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Bowel Obstruction

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Bowel Obstruction

  1. 1. Small Bowel Obstruction Liane S. Feldman, MD, FRCSC October 25, 2000
  2. 2. Small Bowel Obstruction <ul><li>One of the most common problems we face </li></ul><ul><li>Partial or complete blockage of lumen </li></ul><ul><li>Our Goal = intervene before gangrenous bowel develops </li></ul>
  3. 3. Classification of SBO Paralytic (ileus) Mechanical Partial Complete SBO
  4. 4. Causes of Mechanical SBO <ul><li>Extrinsic </li></ul><ul><li>Intrinsic </li></ul><ul><ul><li>Intraluminal </li></ul></ul><ul><ul><li>Intramural </li></ul></ul>
  5. 5. SBO: Extrinsic Causes <ul><li>Adhesions </li></ul><ul><ul><li>postop, congenital, postinflammatory </li></ul></ul><ul><li>Hernias </li></ul><ul><ul><li>external, internal </li></ul></ul><ul><li>Volvulus </li></ul><ul><li>Mass effect </li></ul><ul><ul><li>abscess, carcinomatosis, endometriosis, pseudocyst </li></ul></ul>
  6. 6. SBO: Intraluminal Causes <ul><li>Gallstone </li></ul><ul><li>Intussusception </li></ul><ul><li>Polypoid lesion </li></ul><ul><li>Bezoar </li></ul><ul><li>Enteroliths </li></ul><ul><li>Foreign body </li></ul><ul><li>Meconium ileus </li></ul><ul><li>Parasites </li></ul><ul><li>Inspissated feces </li></ul><ul><li>Inspissated barium </li></ul>
  7. 7. SBO: Intramural Causes <ul><li>Congenital </li></ul><ul><ul><li>atresia, stricture, web, duplication, Meckels </li></ul></ul><ul><li>Inflammatory </li></ul><ul><ul><li>Crohn’s, radiation, diverticulitis, postischemic stricture, meds (NSAID, KCl) </li></ul></ul><ul><li>Neoplasm </li></ul><ul><ul><li>primary, secondary </li></ul></ul><ul><li>Traumatic </li></ul>
  8. 8. Etiology of SBO <ul><li>Adhesions……..60% </li></ul><ul><li>Malignancy…….20% </li></ul><ul><li>Hernia…………….10% </li></ul><ul><li>IBD………………….5% </li></ul><ul><li>Volvulus…………..3% </li></ul><ul><li>Miscellaneous…2% </li></ul>
  9. 9. Approach to SBO <ul><li>How can we recognize SBO? </li></ul><ul><li>Is it partial or complete? </li></ul><ul><li>Is it simple or strangulated? </li></ul>
  10. 10. Recognition of SBO: History <ul><li>Previous surgery, esp. pelvic </li></ul><ul><li>Abdominal pain </li></ul><ul><ul><li>Colicky early on </li></ul></ul><ul><li>Vomiting: the more distal, the later the onset </li></ul><ul><li>Obstipation </li></ul>
  11. 11. Recognition of SBO: Exam <ul><li>Distention: Varies with level </li></ul><ul><li>Bowel sounds: may be hypoactive if late </li></ul><ul><li>R/o incarcerated groin, femoral, obturator (on rectal) hernia !!! </li></ul><ul><li>Rectal exam: masses, blood </li></ul>
  12. 12. Radiology: plain films <ul><li>Supine and upright </li></ul><ul><li>Distended loops of SB, air-fluid levels, paucity of colonic air </li></ul><ul><li>But diagnostic only 50-80% of the time </li></ul><ul><ul><li>Remember gasless abdomen with closed loop obstruction (air can’t accumulate in loop) </li></ul></ul>
  13. 13. Radiology: CT Scan <ul><li>Discriminates mechanical vs ileus </li></ul><ul><ul><li>Fluid or air-filled loops proximally </li></ul></ul><ul><ul><li>Transition zone </li></ul></ul><ul><ul><li>Collapsed bowel distally </li></ul></ul><ul><li>Can look for extrinsic causes </li></ul><ul><li>Note that obstructing ileocecal lesion can look like ileus </li></ul>
  14. 14. New modalities <ul><li>Ultrasound </li></ul><ul><ul><li>SB loop dilated > 3 cm </li></ul></ul><ul><ul><li>Dilated loop > 10 cm </li></ul></ul><ul><ul><li>Peristalsis of dilated loop </li></ul></ul><ul><ul><li>Collapsed colon </li></ul></ul><ul><li>MRI </li></ul>
  15. 15. Partial or Complete Obstruction? <ul><li>Can be diagnostic challenge </li></ul><ul><li>Important because risk of strangulation and thus initial management differs </li></ul><ul><ul><li>Partial: negligible risk of strangulation (except Richter’s), so nonoperative first </li></ul></ul><ul><ul><li>Complete: 20-40% risk of strangulation, so early operation required </li></ul></ul>
  16. 16. Partial or Complete Obstruction? <ul><li>Partial suggested by: </li></ul><ul><ul><li>Flatus 6-12 hrs after onset </li></ul></ul><ul><ul><li>Colonic air 6-12 hrs after onset </li></ul></ul><ul><li>Patients with complete obstruction may still pass gas early on due to distal peristalsis </li></ul>
  17. 17. Partial or Complete Obstruction? <ul><li>Barium test: 50 ml of barium via NG </li></ul><ul><ul><li>Clamp tube x 1 hour (unclamp if vomits, etc) </li></ul></ul><ul><ul><li>Repeat x-rays over next 12-24 hrs </li></ul></ul><ul><ul><ul><li>See if get to colon </li></ul></ul></ul><ul><ul><li>Contraindicated if suspect LBO: inspissates </li></ul></ul><ul><li>CT scan can also be useful </li></ul><ul><ul><li>Degree of distention, amount of distal air </li></ul></ul>
  18. 18. Simple vs Strangulated SBO <ul><li>Presence of strangulation increases mortality to 20% and morbidity to 40% </li></ul><ul><li>So why not just operate on the ones with strangulation? </li></ul><ul><li>Problem: we can’t diagnose strangulation on clinical grounds!!! </li></ul>
  19. 19. “ Classic” signs of strangulation? <ul><li>...Continuous pain </li></ul><ul><li>...Fever </li></ul><ul><li>...Tachycardia </li></ul><ul><li>...Peritoneal signs </li></ul><ul><li>...Leukocytosis </li></ul><ul><li>...Elevated K, amylase, alk phos, LDH, CK </li></ul><ul><li>PREDICT NECROSIS, NOT ISCHEMIA </li></ul>
  20. 20. Predicting Reversible Ischemia <ul><li>Unfortunately, reversible ischemia is not discernable clinically </li></ul><ul><li>CT: thickened bowel wall, pneumatosis, PV air, bowel wall nonenhancement </li></ul><ul><ul><li>Most are signs of necrosis not ischemia </li></ul></ul>
  21. 21. Management <ul><li>Resuscitation </li></ul><ul><li>Tube decompression </li></ul><ul><li>Timing of surgery </li></ul><ul><li>Operative strategy </li></ul><ul><li>Specific examples </li></ul>
  22. 22. Resuscitation <ul><li>All patients have intravascular depletion: </li></ul><ul><ul><li>Decreased po intake </li></ul></ul><ul><ul><li>Vomiting </li></ul></ul><ul><ul><li>Fluid sequestration </li></ul></ul><ul><li>Aggressive resuscitation with IV isotonic solution required </li></ul><ul><ul><li>Urine output, pulse guide resuscitation </li></ul></ul><ul><ul><li>CVP line in some cases </li></ul></ul>
  23. 23. Tube decompression <ul><li>NG tube: removes swallowed air and gastric fluid </li></ul><ul><ul><li>Symptomatic relief: vomiting, pain </li></ul></ul><ul><ul><li>Can give barium down tube </li></ul></ul><ul><ul><li>Prevent aspiration during induction </li></ul></ul><ul><li>Longer tubes not better than NG tubes </li></ul>
  24. 24. Timing of surgery: Partial SBO <ul><li>Usually patients suspected of adhesions from previous surgery </li></ul><ul><li>Initial nonoperative treatment for few days </li></ul><ul><ul><li>60-85% will resolve without operation </li></ul></ul><ul><li>Repeat physical exam and AXR q12 hours </li></ul><ul><li>Reassess decision to operate or not q12 hours </li></ul><ul><ul><li>Worsening status or failure to improve are indications for OR </li></ul></ul>
  25. 25. Timing of surgery: Complete SBO <ul><li>The issue </li></ul><ul><ul><li>20-40% incidence of strangulation </li></ul></ul><ul><ul><li>Cannot predict reversible ischemia clinically </li></ul></ul><ul><li>The Strategy </li></ul><ul><li>Operation after initial 12 - 24 hours of resuscitation </li></ul>
  26. 26. Operative Strategy <ul><li>May involve: </li></ul><ul><ul><li>Lysis of adhesions </li></ul></ul><ul><ul><li>Resection of obstructing lesion with anastomosis </li></ul></ul><ul><ul><li>Intestinal bypass </li></ul></ul><ul><ul><li>Rarely, stoma placement </li></ul></ul>
  27. 27. Operative Technique <ul><li>1. Clear adhesions to anterior abdominal wall </li></ul><ul><ul><li>Avoid blind finger dissection and excessive countertraction; careful, sharp dissection best </li></ul></ul><ul><li>2. Inspect region of cecum </li></ul><ul><ul><li>If distended, is this really a LBO? </li></ul></ul><ul><li>3. Work back from collapsed bowel to point of obstruction </li></ul><ul><ul><li>Don’t need to free adhesions proximal to point of obstruction </li></ul></ul>
  28. 28. Assessing viability of intestine <ul><li>Place back in abdomen with warm towel </li></ul><ul><li>Conventional clinical criteria: normal color, peristalsis, marginal arterial pulsations </li></ul><ul><ul><li>Doppler probe does not improve this impression </li></ul></ul><ul><li>IV fluorescein dye (1 amp) with Wood lamp more reliable than clinical judgement alone for borderline bowel (Bulkley, Ann Surg , 1981) </li></ul><ul><li>Rarely, second look in 24 hours </li></ul>
  29. 29. Adhesions <ul><li>Pathophysiology </li></ul><ul><ul><li>Transudated fibrinogen activated by tissue factor </li></ul></ul><ul><ul><li>Forms fibrin clot which initiates adhesion formation </li></ul></ul><ul><li>Peritoneal trauma and ischemia promote adhesion formation by release of tissue factor </li></ul>
  30. 30. Prevention of Adhesions <ul><li>Avoid serosal trauma </li></ul><ul><li>Avoid lysis of nonobstructing adhesions </li></ul><ul><li>Avoid spillage in peritoneal cavity </li></ul><ul><li>Aggressive irrigation of debris </li></ul><ul><li>Adjuvent agent: bioresorbable membrane of hyaluronic acid and carboxymethylcellulose </li></ul><ul><ul><li>Reduced adhesions to anterior abdominal wall in RCT (Becker, JACS , 1996) </li></ul></ul>
  31. 31. Incarcerated hernia <ul><li>Acutely incarcerated nonreducible hernia = early operative management </li></ul><ul><ul><li>Site of incarceration is external ring - make sure bowel does not reduce prior to direct examination </li></ul></ul><ul><li>If suspect strangulation, consider midline incision </li></ul>
  32. 32. Intraabdominal abscess <ul><li>Severe localized ileus near abscess mimics SBO </li></ul><ul><li>Drainage of abscess often sufficient to relieve SBO </li></ul><ul><ul><li>May be amenable to CT-guided drainage </li></ul></ul>
  33. 33. Malignant tumor <ul><li>Primary or secondary neoplasm with SBO - in general, treat like any other obstruction </li></ul><ul><li>History of cancer or suspected carcinomatosis- may be challenge </li></ul><ul><ul><li>Don’t assume the worst: up to 40% due to benign causes (adhesions, radiation, stricture) </li></ul></ul><ul><ul><li>Individualize treatment </li></ul></ul>
  34. 34. Radiation enteritis <ul><li>Acute enteritis (within few wks of radiation): </li></ul><ul><ul><li>Try tube decompression, steroids </li></ul></ul><ul><li>Chronic </li></ul><ul><ul><li>Laparotomy usually required </li></ul></ul><ul><ul><ul><li>Bowel looks fibrotic, gray-white, thick adhesions </li></ul></ul></ul><ul><ul><li>Local resection or bypass if resection difficult </li></ul></ul><ul><ul><ul><li>To ascending colon - outside of pelvic radiation field </li></ul></ul></ul><ul><ul><li>Avoid anastomosis of radiated bowel </li></ul></ul>
  35. 35. Acute postoperative obstruction <ul><li>Risk of obstruction 1% within 4 weeks </li></ul><ul><ul><li>Causes: adhesions (90%); internal hernia, abscess, volvulus, intussusception (10%) </li></ul></ul><ul><li>Challenge is to differentiate ileus and SBO </li></ul><ul><li>CT with oral contrast very useful </li></ul><ul><ul><li>R/o abscess </li></ul></ul><ul><ul><li>Delineate degree, site of obstruction </li></ul></ul>
  36. 36. Acute postoperative obstruction <ul><li>Management: like late obstructions </li></ul><ul><ul><li>Partial: initially nonoperative, NG decompression </li></ul></ul><ul><ul><li>Complete: early surgery </li></ul></ul><ul><li>Laparotomy required in up to 50% </li></ul><ul><li>As interval from first operation approaches 2-3 weeks, character of adhesions worsens and operation is much harder </li></ul>
  37. 37. Recurrent Obstruction <ul><li>Risk of SBO after surgery is about 5% </li></ul><ul><ul><li>Recurrence rates vary from 5-30% </li></ul></ul><ul><li>Initial nonoperative trial usually safe </li></ul><ul><ul><li>Bowel less mobile and apt to twist due to dense adhesions </li></ul></ul><ul><li>Evaluate each patient to formulate plan </li></ul><ul><li>Bowel fixation procedures largely abandoned </li></ul>
  38. 38. Role of laparoscopy in SBO <ul><li>Key is careful selection: </li></ul><ul><ul><li>(1) mild distention </li></ul></ul><ul><ul><li>(2) proximal obstruction </li></ul></ul><ul><ul><li>(3) partial obstruction </li></ul></ul><ul><ul><li>(4) “single band” anticipated </li></ul></ul><ul><li>Best chance of cure: recurrent abdominal pain in localized area with adhesions at same site </li></ul>
  39. 39. Take Home Messages <ul><li>How to diagnose SBO </li></ul><ul><ul><li>History, physical, radiology </li></ul></ul><ul><li>Classify it as partial or complete </li></ul><ul><li>Operate early in complete SBO (12-24 hrs) because we cannot diagnose strangulation clinically </li></ul>
  40. 40. Proximal or Distal?

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