Effect of suction on specimen size in fine-needle aspiration biopsy.

High incidences of unsatisfactory specimens in fine-needle aspiration biopsy for cytology have been reported previously. Inappropriate aspiration techniques may account partly for this. In this study, the effect of suction on specimen size was studied in vitro using an automatic sampler. Bovine liver, testis, and pig's kidney were used as target tissues and biopsies were performed with 18-, 20- and 22-gauge needles. Specimen weight increased rapidly and linearly with suction force (P less than .001), regardless of the target tissue or needle diameter, when standard needle movement was applied. In the absence of needle movement, the suction force, rate of increase of suction, and duration of suction had no effect on the weight of the specimens. Needle movement alone, without suction, also produced meager specimens. Suction alone does not seem to tear fragments off target tissues. Nevertheless, in combination with needle movement, suction force plays an important role in the determination of specimen size.