Basic Science – “Large Bowel”. Anatomy Right colon Transverse colon Left colon Descending...
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Transcript of Basic Science – “Large Bowel”. Anatomy Right colon Transverse colon Left colon Descending...
Anatomy
Right colon Transverse colon Left colon
Descending Sigmoid
Rectum What defines the
transition between the sigmoid colon and rectum?
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)
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 – 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
Crohns Disease Inflammatory condition of the GI
tract of unknown etiology Bimodal distribution “mouth to anus” Skip areas Transmural Non-caseating granulomas
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
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 – pre-op evaluation
Family history! CEA Colonoscopy
Tissue for diagnosis Evaluate remainder of colon
Abdominal/Pelvic CT scan ? PET scan
Colon cancer – adjuvant therapy
Stage III 5-FU / Leucovorin based
? Stage II with adverse features Poorly differentiated LVI Obstruction/Perforation