Standardized ex vivo comparison of different upper urinary tract biopsy devices: impact on ureterorenoscopes and tissue quality

To evaluate the influence of different biopsy forcipes on the deflection, irrigant flow, and optical characteristics of flexible ureterorenoscopes and to assess tissue quality for histopathologic evaluation in an ex vivo setting.

The following five different biopsy forcipes were compared: Olympus (FB-56D-1; diameter 5Fr.), R. Wolf (829.601; 3Fr.), Karl Storz Medical (11275ZE; 3Fr.), Boston Scientific (Piranha; 505-160; 3 Fr.), and Cook BIGopsy (115CM; 2.4 Fr.). The devices were tested in 3 different ureterorenoscopes: Storz 11278 VU (Flex-X²), Storz 11278 V (Flex-X^C), and Wolf Cobra (7326071/-6). Tissue samples were obtained from porcine upper urinary tracts.

Baseline irrigation flow rates with empty channels were significantly higher in the Wolf Cobra than in Storz ureterorenoscopes (30.5 vs. 23 and 21 ml/min). The BIGopsy forceps allowed for higher flow rates in both Storz ureterorenoscopes (2.2 and 1.3, respectively) when compared to the other devices (0.5 and 0.6 ml/min). The Storz and Wolf biopsy forcipes resulted in the highest impairment of the deflection angle. In all 3 ureterorenoscopes, flow rates and deflection angle were least impaired by the BIGopsy. However, BIGopsy compromised the field of view (20 % reduction vs. 12 % by others). The largest sample of renal pelvis and ureter biopsies was obtained with BIGopsy and Storz^® forcipes, respectively. The extent of artifacts and denuded urothelium were comparable in all samples.

The various biopsy devices showed different impacts on irrigation flow, deflection, and field of view. The Cook BIGopsy best retains irrigation flow in single-channel flexible ureterorenoscopes and deflection. However, a smaller field of view may complicate handling and tissue acquisition.