#2780 THE STRAIGHTFORWARD AND IMMEDIATE KIDNEY BIOPSY USING A GUIDE NEEDLE (SIGN) REDUCES THE PUNCTURE TIME AND ENABLES ADEQUATE TISSUE TO BE OBTAINED
Authors: Komatsu Hiroaki , Yamashita Tomohisa , Osanami Arata , Akazawa Chikako , Endo Kota , Tsugawa Shun , Kimura Ayumu , Miyamori Daisuke , Abe Koki , Takahashi Satoko , Gocho Yufu , Koyama Masayuki , Sato Tatsuya , Tanaka Marenao , Moniwa Norihito , Yano Toshiyuki , Ogawa Yayoi , Furuhashi Masato 
Published: June 2023

Abstract

Background and Aims
Advances in kidney biopsy procedures have improved tissue adequacy and reduced complications. Here, we report the usefulness of the Straightforward and Immediate ultrasound-guided kidney biopsy using a Guide Needle (SIGN) technique, which allows the operator to insert a biopsy gun through a guide needle placed into the fascia of the posterior abdominal wall. In this study, we retrospectively analyzed our daily practice to determine whether this technique enables nephrologists, including nephrology fellows, to shorten the procedure time and obtain more glomeruli with complication rates comparable to those of the standard ultrasound-guided kidney biopsy technique.

Methods
A single-center retrospective cross-sectional study was conducted to compare the time spent on the procedure and the number of glomeruli obtained in a group using the SIGN technique (n = 81) and a group using the standard ultrasound-guided renal biopsy technique with a needle guide (n = 143). Biopsies were performed by four board-certified nephrologists of the Japanese Society of Nephrology and four fellows. It was left to the operator to decide whether to use the standard technique or the SIGN technique. In the standard technique, an operator inserted a biopsy gun through a needle guide attached to the ultrasound probe and obtained a biopsy core from the lower pole of the kidney. In the SIGN technique, after local anesthesia, an operator inserted a 17-gauge guide needle (TSK Laboratory, Tochigi, Japan) through the needle guide without making a skin incision. The guide needle was placed in the fascia of the posterior abdominal wall. Then the operator inserted a biopsy gun through the guide needle into the lower pole of the kidney and obtained the biopsy core. The puncture time was calculated by subtracting the minute of the last puncture from the first. The number of glomeruli in the specimen for light and fluorescence microscopy was counted by kidney pathologists who did not have procedural information.

Results
The proportion of fellows using the SIGN method was significantly higher than that of specialists (56.9% and 27.7%, respectively, P&lt;0.001). The median age of subjects in the SIGN group (58 years old) was younger than that of subjects in the standard technique group (64 years old) (P = 0.009). There was no significant difference between the two groups in gender, BMI, clinical diagnosis, kidney depth, kidney volume, eGFR, or hemoglobin level. The median puncture time in the SIGN group (2 min, IQR: 1-3 min) was significantly shorter than that in the standard technique group (3 min, IQR: 2–4 min) (P &lt;0.001). The number of glomeruli obtained in the SIGN group (29 ± 15) was significantly larger than that in the standard technique group (24 ± 12) (P = 0.008). The prevalence of major complications in the SIGN group (1.2%) was similar to that in the standard technique group (2.1%) (P = 1.0). Logistic regression analysis with adjustment for age, gender, BMI, kidney depth, kidney volume, and the operator's experience showed that the use of the SIGN technique was independently associated with the puncture time ≤ 2 min (odds ratio: 5.84, 95% CI 3.0–11.4). In addition, multiple linear regression analysis with adjustment for age, gender, BMI, number of punctures, use of an 11 mm stroke biopsy gun, kidney depth, kidney volume, and operator's experience showed use of SIGN method was independently associated with a significantly larger number of glomeruli to be obtained (P = 0.015).

Conclusion
Use of the SIGN technique reduces the procedure time and enables adequate biopsy tissue to be obtained with complication rates comparable to those of the standard technique regardless of the operator's experience. Since the biopsy procedures in the current study were performed by multiple nephrologists, including fellows, the SIGN technique can be applied in a nephrology training program and can be used as the standard biopsy procedure.