A prospective randomized trial of three different sizes of core-cutting needle for renal transplant biopsy

Background. Needle-core biopsy remains one of the most important investigations in cases of renal allograft dysfunction. The size and quality of the biopsy material are likely to be important factors in achieving an accurate diagnosis. The aim of this study was to compare the success and complication rates of renal transplant biopsy procedures using three differently sized needles. Methods. One hundred renal allograft recipients undergoing transplant biopsy using an automated needle core method were randomized to a 14, 16, or 18 gauge (G) needle. The size of each biopsy core was measured, and the presence or absence of renal cortical and medullary tissue and the number of glomeruli were recorded. Assessments of the ease with which the procedure was performed, the diagnostic usefulness of the biopsy material, and the discomfort associated with the procedure were made using verbal response and linear analog scales. Results. Fourteen G biopsy cores (N = 33) were larger than both 16G (N = 33) and 18G (N = 34) cores and contained more gomeruli (mean number for 14G, 16G, and 18G = 15, 11 and 9, respectively). There were no differences in the ease of use of the three needle types, but scores for diagnostic usefulness were higher for 14G versus 18G and 16G versus 18G. The 14G needle was associated with significantly more pain than the two smaller needles when this was assessed using a linear analog score. Macroscopic hematuria occurred in eight patients, but there were no differences in complications rates between the three groups. Conclusions. All three needle sizes are safe for use in renal allograft biopsy using a semiautomated biopsy gun. The larger needles provide more tissue and glomeruli and, thus, are more diagnostically useful. Use of a 14G needle may be associated with more pain, and the 16G needle appears to offer the best compromise between diagnostic usefulness and patient acceptability.