TEST CHARACTERISTICS OF ABDOMINAL COMPUTED TOMOGRAPHY FOR THE DIAGNOSIS OF GASTRO-GASTRIC FISTULA IN PATIENTS WITH ROUX-EN-Y GASTRIC BYPASS
Russell D. Dolan*, Ahmad Najdat Bazarbashi, Pichamol Jirapinyo, Christopher C. Thompson
Brigham & Women's Hospital, Boston, MA
Introduction:
Gastro-gastric fistula (GGF) can occur in up to 2% of patients with a history of roux-en-Y gastric bypass (RYGB). GGF can cause abdominal pain, acid reflux and contribute to weight regain. While esophagogastroduodenoscopy (EGD) and upper gastrointestinal series (UGI) are commonly used to diagnose GGF, many patients undergo computed tomography (CT) of the abdomen as an initial diagnostic modality, given its wide availability for patients presenting to the Emergency Department or in an outpatient setting. However, it is unknown how accurate CT scans are for the diagnosis of GGF, particularly in comparison to UGI and EGD. The aim of this study was to evaluate the test characteristics of abdominal CT for the diagnosis of GGF for patients with RYGB.
Methods:
We performed a retrospective chart review of patients with RYGB who underwent abdominal CT with UGI and/or EGD within the same year at our center. Baseline data was collected for age, gender, pre-RYGB weight, nadir weight, and symptoms of GG fistula including weight regain, abdominal pain and acid reflux. EGD and UGI were considered the gold standard for the diagnosis of GGF. Primary outcomes included accuracy, sensitivity, specificity, positive predictive value and negative predictive value.
Results:
A total of 236 patients were included in this analysis [183 patients with positive CT (69.6%) for GGF and 53 patients (22.5%) with negative CT]. Mean age of the cohort was 49 +/- 11.5 years, 86% were female. Mean pre-RYGB weight was 306+/- 66 lbs, and mean nadir weight was 175 +/- 45 lbs. The most common symptoms of GGF was weight regain followed by abdominal pain. Of the 183 patients with CT positive for GGF, 61 (33.3%) had undergone both EGD and UGI. Of those 183 patients with CT positive for GGF, 22.4% tested positive on both EGD and UGI, 4.4% tested positive on UG when EGD was negative, and 6.5% tested positive on EGD when UG was negative. When compared to gold standard of UGI or EGD for the diagnosis of GG Fistula, abdominal CT had a sensitivity of 81.25%, Specificity of 47.27%, PPV of 80.1% and NPV of 49.6%. The diagnostic accuracy rate was 71.86%.
Conclusions:
Abdominal CT scan has low diagnostic accuracy for gastro-gastric fistula when compared to UGI or EGD. Providers should exercise caution when interpreting results of abdominal CT in patients with suspected GGF and consider additional workup with EGD or UGI when in doubt.
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