Comparison of endoscopic ultrasound and endoscopic retrograde pancreatography for the prediction of pancreatic exocrine insufficiency

Endoscopic retrograde pancreatography (ERP) is a sensitive test for the early ductal changes of chronic pancreatitis. More recently, endoscopic ultrasound (EUS) has also been proposed as a sensitive structural test for chronic pancreatitis. Few studies have compared EUS and ERP using an external reference standard. Direct pancreatic function tests (PFT) are an acceptable reference standard for chronic pancreatitis since they detect mild exocrine insufficiency. Our aim was to compare structural abnormalities as revealed by ERP and EUS for the prediction of exocrine insufficiency. Eight-three patients who underwent EUS, ERP, and secretin PFT for the evaluation of pancreatitis were identified from our database. Exocrine insufficiency was defined as a secretin PFT peak bicarbonate concentration <80 mEq/l. Based on the number of abnormal sonographic criteria observed, EUS findings were categorized as normal (<2 criteria), mild (3-5 criteria) or severe (6-9 criteria or calcifications). ERP findings were categorized based on the Cambridge classification. ERP and EUS did not differ significantly in either sensitivity (72% vs 68%, P = 0.52) or specificity (76% vs 79%, P = 0.40). ERP and EUS were similarly associated with exocrine insufficiency both in the presence of minimal (OR 3.4 and 4.9, respectively) and severe structural changes (OR 12 and 24, respectively). We consider EUS to have a diagnostic accuracy for the structural diagnosis of early- and late-stage chronic pancreatitis similar to that of ERP.