Comparative analysis of direct pancreatic function testing versus morphological assessment by endoscopic ultrasonography for the evaluation of chronic unexplained abdominal pain of presumed pancreatic origin.

Objectives: The diagnosis of "minimal change" chronic pancreatitis (MCCP) is often considered when conventional imaging studies are unrevealing in a patient population with abdominal pain of presumed pancreatic origin. Direct pancreatic function testing using secretin as a secretagogue (ST) has been considered the most sensitive method to diagnose MCCP but is not widely available to clinicians. Endoscopic ultrasound (EUS) allows detailed imaging of pancreatic architecture, but the sensitivity and specificity for MCCP remain to be determined. We sought to compare the accuracy of EUS and ST in patients with presumed MCCP.

Methods: Seventy-four patients referred to our pancreas clinic with unexplained abdominal pain and previously negative imaging studies underwent an ST for evaluation of possible MCCP. Twenty-one of these also underwent EUS. EUS images were read by 1 of 2 experts blinded to ST results.

Results: Using ST as the "gold standard," EUS had a maximum sensitivity of 71% when the cut-off for diagnosis was set at at least 3 EUS features. Conversely, maximum specificity (92%) was seen when the cut-off value was set at at least 6 EUS criteria. Diagnostic certainty was only 50% (positive predictive value = 0.5) when at least 6 criteria were used as the cut-off. MCCP was excluded with greater than 70% certainty when less than 3 criteria were present. At the best cut-off value of at least 4 features, EUS had a sensitivity of 57% and a specificity of 64%.

Conclusions: In this patient population with abdominal pain of presumed pancreatic origin, EUS and standard pancreatic function testing are often discordant. If ST is assumed to be the reference against which other tests are compared, EUS is less accurate than ST in diagnosing MCCP.