Urodynamics (UDS) is essential to evaluate lower urinary function. Cystometry and pressure-flow study provide several important information to characterize and quantify lower urinary tract symptoms (LUTS) in an objective way. UDS is laborious, expensive and invasive. Aiming to obtain similar data, but using less invasive mechanisms, alternative methods have been developed recently, with limited success. On this video, we present a new device, developed by the Biomedical Engineering Centre from our university in association with the Urology Department. The device was previously approved by the responsible technical committee that tested the reliability of its measures. This method is minimally invasive, easy to reproduce and offers reliable results.

The device made of polypropylene, in a cylindrical shape, allows urine flow through it. The connection between the tube and the pressure transducer must be placed at the same level as the pubic symphysis. The patient is asked to gently stretch the penis by the glans, to avoid any bending of the urethra, and to introduce the device into the navicular fossa. Five seconds after starting micturition, the flow should be interrupted by the patient by blocking the end of the urethral device with the index finger. At this moment it is possible to measure the bladder pressure. This step must be repeated at least three times. Therefore, it is possible to measure the isovolumetric bladder pressure with repeated interruptions of the outflow and higher accuracy.

The interpretation of the detrusor pressure and interrupted flow in the minimally invasive procedure differs from UDS. The detrusor contraction converts strength in the outflow. The interruption of the outflow provides bladder pressure, as the isovolumetric pressure. While it is possible to analyse the pressure and flow on the conventional method, only the bladder pressure may be evaluated with the minimally invasive procedure.

Minimally invasive urodynamics is a new method to assess the voiding phase. It does not aim to replace UDS, but to work at an intermediate level between UDS and free uroflowmetry. This new method can provide bladder pressure measures in addition to flow directly and effectively, causing minimal discomfort and risk to the patient. It provides clinically significant information adding minimal burden to the patient. Once this procedure can be easily repeated, it enhances the patient’s follow-up.