Basic Science – “Large Bowel”
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Transcript of Basic Science – “Large Bowel”
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Basic Science – “Large Bowel”
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Anatomy
Right colon Transverse colon Left colon
Descending Sigmoid
Rectum What defines the
transition between the sigmoid colon and rectum?
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Colon - Anatomy
What are the layers of the bowel wall?
What comprises the tenia?
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Colon – Arterial Supply & Lymphatic Drainage
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Rectum - Anatomy
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Rectum – Venous and Lymphatic Drainage
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Colon - Physiology What is the primary role of the colon?
Fluid absorption900ml of waterBile acidsSodium (active transport)
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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
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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)
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Diverticular Disease
True or false diverticula?
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Acute Diverticulitis (simple) Symptoms
LLQ abdominal pain/fever/leukocytosis
Radiologic evaluation CT scan
Treatment Bowel rest & IV ABX
Duration of both?
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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?
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Complicated Diverticulitis Perforation
Abscess/Phlegmon/Peritonitis Obstruction
Acute inflammation vs. fibrosis Fistula
Colovesical/Colovaginal Bleeding
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Complicated Diverticulitis - Management
Perforation With contained abscess With peritonitis
Obstruction Acute Chronic
Fistula Bleeding
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Ulcerative Colitis Inflammatory condition of the
colon and rectum limited to the mucosa and submucosa
Etiology: unknown Age of onset: Bimodal distribution
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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
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Ulcerative Colitis – Endoscopic Findings
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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
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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
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Ulcerative Colitis – Surgical options
Emergency Subtotal colectomy with end-
ileostomy Elective
Proctocolectomy + End ileostomy IPAA Koch pouch
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Ulcerative colitis -IPAA
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Crohns Disease Inflammatory condition of the GI
tract of unknown etiology Bimodal distribution “mouth to anus” Skip areas Transmural Non-caseating granulomas
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Crohns Disease - symptoms
Crampy abdominal pain Watery diarrhea Fecal urgency and tenesmus
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Crohns Colitis – Endoscopic features Skip areas – often with rectal sparing “cobblestone” appearance Serpigenous ulcerations
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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
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Crohns disease - complications
Abscess Fistula Perforation Toxic colitis
Obstruction Colonic stricture = malignancy
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Crohns Disease - Surgery
Goal: To palliate the symptoms Location and extent of disease
determine operative procedure in Crohns colitis: Segmental resection vs.
proctocolectomy
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Large Bowel Obstruction Etiology:
Colon cancer (Left-sided)
Volvulus (cecal & sigmoid)
Diverticulosis
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Large Bowel Obstruction - Presentation
Symptoms Obstipation, abdominal pain and
distention, +/- emesis Physical Exam
Abdominal distention, tenderness,
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Large Bowel Obstruction - Management
Resuscitation X-Rays…
Plain films Retrograde GGE CT scan
…vs. Endoscopy
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What is this?
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Large Bowel Obstruction - Management
Sigmoid Volvulus Cecal volvulus Malignancy (Left side)
Hartmann procedure
Resection/ on-table lavage/ primary anastomosis
Subtotal + anastomosis
? Stent
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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
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Colon cancer – Inherited FAP – Surgical treatment
Proctocolectomy with End ileostomy IPAA
Subtotal colectomy / IRA +/- Sulindac
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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
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Colon cancer - polyps Non-neoplastic
Hyperplastic Juvenile Inflammatory
Neoplastic potential Villous adenoma Tubular adenoma Tubulovillous
adenoma
Which has the highest malignant potential?
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Colon cancer – Sporadic
Adenoma to carcinoma:
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Cancer in a polyp…
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Colon cancer - presentation Bleeding Anemia Guaiac + Obstruction Screening
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Colon cancer – pre-op evaluation
Family history! CEA Colonoscopy
Tissue for diagnosis Evaluate remainder of colon
Abdominal/Pelvic CT scan ? PET scan
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Colon cancer - staging
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Colon cancer – adjuvant therapy
Stage III 5-FU / Leucovorin based
? Stage II with adverse features Poorly differentiated LVI Obstruction/Perforation
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Colon cancer - surveillance
No survival benefit with aggressive surveillance strategies!