New Insights into Ruling Out Internal Herniations After Laparoscopic Gastric Bypass on the Abdominal CT Scan: The OPERATE study

Abstract

Background: Internal herniation (IH) is a potentially life-threatening complication after gastric bypass. Accurate diagnosis of IH remains challenging. This study aims to validate the Eindhoven2020 (EHV20) scoring system for ruling out IH and seeks to improve its diagnostic accuracy through additional radiologic parameters.

Methods: Patients participating in a prospective study on abdominal pain after gastric bypass surgery were selected if a CT scan was performed. CT scans were scored following the EHV20 scoring system containing ten signs of IH to confirm the individual and collective accuracy of these signs. Also, we evaluated the diagnostic value of additional radiologic parameters: delayed passage of contrast, dilated intestinal loops, and free fluid.

Results: A total of 375 patients with abdominal pain were included. IH was confirmed during laparoscopy in 27 patients. On CT, the highest sensitivity was achieved by the swirl sign (66.7%) and the highest specificity by a small bowel behind the superior mesenteric artery (99.7%). The area under the receiver operating characteristic curve (AUC) based on the EHV20 scoring system for ruling out IH was 0.845 (95% CI 0.730-0.959). The AUC could be improved to 0.905 (95% CI 0.825-0.985) (p = 0.088) through the incorporation of several additional signs. Overall, this new scoring system included swirl sign, small bowel obstruction, enlarged nodes, venous congestion, mesenteric edema, dilated alimentary or biliary loop, free fluid, and backward flow in the biliary loop with possible backflow in the residual stomach.

Conclusions: Incorporation of additional CT signs into an existing scoring system can help clinicians to safely rule out IH in patients with abdominal pain after bariatric surgery.

Keywords: Computed tomography; Internal herniation; Radiological signs; Standardized protocol.

Fig. 1

An example of a swirl sign and mesenteric edema in one patient from cranial to caudal, b a rotation that starts after the vena mesenteric superior from cranial to caudal which is typical for a hurricane eye sign, and c a herniated root via a surgical defect between the superior mesenteric artery and the distal mesenteric arterial branch with crowding and stretching of the mesentery from cranial to caudal which is typical for a mushroom sign

Fig. 2

Flow diagram for the patient inclusion for this study. *Excluded because of double episodes or consecutive CT scans in one episode. **Surgical findings: 1 × intussusception, 1 × necrotic cholecystitis, 1 × jejunal stenosis, 1 × gastrojejunal stenosis, 4 × adhesive small bowel obstruction, 1 × perforated gastrojejunal anastomosis perforation, 11 × no abnormalities found. IH, internal herniation

Fig. 3

Receiver operating characteristic curves for clinical signs predicting internal herniation after bariatric surgery. AUC, area under the curve; ROC, receiver operating characteristic curve

Fig. 4

Comparison of the EHV20 model and the final model