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Basic Science: Small Bowel

Basic Science: Small Bowel. Grace Kim, MD June 6, 2007. Basic Anatomy. 270-290 cm from pylorus to cecum Duo 20 cm Jejunum 100 cm Ileum 150 cm. Studying the SB. UGI and SB follow-through Enteroclysis CT Enteroscopy Push enteroscopy (up to 100 cm past LOT)

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Basic Science: Small Bowel

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  1. Basic Science: Small Bowel Grace Kim, MD June 6, 2007

  2. Basic Anatomy 270-290 cm from pylorus to cecum Duo 20 cm Jejunum 100 cm Ileum 150 cm

  3. Studying the SB • UGI and SB follow-through • Enteroclysis • CT • Enteroscopy • Push enteroscopy (up to 100 cm past LOT) • Double balloon enteroscopy (to TI ideally) • Capsule endoscopy (beware: obstruction)

  4. Pathology

  5. Case: 72 yo man no prior history of abdominal operations presents with nausea, vomiting, and abdominal distention x 5 days. Last BM and flatus 2 days ago. AXR as shown on next slide. • DDx? • Management?

  6. Small bowel obstruction • Etiology • Extrinsic • Adhesions (#1) • Hernias (#3) • Abscess • Mass • Intrinsic • Mass (#2) • Foreign body (bezoar, gallstone)

  7. Pathophysiology • Hyperperistalsis • Bowel dilatation • Third-spacing • Decrease in mucosal blood flow • Bacterial translocation

  8. Presentation • Crampy abdominal pain • Nausea • Vomiting • Obstipation • PE: Vitals; Abdominal exam – scars, hernias, bowel sounds, tenderness, peritonitis; Rectal exam

  9. Imaging/Labs • AXR • +/- CT scan • Chem, CBC, lactate

  10. Treatment • Suspicion for strangulation or bowel compromise • Resuscitate and operate • Simple obstruction • Conservative management (NGT decompression, resuscitate, serial exams) • Failure or decompensation • Operate • Operation: Adhesiolysis +/- bowel resection

  11. Case: During a laparotomy for a small bowel volvulus secondary to adhesions, you lyse the adhesions and detorse the small bowel. It appears congested and ischemic immediately after devolvulizing. Should this bowel be resected?

  12. Is the bowel viable? • Warm saline-soaked lap pads • Time and patience • Doppler • Fluorescein fluorescence • Planned second look

  13. Case: 70 yo woman POD#5 from an exploratory laparotomy and lysis of adhesions for SBO secondary to adhesions c/o abdominal distention. She does not tolerate advancement of diet. She has had one flatus since surgery. Labs significant for WBC 13K, K 3.2. She remains on Dilaudid IV PCA and has been minimally ambulatory. • Management?

  14. Diverticular Disease • Duodenal diverticula • Asymptomatic – no treatment • Symptomatic (biliary obstruction, hemorrhage, perforation, diverticulitis, blind loop) – choledochoduodenostomy or choledochojejunostomy vs. resection or duodenal diverticulization • Jejunoileal diverticuli • Resect if symptomatic (bleeding, perf)

  15. Meckel’s • True diverticulum • Rule of 2’s: 2% population, symptomatic in 2%, 2 years of life, 2 feet from ICV • Rx: • Bleeding: Small bowel resection • Diverticulitis: ?SBR vs. diverticulectomy • Incidental finding in child: Diverticulectomy • Incidental finding in adult: Diverticulectomy if low risk

  16. Case: You are performing a diagnostic laparoscopy for a presumed acute appendicitis in a 20 yo woman. You find thickened, inflamed ileum with extensive fat creeping. The cecum is uninvolved, and the appendix is normal. • Diagnosis and management?

  17. Crohn’s Disease • Can involve GI tract from mouth to anus • 40% ileocolic, 30% SB only, 30% colon or anorectum only • Transmural inflammation, non-caseating granuloma formation • Skip lesions • Usually spares rectum • Medical and surgical treatment is palliative

  18. 3-7/100,000 • Highest incidence in N. America and Europe • Bimodal distribution (20-30s and 60s) • Etiology unclear • Increased risk of developing SB adenocarcinoma (100x)

  19. Presentation • Relapsing/remitting abdominal pain and diarrhea with weight loss • Extra-intestinal manifestations (30%) • Skin lesions (erythema nodosum and pyoderma gangrenosum) • Arthritis and arthralgias • Uveitis and iritis • Hepatitis and pericholangitis • Aphthous stomatitis

  20. Diagnosis • Barium study of small bowel (linear ulcers, transverse sinuses, and clefts) • Endoscopy (discrete ulcers,cobblestoning, skip lesions • Adjunctive labs: ASCA positive/pANCA negative

  21. Medical Management • Aminosalicylates (Pentasa, Asacol) • Antibiotics (Flagyl, cipro) • Corticosteroids • Immunosuppresive drugs (6-MP, aza) • Anti-TNFα (Infliximab)

  22. Surgery • Reserved for complications and failures of medical management (75%) • Indications • 1 – Obstruction • 2 – Fistula • 3 – Perforation/Abscess • 4 – Perianal disease • 5 – Toxic megacolon

  23. “Operative treatment of a complication should be limited to that segment of bowel involved with the complication and no attempt should be made to resect more bowel even though grossly evident disease may be apparent.”

  24. Surgical options • Small bowel resection • Ileocolic resection • Strictureplasty • Take mucosal bx first

  25. Small Bowel Tumors

  26. Represent 2% of all GI malignancies • Presentation: intermittent or partial SBO, bleeding, pain, perforation, weight loss • Malignant lesions usually will cause sx – based on tumor infiltration • Benign lesions may/may not cause sx – based on intussusception • Dx: SBFT, enteroclysis, CT, enteroscopy

  27. Benign Lesions • Adenomas • Lipomas • Hemangiomas • Hamartoma • Usually asymptomatic • Should be excised or resected

  28. Malignant Tumors • Metastatic Disease (cervix, ovaries, renal, stomach, colon pancreas, melanoma) • Adenocarcinoma • Carcinoids • Malignant GIST • Lymphoma

  29. Adenocarcinoma • 50% SB tumors • More frequently proximal SB • Treatment: Wide resection with 10-cm margins, ?adjuvant • Prognosis poor – usually late stage when diagnosed

  30. Carcinoids • From Kulchitsky cells – enterochromaffin cells • Produce 5-HIAA, chromogranins, neuropeptide K, substance P • 80% found within 2’ of TI • AIR: Appendix (45%), Ileum (28%), Rectum (16%) • 10% have carcinoid syndrome (diarrhea, blushing, bronchospasm, hypotension, endocardial fibrosis – R heart failure) • Metastatic carcinoid or tumors that bypass the portal system • Fibrotic, desmoplastic reaction in mesentery

  31. Dx: high index of suspicion, urine 5-HIAA, CT (mesenteric shortening), SBFT, octreotide scan

  32. Case: You are operating on a 70 yo woman with a SBO presumably from a carcinoid tumor. During induction of general anesthesia, she develops SVT, hypotension, and elevated peak airway pressures. • Management?

  33. Carcinoids • Treatment: Segmental resection • Beware: Carcinoid crisis with general anesthesia (Rx: somatostatin, hydrocortisone, antihistamine) • prep all patient with preoperative octreotide • Adjuvant: doxo, 5-FU, streptozocin, chemoembolization bulky liver disease • Palliative for carcinoid syndrome: octreotide • Experimental: radionuclide somatostatin agonists “smart bomb”

  34. Last two… • Lymphoma • Ileum • Risk factors: immunodeficiency, celiac disease • Rx: Wide resection with nodes • GIST • Jejunum/ileum • Segmental resection

  35. Vascular

  36. Acute Mesenteric Ischemia • Acute-onset pain, out of proportion to exam, fever, Heme (+) stool • MI, A-fib, mural thrombus, mitral valve disease • Dx: CT scan (good for bowel, large vessels), angiogram, MRA

  37. Embolus Acute onset without antecedent sx Lodge distal to middle colic and jejunal branches of SMA Sparing of proximal jejunum and R colon Thrombus Antecedent intestinal angina Origin of vessel Entire SB and R colon affected

  38. Nonocclusive Mesenteric Ischemia (NOMI) • Optimize fluid resuscitation • Improve CO • Eliminate vasopressors • Selective vasodilatory injection (papaverine) • Bowel resection for frankly necrotic bowel

  39. Mesenteric Embolic Disease • Surgical embolectomy • Exposure of SMA • Transverse or longitudinal arteriotomy (vein patch) • 3 and 4-Fr Fogarty embolectomy

  40. Acute Mesenteric Thrombotic Disease • Bypass • Antegrade or retrograde • Conduit: autologous greater saphenous vein (acute situation) • Inflow: supraceliac aorta, infrarenal aorta, iliac artery

  41. Outcome • Perioperative mortality 62% • MODS, ischemia/reperfusion insult • Long-term TPN 31%

  42. Chronic Mesenteric Ischemia • Chronic post-prandial abdominal pain in a vasculopath • Dx: Duplex, angiogram

  43. Management • Visceral Bypass • One or two-vessel bypass • Inflow: supraceliac, infrarenal • Conduit: Vein or PTFE/Dacron • Endovascular • PTA • *not many studies supporting management

  44. Outcome • Mortality 8%, morbidity 30% (includes acute) • Primary patency 89% at 72 months • 5-yr survival 64%, 3-yr symptom-free rate 81% • Endovascular approaches promising – more recent studies: similar symptom-free rate with lower morbidity and mortality

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