The accuracy of ERCP-based brush cytology or forceps biopsy for tissue diagnosis is relatively low and usually does not exceed 70%.
By contrast, reported accuracy rates for EUS-guided FNA of pancreatobiliary masses are over 80%.
Researchers in Germany carried out a prospective study to compare these two modalities for the first time in the diagnosis of indeterminate biliary strictures and pancreatic tumors.
The study included 50 consecutive patients (29 men, 21 women; mean age 62.1 years) with obstructive jaundice in whom a tissue diagnosis was required.
During ERCP, intraductal specimens were obtained with a forceps and with two different types of brush (conventional and spiral suction) in random order.
For biliary strictures, combined ERCP- and EUS-guided tissue acquisition seems to be the best approach
During EUS, only visible mass lesions or localized bile duct wall thickening were aspirated (22-gauge needle), with at least two passes yielding material sufficient for assessment.
A cytopathologist was not present in the procedure room to evaluate specimen adequacy.
The reference methods used by the group were surgery, other biopsy results, follow-up until death, or the conclusion of the study (mean follow-up 20 months).
The final diagnoses were malignancy, 28 (16 pancreatic, 12 biliary), and benign biliary stricture, 22.
The research group found that the sensitivity and specificity for ERCP-guided biopsy were 36% and 100%, respectively; for ERCP-guided cytology (when using conventional and spiral suction brushes), 46% and 100%, respectively; and for EUS-guided FNA, 43% and 100%, respectively.
The researchers noted that if the punctured lesions were considered (n=28) alone, the sensitivity of EUS-guided FNA was 75%.
In general, the group found that sensitivity was better for ERCP-based techniques in the subgroup biliary tumor (ERCP 75% vs. EUS 25%), whereas EUS-guided biopsy was superior for pancreatic mass (EUS 60% vs. ERCP 38%).
Dr Rosch, one of the co-authors of the report concluded that, "For biliary strictures, combined ERCP- and EUS-guided tissue acquisition seems to be the best approach to tissue diagnosis."
He added that "From a clinical standpoint, it appears reasonable, when a tissue diagnosis is required, to start with ERCP if biliary malignancy is suspected and with EUS when a pancreatic tumor is thought to be the cause of a biliary stricture."