Evaluation of a nitinol stone retrieval basket as an alternative to biopsy forceps for biopsy of suspected upper tract genitourinary malignancies

BACKGROUND: The anatomical nature of the ureteroscopic approach for biopsy of upper urothelial tract tumors requires the utilization of small instruments, often limiting biopsy specimen quality. This leads to lower-than-desired tumor grading accuracy and malignancy detection capabilities on the initial evaluation of upper tract tumor specimens. This is problematic because optimal treatment of upper tract urothelial carcinoma (UTUC) depends on early disease detection and subsequent accurate diagnosis. OBJECTIVE: The objective of our study was to compare the biopsy capabilities of two ureteroscopic biopsy instruments – biopsy forceps and the nitinol stone retrieval basket. METHODS: We performed a retrospective analysis of ten patients who underwent biopsy of an upper tract mass with either instrument. Average specimen size, muscularis propria presence, and malignancy detection sensitivity were the variables of interest. RESULTS: The nitinol stone retrieval basket obtained larger biopsy samples than the biopsy forceps, with average biopsy volumes being 0.0674 cm(3) and 0.0075 cm(3), respectively (P = 0.00017); this was the only statistically significant result of our study. Muscularis propria was present in 31% (4/13) of the biopsies with the nitinol stone retrieval basket, whereas 0% (0/5) of the biopsy forceps biopsies contained muscularis propria (P = 0.2778). Regarding malignancy detection sensitivity, the nitinol stone retrieval basket biopsies identified malignancy in 100% of the specimens that had confirmed malignancy; the biopsy forceps only detected malignancy 40% of the time (P = 0.4134). CONCLUSION: These findings suggest that the nitinol stone retrieval basket is a useful diagnostic tool for UTUC, although further investigation is warranted to determine its superiority compared to biopsy forceps.