Improved technique for performing endoscopic ultrasound guided fine needle aspiration of lymph nodes

Trans-esophageal real-time endoscopic ultrasound (EUS)-guided fine needle aspiration (FNA) has emerged as an important technique for sampling perigastrointestinal lymph nodes. The purpose of this study was to compare the yield of EUS-guided FNA of mediastinal lymph nodes using different techniques.

A 2 cm mediastinal lymph node was dissected at autopsy. FNA was performed on this lymph node with a 21 gauge needle which is used clinically for EUS-guided FNA (GIP-Mediglobe). FNA of the lymph node was performed for 60 sec, while continuous or intermittent suction was applied with a 10 ml, 20 ml and 30 ml syringe. The pathologist was blinded to the technique used for FNA of the lymph node. The slides were examined and the results recorded independently by two pathologists who were blinded to each other's findings. A similar procedure was repeated in a 2 cm lymph node removed during another autopsy.

Pathologic examination revealed metastatic transitional cell bladder carcinoma in the first lymph node, and metastatic non-small cell lung carcinoma in the second lymph node. The cellularity and quality of FNA performed with the 10 ml syringe was better than with the 20 ml or 30 ml syringe. With the 10 ml syringe, continuous suction for one minute provided a better sample than intermittent suction. FNA with a 20 ml or 30 ml syringe was more cumbersome, as it required more physical force.

Our study reveals that continuous rather than intermittent suction with smaller syringes (5-10 ml) provides optimal cellularity in EUS-guided FNA of mediastinal lymph nodes and that use of larger (20-30 ml) syringes does not improve the rate of obtaining a diagnostic specimen.