[1] Univ Med Ctr, Dept Urol, D-79106 Freiburg, Germany
[2] Univ Med Ctr, Dept Anesthesiol, D-79106 Freiburg, Germany
[3] Univ Med Ctr, Dept Gen & Visceral Surg, D-79106 Freiburg, Germany
[4] Univ Med Ctr, Inst Med Biometry & Med Informat, D-79106 Freiburg, Germany
[5] Med Univ Vienna, Dept Urol, Vienna, Austria
[6] Southmead Hosp, North Bristol NHS Trust, Dept Urol, Bristol, Avon, England
[7] Royal London Hosp, Bartshealth NHS Trust, Dept Urol, London E1 1BB, England