Optimizing renal biopsy: efficacy and safety of the ultrasound-guided tangential approach.

Objective: To present the results of a series of outpatient renal biopsies performed with a tangential approach, as well as to conduct an analysis focusing on patient safety and the frequency with which sufficient material was obtained.

Materials and methods: This retrospective observational study examined the pathology results and evolution of 244 patients referred for ultrasound-guided renal biopsy at a single center. In each biopsy, the needle was advanced in the cortex just below the renal capsule. The pathologist examined the fragments, counting the viable glomeruli obtained; additional punctures were performed if necessary, as long as Doppler ultrasound showed no bleeding. The patients remained at rest at the clinic, being discharged after a follow-up ultrasound evaluation and contacted one week later to investigate late adverse events.

Results: Ten patients were excluded from the analysis, leaving a sample of 234 patients. The material obtained for diagnosis was considered sufficient in 95.73% of the procedures, partially adequate in 3.42%, and not very representative in 0.85%. Two patients (0.85%) had bleeding greater than 50 cm³ and were referred to the hospital emergency department. Both of those patients had a favorable evolution: one required only a period at rest, and the other required a blood transfusion, being discharged 48 h after the procedure.

Conclusion: The tangential approach to renal biopsy, with its high rates of safety and efficacy, representing a reliable diagnostic tool for renal and systemic diseases, should be the method of choice for obtaining adequate pathological specimens.