Processing fine needle aspiration biopsies for electron microscopic examination. Experience implementing a procedure.

While processing needle rinses from fine needle aspiration biopsy material for electron microscopy, we experienced difficulties not fully outlined previously. Problems in preservation were traced to the time elapsed before glutaraldehyde was added to the needle rinse, which had been held in a physiologic transport medium; a tendency toward hypotonicity of the commercially prepared transport medium; and vigorous handling of the needle rinse. When these problems were dealt with, preservation improved dramatically. The problem of scanty material available for ultrastructural evaluation was dealt with by decreasing the number of smears made and filtering the needle rinse to capture tissue fragments. Implementation of the procedure required leadership, good communication, motivated cytotechnologists and cytopathologists, and continuous supervision and monitoring. In cases with adequately cellular well-preserved material available for electron microscopy, ultrastructural evaluation made a contribution of clinical value to the diagnosis in 48% of cases.