Imaging diagnosis--extrahepatic biliary tract obstruction secondary to a biliary foreign body in a cat.

An 11-year-old, neutered female British Shorthair cat was referred with a 4-week history of abdominal pain and vomiting. Abdominal ultrasonography revealed a dilated common bile duct containing a spindle-shaped structure with several reflecting interfaces. Differentials that were considered included an intraluminal foreign body, or helminth parasites within the common bile duct. Surgical exploration of the abdominal cavity demonstrated the presence of two grass awns obstructing the common bile duct. Anomalies of the portal vasculature were noted during surgery and were considered an incidental finding. The clinical signs resolved following surgical removal of the grass awns.