748 US150B US during second urodynamic investigation at 150 ml bladder Wlling US250B US during second urodynamic investigation at 250 ml bladder Wlling SD Standard deviation 95% CI 95% conWdence interval Introduction Ultrasound bladder wall thickness (BWT) measurements became popular for measuring, quantifying, and monitoring bladder outlet obstruction in men [1–5], for detecting detru- sor overactivity in women [6–8], and for assessing urethral valves or abnormal urethral function in children [9, 10] which are all associated with increased BWT. Ultrasound BWT measurements oVer the advantage of detecting non- invasively the bladder wall response to lower urinary dys- function; thus, avoiding expensive, potentially harmful, time- and material-consuming urodynamic investigations in these particular patient groups. Longitudinal studies on bladder outlet obstruction or other forms of bladder dys- function are still missing because patients were not willing to accept repeated urodynamic measurements. Ultrasound BWT measurements might therefore be used for epidemio- logical or clinical studies, in which large number of healthy volunteers or patients can be repeatedly screened and clas- siWed without being submitted to invasive urodynamic investigations. Experienced centers have demonstrated small intra- and inter-observer variabilities of conventional ultrasound BWT measurements in the range of ·5 and 4–12%, respectively [1, 4]. However, this experience originates from single centers and remains limited to a small group of investigators. This, together with the fact that the learning curve is not negligible, might hinder new investigators in employing this technique and limit its widespread use [11]. Therefore, a machine for automatic measurements of BWT is desirable. Such a machine was introduced by Verathon® (formerly Diagnostic Ultrasound®; Bothell, WA, USA). BVM 6500 device is a small, light, battery-powered, porta- ble ultrasound machine that aims to measure BWT and bladder volume automatically and accurately at bladder Wlling volumes between 100 and 400 ml [12]. The 3.7 MHz scanner of BVM 6500 has to be positioned sup- rapubically on the skin of the lower abdomen exactly on the position where the conventional ultrasound array would usually be located for BWT measurements. Via an internet connection, the scanned image data has to be transmitted to a server computer in the USA, where the bladder is delineated and BWT is measured. The scanned images and results are returned to the sender after approxi- mately 2 min. 123 World J Urol (2009) 27:747–753 No study has ever dealt with the repeatability and agree- ment of BWT measurements by either technique which, however, needs to be conWrmed before conducting trials on the clinical usefulness of BWT measurements. We there- fore initiated this study to investigate whether (1) manually and automatically obtained BWT measurements are repeat- able, (2) repeatability depends on bladder Wlling volume, and (3) automatically obtained values are comparable with hand-measured values of an experienced investigator using conventional ultrasound machines. Materials and methods Patients and study design Adult male and female patients with an indication for uro- dynamic investigation in terms of their workup for lower urinary tract symptoms, urinary incontinence, or postvoid residual urine were asked to participate in this prospective study between April and October 2007. The trial was con- ducted according to the regulations of the local ethics com- mittee. All patients were fully informed about the study protocol and gave their consent before the measurements. Examination protocol Each patient was placed in the lithotomy position and the bladder was emptied with a 12 F lubricated transurethral catheter by the investigator. A 6 F transurethral, double- lumen catheter was inserted into the bladder and a 10 F single-lumen catheter into the rectum. The empty blad- der was conWrmed by a suprapubically positioned dynamic 9-4 MHz ultrasound array (iU22; Philips®, Eindhoven, The Netherlands). Afterwards, all patients were transferred to a more convenient sitting position. The bladder was Wlled with sterile saline solution of 37°C at a bladder Wlling rate of 25–30 ml/min. Urodynamic investigations (Ellipse, Andromeda, Taufkirchen, Germany) were performed according to the “good urodynamic practice” standards rec- ommended by the International Continence Society [13]. At 150 ml of bladder Wlling the infusion pump was tem- porarily stopped to measure anterior BWT, Wrst with the bladder scan (BS) BVM 6500 (BS150A) and immediately afterwards with the conventional dynamic 9-4 MHz ultra- sound (US) scanner (US150A), as previously described [3, 11, 14]. The average value of three US measurements at the anterior bladder wall was used for further calculation. BS data were sent to the Verathon® central server via a spe- ciWc internet homepage using a personal login code. In the meantime, the bladder was Wlled until 250 ml and BWT measurements were repeated (BS250A and US250A). After- wards, the bladder was Wlled until the patient reported a