Sydney George Chapman, 75, was pronounced dead at Winchester hospital on June 22, an inquest heard.
He had been recovering after undergoing an ERCP in Basingstoke six days before.
This left Mr Chapman with pancreatitis – despite there only being a 5 per cent risk of the procedure causing this.
Dr Michael Reynolds who performed the ERCP on Mr Chapman told Winchester Coroner's Court: "Mr Chapman had a difficult diagnosis. He was seen in Winchester in February after reporting abdominal pain.
"He had scans which showed the drainage system of the liver but it wasn't clear what was going on, so we decided to do the ERCP.