ADHESIVE small bowel obstruction Leslie Kobayashi Trauma Conference 2013

Overview Background Pathophysiology/Etiology Diagnosis Treatment Outcomes

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)

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

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

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

Adhesive SBO

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

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

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

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

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

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%

Diagnosis

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

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

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

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

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

Treatment

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

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

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

Treatment Peritonitis Free air? Yes OR

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

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

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

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%

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

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

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

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

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

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

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

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

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

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

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…

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

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

Are there any decision making aids?

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

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

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role Br J Surg. 2010 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

Meta-analysis of 14 prospective randomized controled studies Br J Surg. 2010 Apr;97(4):470-8. Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role Meta-analysis of 14 prospective randomized controled studies

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role Br J Surg. 2010 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

Effect of WSCA: Need for surgery

Effect of WSCA: Hospital length of stay

Water-Soluble Contrast (WSCA) – Diagnostic and Therapeutic role Br J Surg. 2010 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.

Outcomes

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

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

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

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