Ampulla of Vater morphology has been reported to impact cannulation and complication rates during ERCP. However, there are several morphology classification systems and results in literature are not unanimous. We aimed to test the above hypothesis using data from the Greek ERCP registry.

We conducted a multicenter observational study with prospectively collected data from the Greek national ERCP database. Ampulla morphology was classified according to the Haraldsson classification (United European Gastroenterology Journal, 2017). The registry was searched for ERCP cases performed in Jan 2023 - Sept 2025, in patients with naïve ampulla of Vater. We performed univariate and multivariate analyses.

A total of 1675 ERCP cases in patients with naïve ampulla of Vater and available data from 6 centers regarding ampulla morphology were included (mean age 73 years (SD 15); 69% with bile duct stones, jaundice 63%, cholangitis/sepsis 16%, biliary stricture 12%). The most frequently described type of ampulla was type 1 (n=928, 55.4%), followed by type 2 (n=395, 23.6%), type 3 (n=287,17.1%) and type 4 (n=65,3.9) %). Overall,  51.4% of the cases were performed electively, most patients (42,4%) had an ASA score of 2 (, 27.9% score 1, 25.6% score 3, 3.8% score 4, and 0.2% score 5) and underwent ERCP under conscious sedation (82.9% followed by 16.4% deep sedation ,and 0.7% general anesthesia). The deep bile duct cannulation success rate was 94.3% and it was related to ampulla of Vater morphology (p=0.04) with type 2 and 4 showing higher failure rates compared with type 1 (p=0.02 and p=0.01 respectively). The overall complication rate was 11.7%, with no significant difference among the four ampulla morphology types (p=0.2). Post ERCP pancreatitis occurred in 6.6% and cholangitis in 5.8% but did not differ significantly among ampulla morphology types (p>0.05), Perforation occurred in 4 patients and was only observed in type 2 ampullas.  In multivariate analysis ampulla morphology types 2 and 4 were independent predictive factors of cannulation failure (p=0.001; OR 2.0, 95% CI 1.3-3.0).

Ampulla morphology type 2 and 4 appear to be associated with cannulation failure and possibly complications. These findings may have implications in daily clinical practice, especially in the field of ERCP training.