On-site determination of cytologic adequacy increases the accuracy of EUS-guided FNA (EUS-FNA); however, on-site cytotechnologists are not available to all endosonographers. We hypothesize that experienced endosonographers can accurately assess whether an on-site FNA specimen is adequate.

To determine the accuracy of on-site cytopathology interpretation of EUS-FNA specimens by comparing endosonographers with a cytotechnologist.

Prospective double-blind controlled trial.

Academic medical center with a high-volume EUS practice.

Consecutive patients undergoing EUS-FNA of lymph nodes or pancreas tumors.

Accuracy, sensitivity, and specificity of 3 endosonographers and 1 cytotechnologist for interpretation of cytologic specimen adequacy and diagnosis compared with a criterion standard of a board-certified cytopathologist.

There were 59 lymph node, 49 pancreas, and 9 liver specimens (117 total). For determination of adequacy, none of the endosonographers were statistically equivalent to the cytotechnologist (P = .004). For determination of suspicious/malignant versus benign specimens, all 3 endosonographers were inferior (P < .001) to the cytotechnologist.

This study represents a small group of trained endosonographers in a high-volume practice and may not be applicable to other settings. The sample size does not allow an accurate evaluation of different biopsy sites (eg, pancreas vs lymph node).

Even trained endosonographers have variable and, in some cases, inferior abilities to interpret on-site cytologic adequacy compared with cytotechnologists.