Percutaneous Renal Biopsy Using an 18-Gauge Automated Needle Is Not Optimal

Background: As percutaneous renal biopsies (PRBs) are increasingly performed by radiologists, an increase in the use of 18-gauge automated needle stands to compromise adequacy. We compare the adequacy and safety of PRB with 14-, 16-, and 18-gauge automated needles.

Methods: PRB of native (N-592) and transplant (T-1,023) kidneys was performed from January 2002 to December 2019 using real-time ultrasound. Baseline clinical and laboratory data, biopsy data (number of cores, total glomeruli, and total glomeruli per core), and outcome (hematoma on renal US at 1-h, complications, and transfusion) were collected prospectively. PRB with N14g (337) versus N16g (255) and T16g (892) versus T18g (131) needles were compared. A p value of <0.05 was significant.

Results: PRB with an 18-g needle yielded the lowest number of total glomeruli per biopsy (N14g vs. N16g: 33 ± 13 vs. 29 ± 12, p < 0.01 and T16g vs. T18g: 34 ± 16 vs. 21 ± 11, p < 0.0001), significantly fewer total glomeruli per core (T16g vs. T18g: 12.7 ± 6.4 vs. 9.6 ± 5.0, p < 0.001 and N16g vs. T18g: 14.2 ± 6.3 vs. 9.6 ± 5.0, p < 0.001). A hematoma by renal US 1-h post-PRB was similar for native (14g-35% vs. 16g-29%, p = 0.2), and transplant biopsies (16g-10% vs. 18g-9%, p = 0.9) and the complication rate for native (14g-8.9% vs. 16g-7.1%, p = 0.5), transplant biopsies (16g-4.6% vs. 18g-1.5%, p = 0.2) and transfusion rate for native (14g-7.7% vs. 16g-5.8%, p = 0.4), and transplant biopsies (16g-3.8% vs. 18g-0.8%, p = 0.1) were similar irrespective of needle size.

Conclusions: PRB of native and transplant kidneys with the use of a 16-gauge needle provides an optimal sample. However, our experience in transplant biopsies suggests the use of an 18-gauge needle stands to jeopardize the diagnostic accuracy of the PRB while not improving safety.