Capillary versus aspiration biopsy: Effect of needle size and length on the cytopathological specimen quality

Purpose To test the value of the nonaspiration, or capillary, biopsy technique by experimental comparison with the conventional fine-needle aspiration technique using various needle gauges and lengths. Methods On fresh hepatic and renal tissue from five autopsies, multiple biopsy specimens were taken with 20, 22, and 23-gauge Chiba needles of 5, 10, 15, and 20-cm length, using the aspiration technique and the capillary technique. The resultant specimens were graded on the basis of a grading scheme by a cytopathologist who was blinded to the biopsy technique. Results The capillary technique obtained less background blood or clot which could obscure diagnostic tissue, although not significantly different from the aspiration technique (p=0.2). However, for the amount of cellular material obtained, retention of appropriate architecture, and mean score, the capillary technique performed statistically worse than aspiration biopsy (p<0.01). In addition, with decreasing needle caliber (increasing needle gauge) and increasing length, the capillary biopsy was inferior to the aspiration biopsy. Conclusion The capillary biopsy technique is inferior to the aspiration technique according to our study. When the capillary technique is to be applied, preference should be given to larger caliber, shorter needles.