When size matters: diagnostic value of kidney biopsy according to the gauge of the biopsy needle.

Background: Kidney biopsy is a vital tool in the diagnosis of kidney disease. Although it has become a routine procedure, it is not complication-free. Some serious complications of percutaneous kidney biopsy include retroperitoneal hemorrhage and death. There is an increased belief that smaller biopsy needle size results in a lower complication rate. As renal pathologists, we witness an increased number of kidney biopsies performed with a small needle size (as low as gauge 22), which results in inadequate tissue sampling and often non-diagnostic biopsy results. Herein we report the diagnostic value of kidney biopsies according to the size of the biopsy needles.

Methods: We performed kidney biopsies from nephrectomy specimens using biopsy needles of different sizes. Morphologic parameters were analyzed.

Results: We found that biopsies performed by small needles (gauges 20 and 22) contain significantly lower numbers of glomeruli and blood vessels, which limits pathologic evaluation. Data from our institution do not show differences in kidney biopsy complication rates between 16- and 18-gauge needles.

Conclusions: Our data indicate that small biopsy needles do not provide sufficient material for diagnosis, and they increase the likelihood for a repeat biopsy.