Current Topics in TransplantationRenal transplantationHigh Resistive Index in Transplant Kidneys Is a Possible Predictor for Biopsy Complications

•An RI ≥0.8 indicates a greater risk for major and overall complications and should warrant greater caution after kidney transplant biopsy.•These new findings can be important for the planning of biopsies and the follow-up of patients after biopsies from transplant kidneys and for improving patient safety.•The multiple regression analysis showed that in the group <0.8, the RI correlated only with age (P < .001), whereas in the group ≥0.8, RI correlated only with the degree of interstitial fibrosis (P = .003).

BackgroundTransplant kidney biopsies are performed to determine a histological diagnosis for specific patient treatment. The aim of this study was to investigate if Resistive Index (RI) could be a predictor for biopsy complications.MethodsIn this study, 220 consecutive transplant kidney biopsies (136 men and 84 women; median age, 55.5 years) were prospectively included. RI (median, 0.7) was measured by use of ultrasound. Histological diagnoses and biopsy complications were registered. Biopsy needles were either 16- or 18-gauge. Biopsies were performed by radiologists and were carried out as an outpatient procedure (70%) or an inpatient procedure (30%). Usually three passes per biopsy were performed.ResultsThe overall complication rate was 6.8%, divided into major (4.5%) and minor (2.3%) complications. An RI ≥0.8 predicts major (13.3% versus 3.2%; risk ratio [RR], 4.2; confidence interval [CI], 1.3-14.1; P = .03) and overall biopsy complications (16.7% versus 5.3%; RR, 3.2; CI, 1.2-8.6; P = .04) compared with RI <0.8. In the group <0.8, RI correlated with age (rs = 0.28, P < .001) and systolic blood pressure (rs = 0.18, P = .02). In the group ≥0.8, RI correlated with degree of interstitial fibrosis (rs = 0.65, P = .006) and systolic blood pressure (rs = 0.40, P = .03). The multiple regression analysis showed that in the group <0.8, the RI correlated only with age (P < .001), whereas in the group ≥0.8, RI correlated only with the degree of interstitial fibrosis (P = .003).ConclusionsAn RI ≥0.8 indicates greater risk for major and overall biopsy complications and should result in greater caution after biopsy.