After standard UDS were completed, the bladder catheter was removed, and post void residual was determined as the difference between the infused and voided volume during the study. The UM was then inserted per urethra, followed by placement of standard urodynamic catheters, and a second cycle of UDS was performed while recording simultaneously from both systems. Post void residual was again measured. The bladder and rectal catheters were then removed, and the patient ambulated around the clinic. Bladder filling occurred naturally while the monitoring system recorded intravesical pressure, until each patient voided at least one additional time, this time privately on a toilet in the bathroom with the door closed.
A portable ultrasound was used to determine post void residual once again. There were no significant differences in pre procedure pain compared to pain immediately after the procedure and at 48 hours. The monitor detected 98% of urodynamic events as seen on the conventional UDS tracing. It seemed particularly good at detecting detrusor over activity. Two subjects were unable to void during UDS. In these patients, the bladder catheter was removed to enable voiding while the UM continued to transmit intravesical pressure. An additional 3 subjects were able to avoid only small volumes during UDS, but emptied almost completely during the catheter-free void with the UM in place. The patients exhibited A significantly lower post void residual during the ambulatory phase compared to the 1st and 2nd cycle of UDS. Pressures measured simultaneously with both systems demonstrated high agreement with variability between individual subjects. The presence of the UM did not result in earlier sensation or decreased capacity. The largest difference in urodynamic outcomes was observed in increased pressure at peak flow with the UM system, although this difference was not statistically significant. There was no significant increase in detrusor over activity events attributable to the UM device.
We all acknowledge that traditional urodynamics remains artificial in the sense that bladder filling is retrograde and rapid, compared to normal fill rates, and voiding occurs around a catheter in an unfamiliar setting. As opposed to previous ambulatory urodynamics, this system does not require an indwelling catheter of any size. Some of the advantages cited for previously reported ambulatory urodynamic studies were the ability to detect voiding in patients with “bashful bladders” and to detect contractility in patients without any bladder contractility evident on standard urodynamic studies. The authors also point out that previous studies have shown that the presence of traditional urodynamic catheters can significantly alter voiding flow rate compared to free flow studies. They also note that this effect cannot be completely explained by the volumetric impact of the catheter and may relate to insufficient sphincter relaxation in the presence of an indwelling catheter, no matter how small. They also point out that this new monitoring system can capture long recordings of catheter-free bladder data.
The authors point out limitations to their study and the current system. They did not insert urodynamics catheters during the ambulatory phase for correlation with the UM system. The UM measures at this point only intravesical pressure and is not capable of filtering out abdominal events. Interpretation requires experience to recognize the detrusor pressure from only vesical pressure measurement. The current device does not measure volume, so it cannot yet replace all outcomes of UDS.
What is the future of such a device? More physiological? Yes. Currently more difficult to interpret? Yes. Adaptable to both men and women? Should be. Current algorithms are being developed to extract the detrusor pressure from total intravesical pressure. Small devices to monitor intra-abdominal pressure are apparently being developed; this would considerably simplify the situation with respect to interpretation. The ideal would be a painless process for measuring ambulatory urodynamics accurately, with flow capabilities that eliminate the need for a dedicated room and additional equipment. A further refinement would be the development of an accurate large language model to automatically interpret, along with an accurate clinical history, the study. Interestingly, the subject of automated interpretation of urodynamic parameters, with performance exceeding that of junior urologists and approaching that of senior urologists, is discussed in another article in that same journal.3 The addition of a video unit and the methodology required for those patients requiring video urodynamics needs to be considered. The price of such a system for an individual patient and the responsibility for payment are obviously other critical considerations. Finally, will urologists, urogynecologists, and other specialists who practice or utilize current methodology be willing to adopt something new? Time will tell.
Disclosure: Dr. Wein is an advisor to Bright Uro, the company to which this technology has been licensed
Written by: Alan Wein, MD, PhD, FACS, Professor of Clinical Urology, Department of Urology, Desai Sethi Urology Institute (DSUI), University of Miami Miller School of Medicine, University of Miami Health Systems, Miami, FL
References:
- Frainey, B et al, First human subjects testing of the UroMonitor: A catheter-free wireless ambulatory bladder pressure monitor. J. Urology, 2023, 210: 186-195
- Gross, M et al, Validation of a wireless catheter-free ambulatory urodynamics device in women with neurogenic bladder. Neurourology and Urodynamics, 2026, 45: 96-104
- Wang, Z et al, Application of large language models in automated interpretation of urodynamic parameters, Neurourology and Urodynamics, 2026, 45: 84-95