EUS is the best diagnostic tool. Also, MRI and CT scan of pancreas. Also bloodwork for pancreatic enzymes, amylase and lipase. If just one of these suggest pancreatitis, doctors will continue with the testing. I had it all, and they all suggested pancreatitis. Reason for the stool test was because I was having so many stools a day, not necessarily diarrhea. Doc tested me for parasites, Ulcerative Colitis, Crohns, and pancreatic enzymes because I was losing so much weight and had so many stools.