Basic Science – “Large Bowel”. Anatomy Right colon Transverse colon Left colon Descending Sigmoid Rectum What defines the transition between the sigmoid.

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 absorption900ml of waterBile acidsSodium (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

ElectiveIntractability

Dysplasia, malignancy or malignancy prophylaxis

Complications of medications (usually steroids)

EmergencyToxic 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/GUSurgical 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!