Added Benefit and Risk of an Additional Biopsy or Targeting With Contrast-Enhanced Ultrasound for Patients With Renal Transplants

Objectives: To determine whether renal transplant diagnoses substantially change when 2 biopsy sites are chosen and whether contrast-enhanced ultrasound (CEUS) has value for targeting the second site.

Methods: We prospectively enrolled 40 patients undergoing ultrasound-guided renal transplant biopsy within 2 years of transplant: 20, surveillance; and 20, for cause. A CEUS examination was performed to identify cortical regions with subjectively altered flow. One biopsy was performed at the operator-preferred (primary) site regardless of CEUS findings. Another biopsy was done at a second location, either targeted to an area in which CEUS perfusion findings differed from the primary site (targeted) or at a random location (secondary) if no other area differed. Specimens were randomly labeled A or B; pathologists were blinded to the CEUS result and biopsy location. Location-specific CEUS assessments were recorded. Pathologic results were compared, including acute and chronic Banff scores and any new findings from the targeted or secondary biopsy.

Results: Forty patients were enrolled between January 2016 and December 2018. No location-specific pathologic differences correlated with differences in CEUS assessments. The second biopsy provided additional information that changed management in 4 of 40 patients (10.0% [95% confidence interval, 2.8%-23.7%]). Major bleeding complications occurred in 3 of 40 (7.5%) patients.

Conclusions: Contrast-enhanced ultrasound targeting was not useful. Major bleeding complications were higher than expected, possibly due to the additional biopsy away from the operator-preferred location. Obtaining a second renal transplant biopsy from a substantially different area than the initial operator-preferred location provided additional clinically useful information in 10% of patients.