It can be a common problem for those who stand to wee right throughout life. So lets explore why you might miss the target. When we wee at an angle it means that something is changing the flow of our urine, now this could be something as simple as a random hair that is sitting over the end of our penis and causing us to spray or not pulling your foreskin out of way.
Some of us are born with an opening that is at a slightly different position or it could be a problem inside. Such as an infection. This can be caused by many causes and most are due to bacteria that are on our skin or in the environments getting into the urethra. Other causes are sexually transmitted diseases STDs such as gonorrhoea and chlamydia or prostatitis which while strictly not a UTI can cause similar symptoms.
This explains the difference between the descending and ascending curves in Fig. Future studies may incorporate solid modelling of the urethral tissues to understand the temporal dynamics of meatal dilation during voiding and hence the effect on the flow pattern.
The wavelength is a function of both the flow rate and the shape and size of the meatus. The size and shape of the orifice is also characterised by the dilation parameter , such that a reduction in corresponds to an increase in opening.
Note that the relationship is non-linear due to the changes in the meatal opening. We then enlisted a group of 60 male patients who had been referred to a urologist due to low urine flow rate and suspected bladder outlet obstruction associated with prostatic enlargement.
The patients were asked to record the maximum wavelength whilst voiding into a clinical urine flow meter. The flow meter used was a Smartflow Albyn Medical. In addition, the same procedure was performed with a sample of 60 healthy male volunteers with no history of urinary flow problems.
All participants from both groups reported the same characteristic urine flow pattern which evolved over the course of a single void in line with the flow rate, as shown in Fig. For the group of healthy volunteers there was a statistically significant positive correlation correlation coefficient between peak flow rate and maximum wavelength Fig. The patient group showed no statistically significant correlation between and in contrast to the positive correlation for healthy volunteers Fig.
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. 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. Michael Gibson, M. In anatomy , the urethra is a tube which connects the urinary bladder to the outside of the body. The urethra has an excretory function in both genders to pass urine to the outside, and also a reproductive function in the male, as a passage for sperm. The external urethral sphincter is a striated muscle that allows voluntary control over urination. In the human female, the urethra is about inches long and opens in the vulva between the clitoris and the vaginal opening.
Because of the short length of the urethra, women tend to be more susceptible to infections of the bladder cystitis and the urinary tract. A stricture restricts the flow of urine from the bladder and can cause a variety of medical problems in the urinary tract, including inflammation or infection. Explore Mayo Clinic studies testing new treatments, interventions and tests as a means to prevent, detect, treat or manage this condition.
Urethral stricture care at Mayo Clinic. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version.
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