Evaluation of kidney biopsy quality: a single-center comparative analysis of direct core microscopy-controlled and non-microscopically controlled techniques

Background and Aims
Kidney biopsy serves as an essential diagnostic modality in nephrology, particularly in the assessment of transplant recipients. The diagnostic accuracy and subsequent clinical management are highly dependent on biopsy specimen adequacy. This study provides a comparative analysis of transplant kidney biopsies performed with direct microscopic quality control, predominantly conducted by nephrologists, versus those performed without microscopic control by radiologists. The investigation focuses on key parameters including specimen adequacy, complication rates, and factors influencing biopsy outcomes.

Method
A retrospective, single-center analysis was conducted on 127 transplant kidney biopsies performed between 2023 and 2024. Data on glomeruli count, number of core biopsy samples, biopsy adequacy, complication rates (hematomas, site infections), and patient characteristics (age, gender, hypertension, diabetes, obesity, and time from transplantation to biopsy) were analyzed. An adequate biopsy was defined as one containing more than 10 glomeruli and at least 2 arteries. The Chi-squared test was employed to compare the proportions between groups for categorical variables. To compare means (along with standard deviations) for continuous variables, the Independent Samples t-test was used. Multinomial logistic regression was applied to multivariable analysis. Statistical analysis was conducted using SPSS version 29.0, with the alpha significance level 0.05.

Results
During the study period, a total of 127 kidney biopsies were performed. Among these, nephrologists conducted 38 biopsies, while 89 were performed by radiologists (T1). Nephrologists (microscopically-controlled biopsies) achieved significantly higher glomeruli counts (P = 0.01) and obtained a greater number of core biopsy samples (P < 0.001) compared to radiologists (non-microscopically controlled biopsies). Additionally, a non-significant trend suggested that nephrologists may achieve higher biopsy adequacy (P = 0.07). There were no statistically significant differences in hematoma rates or site infections between the two groups. Additionally, factors such as age, gender, hypertension, diabetes, obesity, and the time from transplantation to biopsy showed no significant differences between the nephrologists and radiologists.
In multivariate analysis after adjusting for other variables in the model (e.g., age, gender, hypertension), nephrologists are 2.48 times more likely to perform a sufficient biopsy than radiologists. However, the results are not statistically significant (P = 0.27). A longer interval between transplantation and biopsy was slightly associated with reduced odds of adequate biopsy (borderline P = 0.05).

Conclusion
Microscopy-controlled biopsies demonstrated superior biopsy adequacy regarding glomeruli count and the number of core samples obtained. However, the results did not achieve statistical significance. Despite the different number of cores obtained, no differences in complication rates were obtained between groups.