Repeat noninvasive bladder pressure measurements with an external catheter

Purpose: Previously it has been shown that an objective diagnosis of infrav esical obstruction can be made by combining the maximum flow rate and isovo lumetric bladder pressure. We evaluate a noninvasive method to measure isov olumetric bladder pressure to help develop a noninvasive modality for diagn osing obstruction. Materials and Methods: An external catheter consisting of an incontinence c ondom, tube and pressure transducer was used. Flow rate through the cathete r was remotely interrupted to measure the bladder pressure in the condom. T wo series of measurements were done in 11 healthy male volunteers. In the f irst series we determined whether voiding was affected after flow rate inte rruption. In the second series we analyzed repeat pressure measurements of 1 voiding to determine whether maximum isovolumetric pressure depended on b ladder volume. Results: Flow rate was unaffected after interruption for pressure measureme nt. Repeat measurements of isovolumetric bladder pressure demonstrated that the pressure depended significantly on bladder volume. Average maximum iso volumetric pressure was 12.2 kPa. at a bladder volume of 251 ml. Conclusions: As no inhibition of voiding was noted after a single pressure measurement, repeat noninvasive measurements can be made on voiding. With r epeat measurements the dependence of isovolumetric bladder pressure on blad der volume can be considered to obtain a reliable estimate of pressure as a basis for a noninvasive diagnosis of obstruction.