Is bigger better? A retrospective analysis of native renal biopsies with 16 Gauge versus 18 Gauge automatic needles

Aim Percutaneous renal biopsy (PRB) remains the gold standard for the diagnosis of renal disease; however, the tissue yield which relates to the optimal needle size used for native-kidney biopsies has not been clearly established. Our study compares the sample adequacy and complication rates using 16 gauge (G) and 18 gauge (G) automatic needles on native kidney PRB. Methods A retrospective analysis was performed of native-kidney biopsies at two centres, one exclusively using 16G and the other exclusively using 18G needles. All samples were assessed by a single centralized pathology service. We compared patient characteristics, indications, diagnoses, adequacy of tissue samples, and complications. Results A total of 934 native-kidney biopsies were performed with real time ultrasound guidance: 753 with Bard Max Core 16Gx16cm needles, and 181 with Bard Magnum 18Gx20cm needles. The median (range) of total glomeruli count per biopsy was higher in the 16G group compared with the 18G group (19 (0-66) vs 12 (0-35), P<0.001), despite having fewer cores per biopsy (2 (0-4) vs 3 (1-4), P<0.001). The 16G group provided a greater proportion of adequate biopsy samples (94.7% vs 89.4%, P=0.001). There was no significant difference in the frequency of total complications between the 16G and 18G groups (3.7% vs 2.2%, P=0.49). Conclusion This retrospective study demonstrates 16G needles provide more glomeruli, more diagnostically adequate renal tissue, with fewer cores without a significant increase in complications compared with 18G needles. Based on these observations, 16G needles should be considered as the first line option in native-kidney PRB.