Modified plasma-thrombin method using patient-derived plasma for cell block preparation in endobronchial ultrasound-guided transbronchial fine-needle aspiration.

BACKGROUND: The plasma-thrombin method, which uses expired blood bank plasma as an ancillary component, has been widely used in cell block (CB) preparation. However, the application of expired blood bank plasma raises concerns about nucleic acid contamination. This study investigated the feasibility of using patient-derived plasma as a substitute for blood bank plasma in the modified plasma-thrombin (MPT) method for CB preparation in endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) samples. METHODS: A prospective study was conducted to compare the adequacy of CB preparation between a previously used self-clotting (SC) method and the MPT method. The EBUS-TBNA specimens from each targeted lesion were divided into paired samples: one processed using the SC method and the other using the MPT method, substituting the blood bank plasma with patient-derived plasma. RESULTS: A total of 82 paired EBUS-TBNA samples from 59 patients were analyzed. The diagnostic yield of the SC method and the MPT method was 86.6% and 97.6%, respectively. Among patients diagnosed with non-small cell lung cancer, the adequacy rate for molecular testing was 79.2% with the SC method and 91.7% with the MPT method. CONCLUSIONS: The MPT method significantly improved the cellular yield of EBUS-TBNA-derived CBs. Using patient-derived fresh plasma rather than expired blood bank plasma avoids a known contamination risk. The additional step modestly prolongs the procedure and introduces minimal risks by vein puncture. This approach is generally considered cost-effective.