Milwaukee classification of biliary sphincter of Oddi dysfunction4 5
| Type I | Type II | Type III |
| Biliary pain plus: | Biliary pain plus 1 or 2 of: | Biliary pain alone |
| • Delayed drainage of the common bile duct (> 45 minutes) | • Delayed drainage of the common bile duct (> 45 minutes) | |
| • Dilated common bile duct (> 12 mm on ultrasound) | • Dilated common bile duct (> 12 mm on ultrasound) | |
| • Elevated aminotransferase, alkaline phosphatase or bilirubin (> 2×normal on 2 occasions) | • Elevated aminotransferase, alkaline phosphatase or bilirubin (> 2×normal on 2 occasions) |