Is bigger better? A retrospective analysis of native renal biopsies with 16 Gaugeversus18 Gauge automatic needles

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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.


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.


A total of 934 native-kidney biopsies were performed with real time ultrasound guidance: 753 with Bard Max Core 16G × 16 cm needles, and 181 with Bard Magnum 18G × 20 cm needles. The median (range) of total glomeruli count per biopsy was higher in the 16G group compared with the 18G group (19 (0–66)vs12 (0–35),P< 0.001), despite having fewer cores per biopsy (2 (0–4)vs3 (1–4),P< 0.001). The 16G group provided a greater proportion of adequate biopsy samples (94.7%vs89.4%,P= 0.001). There was no significant difference in the frequency of total complications between the 16G and 18G groups (3.7%vs2.2%,P= 0.49).


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.


This is an important practical issue – the appropriate gauge of biopsy needles. This study is large and aims to answer the core question – 16G or 18G.

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