Diameter of the main pancreatic duct in chronic calcifying pancreatitis. Measurement by ultrasonography versus pancreatography.

The aim of this study was to compare the diameter of the main pancreatic duct measured by ultrasonography (US) and endoscopic pancreatography (ERCP) in cases of chronic pancreatitis and to evaluate the ability of US to gauge the dilation of the main duct accurately enough to do a side-to-side wirsungo-jejunostomy. Sixty-one measurements were recorded in 50 patients (47 men and 3 women; age: 43.7 +/- 10 years). In 11 cases, two measurements were made at an interval of more than one year. US always preceded ERCP. The measurements were compared in only 43 cases (71%), because evaluation by US was inaccurate in 14 cases (23%) and by ERCP in nine cases (15%). The mean value of the diameter measured by US was 4.30 +/- 3.01 mm, and by ERCP, 5.52 +/- 3.08 mm (mean +/- SD). When the diameter assessed by US (y) was greater than or equal to 3 mm, the diameter assessed by ERCP (x) was always greater than or equal to 4 mm. The value of x could be determined from y by the equation: x = y + 1.2 mm (r = 0.91, p less than 0.05) The difference between x and y was constant and did not depend on the size of the duct. It could be owing to the hyperechogenicity of the duct walls. We conclude that US is a reliable way to assess the dilation of the main pancreatic duct and might be an acceptable method of judging whether a side-to-side wirsungo-jejunostomy can be performed.