When to operate in SBO? Evidence-based CT criteria Brodie Parent

Patient SB 16y male c refractory UC s/p total colectomy with ileostomy (2/25/11). 3/3/11: new abdo pain, distension, pneumoperitoneum on XR. Underwent normal diagnostic laparoscopy. 3/20/11: nausea and vomiting, resolved with NG decompression. 7/22/11: repetitive emesis x4 days, only trace ostomy output, febrile to 39.4, increased abdominal pain, peritoneal irritation on exam. WBC 10.5 (34% bands)

Patient SB: clinical and radiologic mismatch 7/22/11: Abdo CT “small bowel obstruction that appears very distal, near/at the ileostomy site. No pneumatosis, free air, or bowel wall thickening. 7/23/11: normal ex-lap. Negative for any adhesive bands, strictures or creeping fat. Gradual resolution with red-rubber catheter flushes and d/c home.

When to ex-lap for SBO? Clear indications: fever, tachycardia, leukocytosis, peritonitis, portal venous gas, free air, pneumatosis, extraluminal enteric contrast, climbing lactate Traditional teaching on other CT indications: definite transition point, free intraperitoneal fluid, thickened wall, edema.

Who needs an operation in SBO? A Mayo Clinic prediction model Retrospective analysis of100 patients, each with signs/sx SBO. Each obtained abdominal CT Blinded radiologist interpreted CTs Appropriateness of surgery based on consensus of 4 surgeons’ review of operative findings and ultimate clinical course. Exclusion criteria: ascites or laparotomy/laparoscopy within 6 weeks

Mayo Study: who needs operation for SBO? Group 1 (n=48) needed operation Group II (n= 52) could be managed nonoperatively Group I had 4 patients included that were managed conservatively but were found to have ischemia and died of SBO Group II had 2 patients with nontherapeutic ex-lap

Univariate analysis Need for exploration was significantly associated with: Of note: non-significant association with ‘transition point ‘ on CT. (p=0.921) FactorP-Value (likelihood of surgery) h/o malignancy0.03 Vomiting0.02 (4.7x more likely) Free abdominal fluid<.001 (3.8x more likely) Mesenteric edema.003 Vascular engorgement.03 Absent small bowel feces sign.03 (5x less likely) Small bowel wall thickening.05

“Small bowel feces sign” Bowel wall thickening

Multivariate Predictive Model for SBO

Bottom line: Combine: 1. Vomiting; 2. Absent small bowel feces sign; 3. Free intraperitoneal fluid; 4. Mesenteric edema 21 patients had these signs. 19/21 required operation (90%). Translates to 16x greater risk for operation. Of the 21, 13 were initially nonop, but the mortality of the 13 vs. 8 was 54% vs 0%. On multivariate analysis, this combination had Specificity of 96%, Sensitivity 40%.

Confirmation: Retrospective model tested as a prospective multivariate SBO model. 100 pts with SBO, all got abdominal CT 29 pts had 4 features, 22 operated. 22/51 required operation (specificity of 86%).

On the horizon: an alternative Conservative treatment of SBO via gastrograffin in children. If >48 hrs without resolution, ml gastrograffin. If seen in cecum on abdominal XR 6h later, feeding initiated. Time until first feed and total hospital length stay was significantly shorter.

References: Bonnard A, Kohaut J, Sieurin A, Belarbi N, El Ghoneimi A. Gastrograffing for uncomplicated adhesive small bowel obstruction in children. Pediatr Surg Int (July 2011) Colon MJ, Telem DA, Wong D, Divino C. The relevnace of transition zones on computed tomography in the management of small bowel obstruction. Surgery (March 2010: 147: 373-7). Jaime Shalkow, MD; Chief Editor: Carmen Cuffari, MD. Pediatric Small-Bowel Obstruction. Pediatrics Review. W. Scott Helton, Piero M. Fisichella. ACS Surgery: Principles and Practice Chapter ch0504: Intestinal Obstruction Zielinski MD, Eiken PW, Bannon MP, Heller SF, Lohse CM, Huebner M, Sarr MG. Small Bowel Obstruction – Who Needs an Operation? A Multivariate Prediction Model. World J Surg (2010) 34: Zielinski MD, Eiken PW, Bannon MP, Heller SF, Lohse CM, Huebner M, Sarr MG., Bannon MP. Prospective, Observational Validation of a Multivariate Small-Bowel Obstruction Model to Predict the Need for Operative Intervention. American College of Surgeons :

Top adult causes of acute small bowel obstruction 1. postop adhesions 2. Malignancy (in adults) 20% 3. Hernias 10% Others: Intussusception, volvulus, crohn’s gallstone ileus

Top pediatric causes of acute bowel obstruction: #1 intussusception Others: incarcerated hernias, malrotation, postop adhesions, annular pancreas, NEC, duodenal atresia, meconium ileus, jejunal atresia

Situations necessitating emergent operation Incarcerated, strangulated hernias Peritonitis Pneumatosis cystoides intestinalis Pneumoperitoneum Suspected or proven intestinal strangulation Closed-loop obstruction Nonsigmoid colonic volvulus Sigmoid volvulus associated with toxicity or peritoneal signs Complete bowel obstruction Situations necessitating urgent operation Progressive bowel obstruction at any time after nonoperative measures are started Failure to improve with conservative therapy within 24–48 hr Early postoperative technical complications Situations in which delayed operation is usually safe Immediate postoperative obstruction Sigmoid volvulus successfully decompressed by sigmoidoscopy Acute exacerbation of Crohn disease, diverticulitis, or radiation enteritis Chronic, recurrent partial obstruction Paraduodenal hernia Gastric outlet obstruction Postoperative adhesions Resolved partial colonic obstruction