Safety and risk stratification of percutaneous biopsies of adult-sized renal allografts in infant and older pediatric recipients.

Background: Allograft biopsies are the gold standard for evaluating renal graft dysfunction. Adult-sized kidney (ASK) allografts are placed extraperitoneally in older children and adults and transperitoneally in infant recipients. Transperitoneal graft biopsies may be accompanied by a greater risk of bleeding and bowel injury, although no standardized pediatric study of procedure risk relating to transplant placement exists.

Methods: A retrospective single-center study of 328 consecutive ASK biopsies (277 extraperitoneal and 51 transperitoneal) performed since 1995 was conducted to stringently categorize all identified biopsy procedure complications (bleeding, transfusion requirement, bowel perforation, surgical intervention, and graft loss) relating to allograft placement, surveillance versus protocol biopsies, recipient age, and biopsy needle use, with risk stratification and recommendations for improving procedure safety. Two distinct methods of real-time ultrasound guidance were used.

Results: The overall incidence of all adverse effects was 16.1%, with perinephric hematomas accounting for 13.4% and gross hematuria accounting for 2.7%. Hematomas less than 1 cm accounted for 81.4% of all hematomas. Complications of transperitoneal biopsies (using a modified patient placement approach) paralleled those seen in extraperitoneally placed allografts (15.7% vs. 15.5%, P=0.976). Hematomas occurred more frequently (17.8% vs. 8.3%, P=0.010) in clinically indicated versus surveillance biopsies and with 16- versus 18-gauge biopsy needle use (43% vs. 13.3%, P=0.19).

Conclusion: Pediatric allograft ASK biopsies can be performed with minimal adverse outcomes. Transperitoneal ASK placement is not a contraindication for percutaneous biopsy. Strategies to improve biopsy safety include recommendations for patient positioning for transperitoneal ASKs, improved techniques for real-time ultrasound guidance, and use of finer gauge needles.