Optimal needle size for renal biopsy: in vitro and in vivo evaluation.

To evaluate the success and complication rates of small (16- and 18- gauge) needles in biopsy of the kidney, the authors performed in vitro biopsy in a cadaveric kidney and in vivo renal biopsy in 141 patients. Best results were obtained with a 16-gauge modified Menghini needle. In vitro, 9.7 +/- 5.7 (mean +/- standard deviation) glomeruli were retrieved, and the average length of tissue cores was 17.8 mm +/- 8.2. In vivo, 10.63 +/- 6.64 intact glomeruli were retrieved, and a definitive histologic diagnosis was achieved in 86% of patients. The frequency of major complications with this needle was 3.5%, and of minor complications, 5.8%. No major complications occurred after biopsy was performed with 18-gauge needles of the same design. However, the retrieval rate of glomeruli with these smaller needles was insufficient. An 18-gauge needle with two cutting edges yielded tissue cores of 11.0 mm +/- 3.5 in length. In vitro, 6.6 +/- 2.3 glomeruli were retrieved; in vivo, 9.92 +/- 6.65. A definitive histologic diagnosis was achieved with this needle in 75% of patients, and rates of 7.1% for major complications and 10.7% for minor complications were encountered.