Background: Recent literature has indicated that more than 25 glomeruli need to be visualized for accurate and reproducible assessment of kidney allograft pathology.
Purpose: Concern was raised by the Kidney-Pancreas Committee of a large, urban Organ Procurement Organization (OPO) about the high variability of glomerulus yield and the increased propensity for cortical damage from wedge biopsies as compared with core biopsies. However, as of August 2006, average glomerulus yield using the needle technique failed to yield more than the suggested 25 glomeruli. The OPO instituted a process that would increase glomerulus yield while continuing to utilize the needle biopsy technique.
Methods: The OPO undertook an internal training program with its staff to improve biopsy technique, and initiated taking two cores from each kidney instead of one.
Results: With initial training in biopsy technique, glomerulus yield increased by 36% and also increased the size of the core (P < .01); however, 55% of biopsies still yielded fewer than 25 glomeruli. With an increase of biopsy core size to 14 gauge, mean glomerular yield approached 25 glomeruli per kidney, yet the majority of kidneys continued to have insufficient glomerulus yield. Over a period of 2 months, the biopsy procedure was modified to two 14-gauge cores per kidney, resulting in 91% of kidney biopsies yielding more than 25 glomeruli.
Conclusion: Our data suggest that adequate kidney allograft assessment can be obtained with two 14-gauge biopsy cores.