FDA on Urethra. CDC on Urethra. Books on Urethra. Urethra in the news. Be alerted to news on Urethra. News trends on Urethra. Blogs on Urethra. Definitions of Urethra. Patient resources on Urethra.
Discussion groups on Urethra. Patient Handouts on Urethra. Directions to Hospitals Treating Urethra. Risk calculators and risk factors for Urethra. Symptoms of Urethra. Diagnostic studies for Urethra. Treatment of Urethra. CME Programs on Urethra. Urethra en Espanol. Urethra en Francais. Urethra in the Marketplace. Patents on Urethra. List of terms related to Urethra. Editor-In-Chief: C. For the patient group, the dilation parameter was statistically different and exhibited greater variability than that for healthy men Fig.
Notably some patients with low peak flow rates showed higher values of the dilation parameter indicative of a reduced meatal opening. A reduction in a patient's meatal opening might be expected at very low flow rates where there is insufficient flow to fully open the meatus Fig. Nonetheless, meatal dilation also appeared to be reduced in patients that have regained a more normal flow rate Fig. It is possible that the reduced urethral opening reflects the greater average age of the patient cohort and associated age-related urethral stiffening [14].
However there was no correlation between age and dilation parameter with younger patients also showing high values. Thus an alternative explanation is that the chronic low flow rates in these patients may lead to urethra atrophy or constriction and that this persists even after the prostatic urethral obstruction causing the low flow rate is reduced.
Although it is unclear for how long such an effect might persist, our data is supported by clinical experience which suggests that certain patients may benefit from surgical dilation of the urethra in order to regain a normal flow rate [15]. Thus, our data and the resulting nomogram shown in Fig. A peak flow rate was considered as abnormally low red region. The green region represents the confidence envelope for values based on data from the normal group.
Individuals with and values within the yellow region have a normal flow rate but reduced urethral dilation. Accurate estimation of an individual's peak urine flow rate based on measurements of maximum wavelength can be performed if an individual's meatal dilation is calibrated for. Self measurement of an individual's urine flow pattern and maximum wavelength can provide a simple non-invasive method for monitoring peak urine flow rate as part of the recommended practise of watchful waiting for patients with benign prostatic hyperplasia [17] — [20].
This has advantages over existing uroflowmetry techniques in that it is completely non-invasive, simple and cheap to implement and avoids inaccuracies associated with voiding in a clinical setting and obtaining data from a single void [7] , [21] — [24].
For the group of healthy volunteers the statistically significant positive correlation gave the following relationship between and 10 where is found to be. The accuracy of this estimate of is 2 standard deviations. However this can be greatly improved by precalibrating for an individual's meatal geometry.
This could simply be achieved by requesting the patient to void into a standard urine flow meter to obtain the relationship between and. This approach would also provide a non-invasive measurement of an individual's meatal dilation during voiding. This is demonstrated in Fig. The figure shows the uncertainty in the estimate of was improved to 2 standard deviations. The closed symbols show the predicted based on an individual's measured at the first recorded voiding event.
The open symbols show the increased scatter if the sample mean value is used rather than the individual's. In this report we have applied an understanding of capillary wave phenomena in liquid jets to reveal the biophysics behind the characteristic shape of the urine flow stream and how this can be used as a simple non invasive means of measuring urethral opening and urine flow rate.
The data obtained in the present study included inaccuracies caused by poor estimates of which are likely to be exacerbated by obesity, poor eye sight, or lack of manual dexterity. However despite the associated scatter there was still a statistically significant correlation between and for healthy volunteers, showing that an individual's peak urine flow rate can be estimated from self measurement of maximum wavelength.
Thus this technique can provide a simple non-invasive method for monitoring peak urine flow rate as part of the recommended practise of watchful waiting for patients with benign prostatic hyperplasia [17] — [20]. All volunteers gave signed consent to the trial which was approved by the local ethics committee at Queen Mary University of London Ethics Application No.
Healthy volunteers were recruited from staff and students within the University. Rigid walled orifice geometries used in the experimental work were manufactured using a rapid-prototyping technique within a 0. Orifice circumference was varied from 6 to 33 mm to reflect the physiological range in urethral dimensions. The nozzles were designed to have a length of 50 mm section to ensure a straight walled channel of fixed cross-sectional shape prior to the exit orifice, thus ensuring minimal expansion or contraction of the jet at the nozzle exit.
Liquid water was supplied at mains pressure and preset physiological flow rates of 5 to Imaging of complete voiding events was conducted for a health male volunteer. A scale rule was held alongside and parallel to the urine stream to enable the instantaneous wavelength to be measured from the video images.
The temporally varying flow rate was measured using a clinical gravimetric urine flow meter. Data was adjusted for the 0. Sixty healthy volunteers and sixty patients, mean ages 1 standard deviation were 26 8 and 67 13 respectively, were asked to void normally into a clinical urine flow meter and to record the maximum wavelength in their flow stream.
Individual data consisted of the maximum wavelength, the corresponding peak flow rate, the total voided volume and the subject's age. Procedures were conducted in private with approval of the local ethics committee. We wish to thank all those that took part in the human studies and also to Albyn Medical for the loan of a gravimetric urine flow meter. Conceived and designed the experiments: AW MK.
Wrote the paper: AW MK. Clinical support with patient trial: NB. Computational modelling: AW. Browse Subject Areas? Click through the PLOS taxonomy to find articles in your field. Abstract We develop a new computational model of capillary-waves in free-jet flows, and apply this to the problem of urological diagnosis in this first ever study of the biophysics behind the characteristic shape of the urine stream as it exits the urethral meatus.
Introduction The analysis of urine flow rate is important in the diagnosis of urinary conditions ranging from neuromuscular pathologies to bladder outlet obstruction [1] — [3]. Computational Methods For the computational simulations of the urine stream we make use of a novel method which replicates the jet shape from an orifice by simulating the unsteady development of a 2-dimensional droplet deforming under the action of surface tension.
Modelling non-axisymmetric jets When a liquid jet issues from a non-cylindrical aperture, the jet formed tends to undergo large deformations under the action of surface tension. Download: PPT. Figure 1. Sketch of the liquid jet flow exiting an elliptical orifice. Figure 2. Experimental and computational models describe the shape of the urine flow pattern. Figure 3. Computational modelling solves the 3-dimensional jet flow from a wide range of orifice shapes. Figure 4. Experimental and computational models show the influence of flow rate and orifice size and geometry on the shape of the jet flow.
Results and Discussion In-vivo trials Having developed the theory explaining the flow pattern associated with an elliptical orifice, we now examine the real flow pattern for urine exiting the meatus and the changes which occur during a single void.
Figure 5. The human urine flow stream shows a characteristic pattern that is dependent on flow rate and orifice dilation as predicted by the experimental and computational modelling.
Figure 6. Self measurement of the maximum wavelength provides an estimate of the peak urine flow rate for healthy males, but requires individual calibration for patients undergoing treatment for urethral obstruction.
Figure 7. Flow rate measurement accuracy can be improved if an individual's dilation parameter is calibrated for. Materials and Methods Ethics statement All volunteers gave signed consent to the trial which was approved by the local ethics committee at Queen Mary University of London Ethics Application No.
In vitro Experimental Modelling Rigid walled orifice geometries used in the experimental work were manufactured using a rapid-prototyping technique within a 0.
The evacuated urine was observed in all of the process of urine micturition. We focused on the shape of evacuated urine stream at Qmax and terminal voiding to compare the evacuated urine shape and velocity of urine. Two healthy volunteers with 0 of international prostate symptom score participated in the third sub-study. The evacuation of urine was observed in 4 times in total. The mean of Qmax and voided volume is The anti-crock vorticity of evacuated urine flow was observed in all of observation.
The representative findings high-speed camera images at Qmas and the terminal voiding were shown synchronizing with uroflowmetry in Figure. The vorticity was clearly observed in all of the process of urine evacuation. The first twist, the beginning of vorticity was detected at 6 cm from the external orifice approximately, when the urine flow reached at Qmax fig. The voided urine generated vorticity closing to urethral orifice, and the vorticity changed to spiral shape increasing distance from urethral orifice, especially at the end of urine micturition fig.
Interpretation of results. This is the first report to detect of urine vorticity and to investigate the relationship between vorticity and LUT function. As shown in the obtained results, high-speed video-camera is useful assessment to evaluate urine vorticity in voided urine dynamically and safely.
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