Vorticity in lower urinary tract can be assessed and associates with urinary tract morphology in men

Abstract

Objectives: The aim of this study is to develop a method to evaluate the fluid dynamics of urine flow in the lower urinary tract (LUT), especially that of vorticity. Materials and Methods:This investigation included three sub-studies to demonstrate urine flow in the entire LUT. First, we attempted to observe vorticity generation in the urinary bladder during spontaneous voiding using transabdominal color Doppler ultrasonography (CDUS). Second, we performed transrectal CDUS to evaluate the vorticity of urine flow in the prostatic urethra. Patients with prostate cancer were enrolled before robotic surgery and divided into the vorticity and nonvorticity groups based on CDUS findings for comparisons of longitudinal urethral diameter and prostatic urethral angle. Third, the vorticity of the voided urine stream was observed using a high-speed video-camera. Micturition was done in a standing position while synchronously monitored for urine flow using uroflowmetry.Results: Vorticity formation could be dynamically demonstrated in the urinary bladder and prostatic urethra using CDUS. The prostatic urethral angle of the vorticity group was more than that of the non-vorticity group. High-speed video recording could clearly capture vorticity and spiral shape generation in voided urine. The distance from the external urethral orifice to the first twist changed in accordance with urine flow rate. Conclusions: In a series of sub-studies, this investigation proved vorticity generation in the LUT and voided urine. Vorticity was detectable in the LUT and in voided urine using CDUS and a high-speed video-camera. Vorticity generation might be associated with urethral morphology. K E Y W O R D S fluid dynamics, lower urinary tract, urodynamics, vorticity Abbreviations: CDUS, color Doppler ultrasonography; LUD, longitudinal urethral diameter; LUT, lower urinary tract; PUA, prostatic urethral angle; Qmax, maximum urine flow rate; US, ultrasonography; VFM, vector flow mapping.

Kidney–Urinary Tract Involvement in Intermediate Junctional Epidermolysis Bullosa

“…Like clinical manifestations in the skin, those in the kidney and urinary tract are caused by fragile tissues and subsequent tissue repair or scarring. The male urogenital tract’s anatomy is by nature more prone to excessive mechanical flow and tension, which may favor involvement of the male urethra, but female patients are probably also affected . Not all of the male patients had urethral manifestations, suggesting that mechanical triggers are additionally necessary.…”

Initial clinical results of fluid dynamical approach for lower urinary tract function using a high‐speed video camera

“…Voided urine flow can be evaluated as a physical phenomenon using fluid dynamics. We previously analyzed voided urine flow using a high‐speed video camera (HSVC) and observed the shape of voided urine 1 . Thus, voided urine speed and shape may reflect the function of the lower urinary tract (LUT), especially for bladder outlet obstruction (BOO).…”

Novel CFD modeling approaches to assessing urine flow in prostatic urethra after transurethral surgery

“…It is also the main link behind the post-surgery improvement in the urination function 2 . Recent studies have demonstrated that the vortex, recognized for its fluid energy loss 2 , occurs in the obstructed PU during spontaneous voiding in preoperative patients 3 , as well as in the completely-hollowed PU during emptying using equipment just after the surgery for BPH 4 . It follows that expansion, one of the forms of deformation, may also affect urine flow in a manner similar to obstruction.…”

“…Since previous experimental studies have evidenced the occurrence of the vortex in the PU both prior to or during surgery 3,4 , the Reynolds averaged Navier-Stokes equation (RNG k-epsilon turbulence model) was applied to simulate the urine flow status. A second-order pressure discretization scheme was applied for pressure calculations, while a second-order upwind scheme was utilized for momentum and turbulence transport equations.…”