Improved filter method for urine sediment detection of urothelial carcinoma by fluorescence in situ hybridization

Context.-Fluorescence in situ hybridization ( FISH) of voided urine sediment is a sensitive and specific test for the detection of urothelial carcinoma. The time required for slide preparation using the conventional cytospin method is lengthy. Objective.-To present an alternative to the conventional cytospin method. Design.-We compared the results of an improved filter monolayer method with published results of the conventional cytospin method. A total of 624 patients with cytology and FISH analyses were followed with cystoscopy and/or bladder biopsy. Fluorescence in situ hybridization analysis was performed on 624 cases using fluorescence-labeled probes to the pericentromeric regions of chromosomes 3, 7, and 17 and band 9p21; cytology was also performed in all cases. Results.-A total of 217 (34.7%) of 624 patients had follow-up bladder biopsies, and 170 of these (78.3%) had urothelial carcinoma. The sensitivity for cancer detection was higher for FISH than for urine cytology (92.9% [158/170] for FISH vs 72.9% [124/170] for urine cytology, P = <5%). The specificity was equivalent for FISH and urine cytology (97.5% [443/454] for FISH vs 92.2% [419/454] for cytology). The sensitivity for FISH was better ( 92.9% vs 81%), and there was no significant difference in specificity (97.5% vs 96%) between the filter method and the conventional cytospin method. Unlike the conventional cytospin method, the filter method did not require multiple centrifugation and decantation steps or investment in dedicated equipment. Conclusions.-The improved filter method was faster, easier, and less expensive than published results with the conventional cytospin method with better sensitivity and equivalent specificity.