The Tangential Extraperitoneal Retrorenal Approach in Kidney Transplant Biopsy: An Observational Study to Assess Complication and Adequacy Rates

Introduction: Ultrasound-guided percutaneous kidney allograft biopsy is the gold-standard for pathology work-up. Recent studies postulate better safety and efficacy for tangential approaches, however, there is no recommendation regarding biopsy needle path. In this context, we previously described the unified tangential extraperitoneal retrorenal (TER) approach for standard allograft biopsy.Methods: A single-center retrospective observational study evaluated safety and efficacy of the TER biopsy approach among 250 patients that underwent 330 ultrasound-guided kidney transplant biopsies between January 2011 and May 2020.Results: The overall major complication rate was 0.56% per biopsy attempt (1.21% per biopsy) including blood transfusion, arterial embolization and bladder catheterization for gross hematuria in 0.28, 0.14 and 0.14% of biopsy attempts, respectively (0.61, 0.30 and 0.30% of biopsies, respectively). Minor complications included subcapsular and/or perinephric hematoma, superficial bleeding, arteriovenous fistula and gross hematuria in 12.6, 3.0, 2.5 and 1.4% of biopsy attempts, respectively (27.0, 6.4, 5.5 and 3.0% of biopsies, respectively). Sample adequacy rate was 86.7%, ranging from 82.2 to 94.1% if one or ≥two cores were analyzed, respectively. Residents and consultants yielded similar complication and adequacy rates.Conclusion: According to current literature, ultrasound-guided TER kidney transplant biopsy is a safe and efficient approach eligible for nephrology training.

MO963GRAFT- AND PATIENT-SURVIVAL AFTER FIRST KIDNEY TRANSPLANT BIOPSY

Background and Aims Kidney transplantation is frequently used as a treatment in uremic patients. However, long term function is not easily predicted. The aim of this study was to investigate to what extent histological diagnosis in the first registered transplant kidney biopsy is related to clinical outcome. Method Included were data of 1463 patients (36.6 % women, 63.4 % men) that were merged from a kidney transplantation register and a biopsy register. These patients obtained their first registered transplant biopsy during the period January 1, 2007 until July 30, 2017. Fisher’s exact test and χ-2 analyses were used for cross-tabulation of data. Graft- and patient-survival analysis was performed by Kaplan-Meier analysis with log-rank tests comparing different groups and in next step age and gender adjusted analysis were performed by multivariate Cox-regression-analysis. Data are presented as Hazard Ratio (HR) and 95% Confidence Intervals (CI). A two-sided p-value of <0.05 was considered as statistically significant. Results The graft-survival was shorter for patients with biopsy-proven glomerular diseases (HR 8.1, CI 3.1-20.7) and rejections (HR 4.3, CI 1.7 -10.5) compared to normal biopsy findings. Further, there was a shorter graft-survival for those with chronic damages (HR 3.2, CI 1.3-8.0), acute tubular injuries (HR 3.0, CI 1.2-7.8), and borderline changes (HR 2.9, CI 1.1-7.6). The patient-survival was reduced for patients with biopsy-proven hematological diseases (HR 9.6, CI 2.1-44.0). Sub analysis of all types of rejections showed shorter graft-survival for chronic T-cell-mediated rejection (TCMR) (HR 4.8, CI 2.1-11.7), active antibody-mediated rejection (ABMR) (HR 4.4, CI 2.1-9.3), chronic ABMR (HR 3.8, CI 2.2-6.7), combined chronic ABMR and TCMR (HR 4.0, CI 2.4-6.9) and other rejections (HR 3.3, CI 1.1-9.6) compared to acute TCMR. Patients with TCMR Banff grade II rejection had a better graft-survival (HR 0.35, CI 0.20-0.63) compared to other rejections as well as patients with TCMR Banff grade I (HR 0.52, CI 0.29-0.93). 265 patients had graft-loss and 42 of those patients died afterwards (15.8%). Of the 42 who died after graft-loss 9 patients died within 30 days after transplant failure (21.4%). Conclusion A shorter graft-survival was found in kidneys with glomerular diseases, rejections, acute tubular injuries, borderline changes and chronic damages. A shorter patient-survival was noted for patients with transplant kidney biopsies with hematological diseases. Patients with Banff grade II rejection had a better graft-survival compared to all other diagnosis and other rejections. Further, awareness should be given to patients the first month after graft-loss.

Donor Derived Cell Free DNA Kinetics Post Kidney Transplant Biopsy

Background:Donor-derived cell-free DNA (dd-cfDNA) has generated interest as a biomarker for kidney transplant (KT) rejection. It is possible that the KT biopsy procedure can cause the release of dd-cfDNA, therefore affecting the reliability of this assay in the post biopsy period. In this study we evaluated the effect of KT biopsy on the kinetics of dd-cfDNA.Methods:We conducted a single arm prospective study. Samples were collected from 16 adult KT recipients undergoing KT biopsy. All participants had samples drawn within eight hours prior to the biopsy (pre-biopsy), within 20 minutes (hour 0), 2 hours (hour 2), and 24-48 hours (hours 24-48) after the biopsy. We evaluated the change in dd-cfDNA from the pre-biopsy time point to the following 3 time points after the biopsy.Results:At hour 0 and hour 2, there was a significantly larger log dd-cfDNA mean score compared to the pre-biopsy score [Least square mean (LSM) estimate 0.4 (0.17, 0.63) and 0.39 (0.09, 0.68) respectively]. By 24-28 hours post biopsy there was no significant difference in log dd-cfDNA mean score compared to the pre-biopsy score [LSM estimate -0.21 (-0.6, 0.19)]. Conclusion:KT biopsy leads to an increase in dd-cfDNA after the procedure, however, this rise is transient and resolves by 24-48 hour after the biopsy. Providers can obtain dd-cfDNA level as soon as 48 hours post biopsy with high confidence that the levels have not been affected by the biopsy. In addition, our findings suggest possible non-traditional reasons for increase in dd-cfDNA such as mechanical reasons.