome) Desmoids/CHRPE/periampullary ca/epidermal cysts

Colon cancer – Inherited FAP – Surgical treatment Proctocolectomy with End ileostomy IPAA Subtotal colectomy / IRA +/- Sulindac

Colon cancer – Inherited HNPCC (Lynch Syndrome) Autosomal dominant Germline mutation in DNA mismatch repair genes (hMLH1, hMSH2) Scattered polyps with tendency toward proximal lesions 80% lifetime risk of developing colon cancer Amsterdam criteria Extracolonic malignancies Endometrial/Ovarian/GU Surgical management: Subtotal / IRA

Colon cancer - polyps Non-neoplastic Hyperplastic Juvenile Inflammatory Neoplastic potential Villous adenoma Tubular adenoma Tubulovillous adenoma Which has the highest malignant potential?

Colon cancer – Sporadic Adenoma to carcinoma:

Cancer in a polyp…

Colon cancer - presentation Bleeding Anemia Guaiac + Obstruction Screening

Colon cancer – pre-op evaluation Family history! CEA Colonoscopy Tissue for diagnosis Evaluate remainder of colon Abdominal/Pelvic CT scan ? PET scan

Colon cancer - staging

Colon cancer – adjuvant therapy Stage III 5-FU / Leucovorin based ? Stage II with adverse features Poorly differentiated LVI Obstruction/Perforation

Colon cancer - surveillance No survival benefit with aggressive surveillance strategies!