1. ADHESIVE small bowel obstruction
Leslie Kobayashi
Trauma Conference 2013

2. Overview Background Pathophysiology/Etiology Diagnosis Treatment
Outcomes

3. Small bowel obstruction (SBO)
Mechanical obstruction of the small bowel preventing free passage of intraluminal material
May be due to:
Bowel wall inflammation, edema or tumor
Intraluminal obstruction (bezoar, gallstone, foreign body)
Extrinsic compression (adhesion, hernia, tumor, volvulus)

4. Background
Obstruction is the most common small bowel pathology requiring surgical consultation
Accounts for 20% of acute surgical admissions
Costs $800 million annually

5. Most common causes of SBO
Background
Most common causes of SBO
Adhesive 60-75%
Malignancies 9-11%
Hernias 8-18%
IBD 5%

6. SBO in the virgin abdomen
Historically
Primary causes: hernia and volvulus
Currently
Primary causes: malignancy, IBD
All cases of SBO in a virgin abdomen should be taken for operative exploration due to high failure rate of NOM and concern for malignancy

7. Adhesive SBO

8. Capillaries & Migration of Fibroblasts
Pathophysiology
Adhesions are fibrous bands of connective tissue that form in response to trauma, surgical manipulation, or inflammation
Capillaries & Migration of Fibroblasts
Peritoneal Damage
Bleeding
Inflammation
Stable Fibrin matrix
Fibrinogen
Adhesion
Barmparas et al, J Gastrointest Surg 2010

9. Pathophysiology Postmortem study
Minor procedure: 51% had adhesions
Major procedure: 72% had adhesions
Multiple operations: 93% had adhesions
93% of 210 patients with abdominal procedures, had intra-abdominal adhesions at re-laparotomy.
Weibel MA. Am J Surg 1973
Menzies D. Ann R Coll Surg Engl 1990

10. Risk factors for SBO Age Comorbid conditions Prior surgery
Stepwise increase with number of prior procedures
Surgical technique
Open technique associated with significantly higher rates of SBO
Risk increased 2-8x’s

11. Procedure related risk
Surgery
Technique
Total # of patients
Adhesion-related readmission
Appendectomy
Open
Lap.
266,695
4,445
1.4%
1.3%
Cholecystectomy
141
7,103
7.1%
0.2%
Colectomy
121,058
930
9.5%
4.3%
Ileal pouch-anal anastomosis
5,268
19.3%
Laparotomy for Trauma
1,913
2.5%
Gynecological procedures
24,998
773
17.1% 0%
Barmparas et al, J Gastrointest Surg 2010

12. Trends over time? No ↓risk of SBO with laparoscopy compared to open
Laparoscopy rate ↑over time
Has this resulted in ↓rate of SBO? No
Scott, et al Am J Surg 2012 and Angenete, et al Arch Surg 2012

13. Overall incidence of SBO 4.6% Top operations leading to SBO
Etiology
Overall incidence of SBO 4.6%
Top operations leading to SBO
Appendectomy 14-30%
Colorectal 21-34%
Gynecological surgery 12-28%

14. Diagnosis

15. Diagnosis: Clinical presentation
Anorexia, nausea, vomiting, obstipation (90%), constipation (80%), abdominal pain
Abdominal distension, high pitched bowel sounds, tympany, TTP, feculant NGT output/vomitus
Hypocholoremic, hypokalemic metabolic alkalosis

16. Diagnosis: Radiology findings
Plain films
Benefits: rapid, repeatable, no contrast required, patient does not have to be supine for prolonged time period, can be done at bedside

17. Diagnosis: Radiology findings
Distended loops of bowel
Air-fluid levels
Step laddering of bowel
Lack of air in colon, rectum

18. Diagnosis: Radiology findings
CT scans
Benefits: high sensitivity and specificity (90%), gives information on intra and extraluminal pathology, highly sensitive for free air/fluid, can identify transition zones, hernias, and bowel ischemia

19. Diagnosis: Radiology findings
Dilated bowel
Transition zone from dilated to collapsed
Passage of contrast material (partial) or not (complete)
Bezoars, masses

20. Treatment

21. Treatment Initial management of all patients should include:
NGT decompression
Judicious fluid resuscitation
Correction of electrolyte imbalances
Foley catheter and close monitoring or UOP
+/- central venous and/or arterial catheters

22. Treatment
Majority of cases (60-82%) can be treated conservatively with non- operative management (NOM)
Three indications for Early Operative Management (EOM):

23. 1: Perforation
Any patient with peritonitis or free air-indicating perforation should go straight to OR

24. Treatment
Peritonitis
Free air?
Yes OR

25. 2: Ischemia
Any patients with concerning signs/symptoms for gangrenous or ischemic bowel should also go to the OR ASAP

26. Signs of bowel ischemia
Clinical: sensitivity 40-50%
Hypotension
Tachycardia
Fever or leukocytosis,
Lactic acidosis
SIRS response
Deterioration in exam

27. Physical signs Strangulated (N=21) Sensitivity Specificity PPV
1983
Physical signs
Strangulated
(N=21)
Sensitivity
Specificity
PPV
Temp (°F)
99 ± 0.9 24 70 36
Pulse
104 ± 23 52 43 39
No bowel sounds
5/20 25 83 50
Peritonitis
6/21 29 97 86

28. 2004
Clinical symptoms, base deficit, leukocytosis, blood glucose, and SIRS were assessed
→SIRS and base deficit were independently associated with gangrenous bowel
Sensitivity: 92%, Specificity: 96%
PPV: 92%, NPV: 96%

29. Signs of bowel ischemia
Plain films
Bowel wall edema, portal venous gas
CT: sensitivity 85-90%
Thickened bowel wall, target sign, mesenteric stranding, congestion, ascites, pneumatosis, portal venous gas, decreased bowel wall enhancement

30. Treatment No Yes Yes OR OR Peritonitis Free air? Ischemia?
Fever, Tachycardia, Acidosis
Portal air, pneumatosis, ascites mesenteric stranding
Yes OR

31. 3: High grade, or closed loop SBO
Patients with high grade SBO, or those with closed loop obstruction should be strongly considered for early operative management

32. Air-fluid levels of differential height
Signs of high grade SBO
> 25mm
Air-fluid levels of differential height
in the same loop
Air fluid width of
25 mm or more

33. Accuracy of plain X-ray to diagnose a high grade SBO
Sensitivity 66-75%
Results of this technique are:
Equivocal in about 20%–30%
Normal, nonspecific, or misleading in 10%–20%
Maglinte AJ, AJR Am J Roentgenol 1997

34. Signs of high grade SBO Sensitivity 80-93%
Contrast does not pass transition zone
Colon with little gas or fluid
Fecalization of small bowel

35. Diagnosis: Radiology findings
EAST Guidelines 2012
Level 1 recommendation for CT scans in SBO as they can provide incremental increase in information compared to plain films in differentiating grade, severity and etiology that may lead to changes in management

36. Treatment Yes OR No Peritonitis Free air? No Ischemia?
Fever, Tachycardia, Acidosis
Portal air, pneumatosis, ascites mesenteric stranding No
Closed loop or high grade SBO?
Yes-OR

37. Summary: treatment Three indications for early operative management:
Perforation
Ischemia
Closed loop or high grade obstruction
All others can be considered for NOM

38. Treatment Yes OR No Peritonitis Free air? No Ischemia?
Fever, Tachycardia, Acidosis
Portal air, pneumatosis, ascites mesenteric stranding No
Closed loop or high grade SBO?
Yes-OR
No-obs

39. Principles of NOM Bowel rest, NGT decompression, fluid resuscitation
Serial abdominal exams and blood tests, consider serial abdominal films
Explore if deterioration in clinical exam, or new e/o ischemia or perforation
Keep in mind…

40. NOM Delay to OR is associated with: Longer LOS
Increased incidence of bowel necrosis and need for bowel resection
Increased mortality
Increased morbidity

41. Given risks of delay to surgery:
NOM
Given risks of delay to surgery:
How long should NOM trial last?
Studies suggest 48hrs although can be longer in pSBO
NIS data suggest delay of ≥4d associated with 64% increase in mortality and increased LOS
Schraufnagel et al, J Trauma 2013

42. Are there any decision making aids?

43. NOM EAST Guidelines 2012 Level 2 recommendation
Consider water soluble contrast administration for prognosis and/or treatment in patients who fail to improve within 48hrs

44. Water soluble contrast
Hyperosmolar radiopaque agent
Potential aid in prognosis
Passage of contrast into LB may predict successful NOM
Failure of progression predicts need for OR
Theoretically decreases bowel wall edema and may promote resolution of SBO

45. Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
Br J Surg Apr;97(4):470-8.
Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
50–100ml Gastrografin or 40ml Urografin administered orally
Abdominal plain radiographs after 4 h, 8 h or 24 h to follow contrast through the GI-tract

46. Meta-analysis of 14 prospective randomized controled studies
Br J Surg Apr;97(4):470-8.
Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
Meta-analysis of 14 prospective randomized controled studies

47. Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
Br J Surg Apr;97(4):470-8.
Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
If the contrast reaches the colon within 4–24 h, obstruction will resolve without operation in 99% of patients.
Timing n
Sensitivity
Specificity
PPV
NPV
4-8h
312 95 99
100 85
24h
196 97

48. Effect of WSCA: Need for surgery

49. Effect of WSCA: Hospital length of stay

50. Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
Br J Surg Apr;97(4):470-8.
Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role
Conclusion
Water-soluble contrast was effective in predicting the need for surgery in adhesive SBO (sensitivity 96%, specificity 98%)
In addition, it reduced the need for operation and shortened hospital stay.

51. Outcomes

52. Outcomes Mortality 3-8% Rates of recurrence 15-20% over 5 years
Rate of recurrence, # of recurrences, and time to recurrence significantly better in Operatively Managed compared to NOM group

53. Outcomes California OSHPD database
32,583 patients admitted in 1997 with SBO
76% NOM
24% OM
OM group associated with
Decreased mortality, decreased rate of readmissions, fewer readmissions, and longer time to readmission
Foster, et al JACS 2006

54. Summary Adhesions account for the majority of SBO in the US
Clinical exam and xrays reliably diagnose SBO
Early OM should be undertaken in patients with perforation, ischemia, and high grade or closed loop SBO

55. Summary: When to operate?
NOM successful in majority of patients, but shouldn‘t exceed 4d
Consider use of Water-soluble contrast agents for both diagnostic and therapeutic purposes
Operative management can decrease the rate and number of recurrences, and prolong the time to recurrence