Mieke Bus

7 105 275°. (3) Besides diameter of the scope, the diameter of the working channel is of importance, as it is used for irrigation with water as well as for placement of instruments like graspers, baskets and laser fibers. Maximal deflection of the ureterorenoscope is diminished when instruments are placed in the working channel. This can hamper optimal utilization of the ureterorenoscope. In case of a suspect lesion, histopathological examination is mandatory. Biopsy specimens retrieved during ureterorenoscopy are frequently minute because of the application of small caliber instruments, and may therefore, be difficult to examine by the pathologist. (4) Consequently, a high rate of tumour upgrading (37-96%) and upstaging (38%) is reported following nephroureterectomy. (5, 6) To decide which patients are eligible for endoscopic treatment, information on tumour stage and grade has become imminent for clinical decision-making. Optimizing endoscopic visu- alization and accurate diagnosis of UTUC is therefore, a prerequisite. Novel optical diagnostic techniques, based on the interaction of light with tissue, have the potential to improve the detection and diagnosis of UTUC. (7) These interactions include scattering, absorption and flu- orescence, all of which are characteristic for certain tissue types. Some of these techniques aim to provide real time intra-operative information on tumour grade and stage. If knowl- edge about tumour grade and stage is obtained during URS, a better selection of patients eligible for endoscopic treatment is possible and safe and simultaneous treatment can be applied. It is because of this promise that optical diagnostics might reduce the limitations of the current biopsies. Most research on the application of optical diagnostics on urothelium has been done in the field of bladder cancer. (8, 9) Results on bladder urothelium resemble ureteral urothe- lium. However, the limited space in the ureter and the difficulty of reaching the upper uri- nary tract creates a whole new spectrum of challenges for the applied optical techniques. Given the speed of current technical developments and miniaturization of instruments, optical diagnostics have become available for the diagnostic work up of upper urinary tract investigation. Novel optical diagnostic techniques, based on the interaction between light and tissue, have the potential to improve UTUC visualization. These interactions include scattering, absorp- tion and fluorescence, all of which are characteristic for certain tissue types. Some of these techniques aim at improved visualisation of urothelial tumours (NBI, IMAGE1 S™, PDD), while other techniques aim at providing real time intra-operative information on tumour grade and stage (OCT, CLE). However, research has to be done before endoluminal diagnostics can be reliably applied in the upper urinary tract. Although promising, the diagnostic value of optical diagnostics has not been determined yet. In addition, cost effectiveness has not been determined for these new diagnostic techniques. However, it can be hypothesized that improved tumour