Urol Res (2011) 39:483–486 DOI 10.1007/s00240-011-0373-y 123 ORIGINAL PAPER Flow matters: irrigation Xow diVers in Xexible ureteroscopes of the newest generation Stephan Kruck · Aristoteles G. Anastasiadis · Georgios Gakis · Ute Walcher · Joerg Hennenlotter · Axel S. Merseburger · Arnulf Stenzl · Udo Nagele Received: 1 November 2010 / Accepted: 7 March 2011 / Published online: 26 March 2011  Springer-Verlag 2011 Abstract The development of new-generation Xexible ureteroscopes has improved diagnostic and therapeutic endourological procedures. Despite technical improvement irrigation Xow and quality of vision is often unsatisfactory. This study describes inter-manufactural diVerences in the latest available Xexible ureteroscopes in terms of irrigation Xow in correlation to diVerent deXection angles and the use of 1.9 Fr. stone baskets. Irrigation Xow measurements were performed in Wve new-generation Xexible ureteroreno- scopes with 3.6 Fr. working channels: Wolf (Uretero-Reno- scope 270°), Storz (Flex-X² and Flex-X c ), ACMI (DUR-D) and Olympus (URF Type P5) in 0°, 90° and 180° deXec- tion. All measurements were carried out Wve times with an empty working channel as well as with inserted 1.9 Fr. stone baskets. Mean Xow rates with empty instruments (SD) counted 50 ml/min (0.8), 50 (1.0), 48 (1.7), 48 (1.6) and 44 (0.7) for ACMI, Wolf, Storz (FlexX² and Flex-X c ), and Olympus, respectively. Stone baskets signiWcantly reduced irrigation Xows in all tested ureteroscopes (p < 0.05). In channels with inserted baskets, the highest Xow rates were measured for ACMI and Wolf with 12 ml/ min (0.7) each. The lowest reduction of Xow rate was detected in the ACMI and the Wolf ureteroscope (76.0%, 38 ml/min each). Measurements after Xexion showed no signiWcant diVerences between the ureteroscopes. Latest generation of Xexible ureteroscopes oVer various new prod- uct developments, including excellent deXection capacities. This study showed inter-manufactural diVerences in terms of irrigation Xow rates with either empty or occupied work- ing channels resulting in signiWcant alterations in endo- scopic view. Keywords Flexible ureteroscopes · Irrigation Xow · Endourology · Upper urinary tract Introduction Technical innovations including improvement of active and passive deXection, decrease in size and development of superior digital visualization have increased the use of endo- urology in diagnosis and management of upper urinary tract pathology. Flexible ureterorenoscopic stone management already has proven to be an alternative and eYcient treat- ment either to shock wave lithotripsy or percutaneous neph- rolithotomy in many cases. Five new Xexible ureteroscopes (Wolf Uretero-Renoscope 270°, Storz FlexX², Storz Flex- X c , ACMI DUR-D and Olympus URF Type P5) with high deXection capacities, ergonomic handling and small 3.6 Fr working channels oVer easy access for suYcient stone workup combined with excellent visualization. The Karl Storz, Flex-X 2 contains a laser-resistant distal tip that reduces laser beam induced damages. It oVers a deXection range of 270° in both directions. According to S. Kruck · G. Gakis · J. Hennenlotter · A. Stenzl Department of Urology, University of Tuebingen, Tuebingen, Germany A. G. Anastasiadis Department of Urology, Eilenriede Clinic, Hanover, Germany U. Walcher · U. Nagele Department of Urology, General Hospital, Hall in Tirol, Austria A. S. Merseburger Department of Urology and Urologic Oncology, Hannover Medical School, Hanover, Germany U. Nagele (&) Department of Urology and Andrology, General Hospital, Milser Straße 10–12, 6060 Hall in Tirol, Austria e-mail: Udo.Nagele@bkh-hall.or.at