Su1552 PREDICTING ERCP DIFFICULT CANNULATION BASED ON CLINICAL VARIABLES, PAPILLA MORPHOLOGY AND BILIARY ANATOMY

Abstract

Difficult cannulation increases procedure duration, sedation and radiation. It is associated with increased risk of post-ERCP pancreatitis. Currently, no risk model exists for predicting difficult cannulation. Clinical variables, papilla morphology and anatomical features seen on radiological imaging maybe useful for predicting difficult ERCP cannulation. Patient demographics, laboratory results, procedural details, endoscopic papilla morphology of all ERCP performed over a 1-year period from 01/9/2018 to 31/08/2019, by a single endoscopist were recorded prospectively. The CBD-duodenum angle was measured in a CT / MRCP coronal image that demonstrated the distal bile duct, the papilla and the duodenum. The angle between the mid-point of the distal CBD, the papilla tip and the medial wall of the duodenum was measured and documented prospectively before ERCP. (Figure 1) All patients who underwent ERCPs for gallstone disease with intact papilla were included for analysis. Difficult cannulation is defined as per ESGE guidelines: cannulation duration greater than 5 minutes or greater than 5 biliary cannulation attempts or 2 inadvertent pancreatic duct cannulation. Chi square test, ANOVA, t-test and binary logistic regression were performed as appropriate to identify risk factors for difficult cannulation. Risk model internal validation was by bootstrapping. Significance of the risk prediction models were assessed by c statistic, the Brier Score and the Hosmer-Lemeshow test. A total of 169 ERCP cases were performed during the study period. Of these, 100 satisfied the study inclusion criteria. Fifty-eight patients (58%) were male. Mean age was 62+/-1.7 years. Ninety-four (94%) had successful primary cannulation. Mean cannulation time was 9.5+/-1.1 minutes. The mean CBD-duodenum angle in the difficult cannulation group was 29.5+/-11 degrees; and in the easy cannulation group, it was 24.5+/-10.9 degrees (p<0.05). A risk prediction model using bilirubin (μmol/L) (OR = 1.011; 95% confidence interval, 1.001 – 1.022 [p=0.018]), CBD diameter (mm) (OR=0.85; 95% confidence interval, 0.710-0.970 [p=0.02]), CBD duodenum angle (OR=1.069; 95% confidence interval, 1.034-1.125 [p=0.003]) and papilla subtypes (OR=2.004; 95% confidence interval, 1.305-3.575 [p=0.003]) predicted the risk of cannulation lasting longer than 5 minutes with a c-statistic of 0.79, accuracy of 72.5%, Brier score 0.185 and Hosmer-Lemeshow test p=0.82. (Table 1) Difficult cannulation can be predicted using pre-procedural laboratory values, anatomical features seen on cross sectional imaging, and endoscopic inspection of the papilla. Upon external validation, the findings of this study may enable trainers to select appropriate cases for training and for competency assessment. It will be useful in research in post ERCP pancreatitis prevention.View Large Image Figure ViewerDownload Hi-res image Download (PPT)