Is the impaired flow after hypospadias correction due to increased urethral stiffness?

Urinary flow rates in anterior hypospadias: Before and after repair and its clinical implication

Context

Hypospadias is a common urological anomaly which could be surgically corrected with good cosmetic results.

Aims

We aimed to detect changes in urinary flow parameters both before and after tubularised incised plate urethroplasty (TIPU) using uroflowmetry.

Settings and Design

Data collected were clinically implemented hypothesising the probability of urethrocutaneous fistula following stricture with Qmax variation.

Materials and Methods

This study is a prospective analysis done from December 2017 to October 2019. A total of 104 cases of anterior hypospadias were included in the study. A single surgical unit did TIPU. Pre-operative and post-operative uroflowmetry was done, and Qmax was recorded at 3 months, 6 months and 1 year after surgery. Mean Qmax was calculated for all intervals. A significant decrease in Qmax of a child (<2 standard deviation) was ascertained. Urethral calibration was done in those cases with a significant decrease of Qmax and analysed statistically.

Results

The mean age was 6.97 ± 2.41 years. Out of 104 children, 73 (70.2%) and 31 (29.8%) had distal and mid-shaft hypospadias, respectively. The pre-operative mean Qmax of the population was 6.20 ± 0.42 ml/s. Arithmetic mean Qmax at 3 months, 6 months and 1 year was 8.53 ± 0.42, 11.18 ± 0.47 and 13.71 ± 0.44 ml/s, respectively. On comparing the pre-operative with post-operative mean Qmax, a significant increase was found postoperatively (P < 0.0001). Twenty-four patients had significantly decreased Qmax value after 6 months. In these patients, follow-up urethral dilation was done with significant improvement.

Conclusion

The changes in maximum flow rate (Qmax) are suitable for use in routine follow-up. A significant decrease in Qmax over time indicates the onset of urethral stricture. These cases are to be intervened before venturing to redo urethroplasty.

Age-dependent histomorphometric evolution of the corpus spongiosum

Purpose:

To quantify the age-dependent changes in the relative volume of elastic fibers, collagen fibers and the proportion of collagen types I/III in the corpus spongiosum of rats.

Methods:

Forty-eight rats, raised under similar conditions, were divided into four groups (G1 to G4) and underwent penectomy at the ages of 6, 9, 12 and 24 months, respectively. Histological sections from the middle segment of the penis were stained with Weigert’s resorcin-fuchsin, Masson’s trichrome and Picrosirius red, the volumetric density of elastic fibers, collagen fibers and the proportion of collagen types I and III in the corpus spongiosum were determined by stereological analysis.

Results:

A reduction in the proportion of collagen I/III between the groups G3 and G4 (p < 0.048) was observed. In the volumetric analysis of elastic fiber, we observed a significant rise between the groups G2 and G3 (p < 0.03) and a reduction of the volume between the groups G3 and G4 (p < 0.01). However, there was no difference in the quantity of total collagen between the groups (p > 0.54).

Conclusions:

Aging in rats did not change the quantity of total collagen but reduced the proportion of collagen types I/III and the volume of elastic fibers.

Validity and reliability of a home-based, guardian-conducted video voiding test for voiding evaluation after hypospadias surgery

Purpose

To investigate the validity and reliability of a home-based, guardian-conducted video voiding test for assessing postoperative voiding function after hypospadias surgery.

Materials and Methods

In a single center, patients who had undergone urethroplasty by a single surgeon and postoperative uroflowmetry and video voiding tests conducted between 2008 and 2016 were retrospectively reviewed. Urinary stream was categorized into five grades by three pediatric urologists in a blinded manner. The primary outcome was statistical correlation across raters as measured by Spearman correlation coefficient to validate the interpretation of the video voiding test. The secondary outcome was the reliability of the voiding video test compared with maximum urinary flow rate assessed by uroflowmetry.

Results

Thirty-one patients with hypospadias were enrolled. The patients' average ages were 12.3±3.2 months (range, 8–21 months) and 42.8±3.9 months (range, 35–48 months) at the time of surgery and voiding video tests, respectively. Hypospadias was anterior, penile, and proximal in 1 (3.2%), 18 (58.1%), and 12 (38.7%) patients, respectively. The number of patients with each voiding stream grade was as follows: very poor, 4; poor, 4; fair, 13; good, 4; and very good, 6. All intraclass correlation coefficients of the stream grade among the three observers were >0.95. Correlation between the maximum flow rate obtained by use of conventional uroflowmetry and the video voiding stream grade was validated (rho 0.778, p<0.001).

Conclusions

The home-based guardian-conducted video voiding test is easy to perform and the present results demonstrate its validity and reliability for assessing patients' post-urethroplasty voiding pattern.

"Fossa navicularis" and "septum glandis": A "flow-control chamber" for the male urethra?

A clear understanding of the normal anatomy of the glanular urethra is essential for anatomical reconstruction of the male urethra. In hypospadias surgery, tubularization of the neourethra over a catheter or stent has been the standard method for decades. However, the male urethra is not a tubular structure with uniform configuration and diameter by forming a fossa (navicularis) in the glans penis. We recently investigated the structural anatomy of the glanular urethra using magnetic resonance imaging (MRI). We have shown that the male urethra does not have a uniform tubular structure and not covered by the corpus spongiosum to the end. The glanular urethra that forms the "fossa navicularis" has a wider caliber than the proximal urethra. Its vertical elliptical shape resembles a laterally compressed slit-like passage. The fossa navicularis is covered by a thin layer of fibrous tissue ("septum glandis") which is an extension of tunica albuginea of the corpus cavernosum and the corpus spongiosum. Our hypothesis is based on the results of MRI of the glanular urethra and the basic principles of fluid dynamics. We analyzed the flow dynamics of urine on this particular component of the urethra in terms of shape and structural properties. Because of its wider caliber than the proximal urethra, the glanular urethra (fossa navicularis) should cause an increase in pressure and a decrease in velocity of the urine flow. The navicular shape of the fossa and its elliptical external opening (the meatus) should allow urine to be expelled at higher flow rates and at opposite angles at the upper and lower corners which make the wave-like shape of the urine. It can be said that the changes in the volumetric form, pressure and velocity, as well as the wave-like shape of the urine flow are caused by the "fossa navicularis" covered by the "septum glandis". We propose that the "fossa navicularis" and "septum glandis" play a role as 'flow control chamber" in controlling the flow of the urine exiting the urethra, which must be taken into account for successful functional reconstruction of hypospadias.

Can Grafted Tubularized Incised Plate Urethroplasty be Used to Repair Narrow Urethral Plate Hypospadias? Its Functional Evaluation Using Uroflowmetry

Aim:

Using uroflowmetry, the aim of this study is to determine the functional results of the grafted tubularized incised plate (GTIP) urethroplasty used to repair poor urethral plate hypospadias.

Settings and Design:

Seventy-one patients (mean age: 5.7 years, follow-up: 1–5.5 years) were selected from those who underwent surgery using the GTIP technique from 2013 to 2015 at our institution.

Methods:

Patients included were able to void voluntarily and had no fistula. The flow pattern, maximum urinary flow rate (Q_max), voided volume (vv), average flow rate, and voiding time were measured. The results were expressed as percentiles and interpreted according to Siroky nomogram. The Q_max was considered normal if >25^th percentile, as equivocally obstructed when in the 5^th–25^th percentile, and obstructed if <5^th percentile.

Results:

Hypospadias was distal in 45, mid penile in 17 and proximal penile in 9. The uroflow curve was bell-shaped in 24 (30%), interrupted in 9 (14%), slightly flattened in 31 (46%), and a plateau in 7 (10%). Flow rate nomograms revealed that 49 (68%) were above the 25^th percentile, 9 (17%) were below the 5^th percentile, and 13 (15%) were between these ranges. Eleven patients showed improvement in the flow curve and maximum urinary flow rate (Q_max) in follow-up uroflowmetry.

Conclusion:

GTIP repair provides satisfactory functional results. A long-term follow-up is needed to confirm these results.

The biomechanical properties of the urethra in boys with hypospadias: a preliminary study

PURPOSE

The ventral aspect of the penis in boys with hypospadias is composed of dysplastic tissue of the skin and the urethra. The aim of this study was to assess the pre-operative size and biomechanical properties of urethrae in boys with and without hypospadias using a more objective catheter-based system.

MATERIALS & METHODS

In this non-blinded clinical observation study, the study population consisted of 19 boys with hypospadias-the case group (median age 13.9 months [range: 12.2-21.3])-and seven boys without hypospadias-the control group (median age 8.5 months [range: 3.8-18.1]). Modified measurements of impedance were used to assess the size, compliance and viscoelasticity of the urethrae under stepwise increased pressures (between 0, 40 and 60 cmH₂O) using a customised Endolumenal Functional Lumen Imaging probe (EndoFLIP®).

RESULTS

The sizes of the urethrae in boys with hypospadias are variable but tend towards being narrower and less compliant than those of the control subjects i.e. median diameter for meatus urethra was 3.2 mm (range: 2.98-3.92) in the hypospadias group compared with 3.64 (range: 3.22-4.44) in the control group at 40 cmH₂O, and the median change in diameter at meatus urethra was 0.08 mm (range: -0.02 to 0.52) in the hypospadias group compared with 0.23 mm (range: -0.02 to 0.34) when the pressure was increased from 40 to 60 cmH₂O. This biomechanical analysis found that there was no significant viscoelasticity of the urethral meatus in both the groups, whereas the remainder of the urethral structure generally had viscoelastic properties in the control group, seen as a creep on the time/diameter curves (Figure). In the group of boys with hypospadias, evaluations of the urethrae revealed varying viscoelastic abilities, ranging from abilities that were comparable with those of the control subjects to no sign of viscoelasticity at all.

CONCLUSIONS

This study is the first to measure the biomechanical properties of the urethra in children, which might help to provide an understanding as to the structural and functional changes associated with hypospadias. The urethrae in the subjects with hypospadias were variable in diameter but tended to be narrower overall, especially in the distal portion of the urethra. Furthermore, the urethrae in boys with hypospadias were frequently less viscoelastic than those of controls.

CLINICAL RELEVANCE

The EndoFLIP® system may be a future way of objectively estimating the severity of a urethral obstruction and could potentially be included in the postoperative assessment of patients with signs of hampered voiding.

Role of uroflowmetry before and after hypospadias repair

Aims:

To study the role of uroflowmetry in the preoperative and early postoperative period in children undergoing hypospadias repair.

Materials and Methods:

Twenty-six cases undergoing hypospadias repair over 1 year (tubularized incised plate [TIP] Snodgrass [17 patients], TIP with Snodgraft [5 patients], Duckett's onlay flap [2 patients], and Duckett's tube [2 patients] urethroplasty) were prospectively evaluated with preoperative ultrasound and uroflowmetry and postoperative uroflowmetry at 3 months after the surgery and at 6 and 9 months interval if these dates fell within the study period on follow-up. The parameters studied were maximum flow rate (Q_max), average flow rate (Q_av), total voided volume, voiding time, and type of curve. Preoperative and postoperative uroflow data were compared.

Results:

Twenty-six cases comprised of anterior hypospadias (n = 8), mid penile (n = 11), and posterior hypospadias (n = 7). Fourteen patients had obstructed flow rates preoperatively. While 69% patients (18/26) had obstructed flow rates at 3 months postoperatively, it dropped to 43% at 9 months. Following TIP (Snodgrass) repair, 88% (15/17) had obstructed flow rates postoperatively. Best results were seen in patients undergoing circumferentially epithelialized urethral reconstruction (TIP with Snodgraft, Duckett's onlay flap, and Duckett's tube).

Conclusions:

Abnormal uroflow is an inherent aspect of hypospadias in 50% of the cases. Both preoperative and postoperative uroflow evaluation is necessary for meaningful conclusion. Patients with preoperative normal flow rates but obstructed postoperative flow rates need clinical evaluation. Obstructive flow rates are more common after TIP (Snodgrass) repair. The urinary flow rates improve with time.

Normalized Urinary Flow at Puberty after Tubularized Incised Plate Urethroplasty for Hypospadias in Childhood

PURPOSE

An obstructive urinary flow pattern is frequently seen after tubularized incised plate urethroplasty for hypospadias. However, the significance of this finding has not been determined and long-term results are few. We describe postoperative long-term uroflowmetry results after puberty in males who underwent tubularized incised plate urethroplasty in childhood.

MATERIALS AND METHODS

A total of 126 boys underwent tubularized incised plate urethroplasty for distal penile to mid shaft hypospadias at Queen Silvia Children's Hospital in Gothenburg between 1999 and 2003. Of the patients 48 were toilet trained at surgery. We report on 40 patients who had data available at 2 and 12 months postoperatively, 7 years postoperatively and at puberty (median age 15.0 years, range 13.7 to 17.1). Of the patients 31 had distal and 9 had mid penile hypospadias. Clinical examination, urinary medical history, uroflowmetry and ultrasound measuring residual urine were performed. Maximum urinary flow was correlated to age and voided volume, using Miskolc nomograms for comparison of percentiles.

RESULTS

At 1 year postoperatively 15 boys (37.5%) had normal urinary flow (above 25th percentile), compared to 16 (40%) at 7 years and 38 (95%) at puberty (p <0.0001). Improvement was significant in patients with distal (p <0.0001) and mid penile hypospadias (p = 0.008), as well as in patients who did (p = 0.0078) and did not undergo intervention (p <0.0001). During followup 5 patients underwent meatotomy due to obstructive symptoms and 4 underwent dilation. Three of these 9 patients had lichen sclerosus.

CONCLUSIONS

There is great potential for normalization of urinary flow at puberty for boys with hypospadias treated with tubularized incised plate urethroplasty. Unless symptoms occur, a conservative approach seems preferable.

Long-term followup of men born with hypospadias: urological and cosmetic results

PURPOSE

We present data on long-term functional and cosmetic results after hypospadias surgery.

MATERIALS AND METHODS

Males older than 18 years with hypospadias treated in Sweden were asked to participate in the study, as well as age matched controls and circumcised men. All participants answered questionnaires, and a subgroup was examined during an outpatient visit. Relationships with outcome were analyzed using analysis of variance and regression analysis.

RESULTS

A total of 167 patients with a mean age of 34 years and 169 controls with a mean age of 33 years answered the questionnaire. Of the patients 63% had distal, 24% mid and 13% proximal hypospadias. A total of 46 patients and 49 controls presented for physical examination. Patients were significantly less satisfied with the penile cosmetic outcome regarding all parameters of the Penile Perception Score. There was a difference in penile length between patients and controls (mean 9.7 vs 11.6 cm, p <0.001). More patients than controls reported voiding dysfunction symptoms (p = 0.003). Patients had a lower maximum urinary flow rate than controls (p = 0.001). These differences were most prominent between patients with proximal hypospadias and controls.

CONCLUSIONS

Men operated on for hypospadias were less satisfied with the cosmetic result than controls, and had a shorter penile length. Patients presented with more symptoms of voiding dysfunction and displayed a lower maximum urinary flow rate. Patients with proximal hypospadias were more affected than those with milder hypospadias. Our results indicate that patients with hypospadias can be subgrouped and that those with severe phenotypes should be followed more closely during childhood as well as later in adulthood.

Importance of urinary flow studies after hypospadias repair: a systematic review

A systematic review was performed of publications relating to the results of urinary flow studies after hypospadias repair dating back to 1978, when what appears to be the first publication on this topic was found. The literature search was performed using the key words "hypospadias" combined with "urinary flow", "urine flow", "uroflow", "uroflowmetry", and "long-term". We also reviewed the abstracts and full-length articles cited in the reference list of selected articles. Criteria for inclusion in the present systematic review included descriptions of patient selection, surgical technique, the severity of disease (proximal vs distal), and the method used to determine uroflow, as well as a definition of urethral obstruction. In all, 339 article titles were found. Of these, 25 abstracts appeared relevant and the full text of these articles were reviewed, with 22 of the papers included in this review. Sixteen reports had appeared in the literature since 2001, compared with six between 1978 and 2000, suggesting an increasing interest in this topic. On the basis of the results of the present systematic review, we recommend that asymptomatic children operated on for hypospadias in infancy should have one flow study after toilet training, with that study repeated if the results are abnormal. It appears that early abnormal flows improve spontaneously, so that children operated on after toilet training who are asymptomatic should undergo their first uroflow measurement 1 year after surgery. Children with obstructed flow parameters or borderline flows should be followed until adulthood, until long-term follow up studies clarify the significance of abnormal flow parameters. Given the present findings, we anticipate that in the next two decades urologists will need to treat a number of men with strictures resulting from hypospadias repairs performed in childhood.

Urinary flow patterns in infants with distal hypospadias

OBJECTIVE

To investigate preoperative urinary flow patterns in hypospadic infants and compare them to those from normal infant boys.

PATIENTS AND METHODS

Twenty-one boys (median age 14.0, range 12.8-21.6 months) referred for distal hypospadias surgery were compared to 19 healthy boys (median age 12.0, 9.2-19.8 months). In both groups a 14-mm transit-time ultrasound flow probe mounted around the base of the penis continuously registered uroflow.

RESULTS

Median maximum flow rate (Q(max)) was significantly lower in hypospadics (2.4 vs 4.4 ml/s, P < 0.01) while there was no difference in the voided volume per micturition (19.0 vs 21.0 ml, P 0.33). Flow curve pattern analysis revealed plateau-shaped curves in 31% of hypospadics compared to none in normal infant boys. Interestingly, dyscoordinated flow curves (interrupted, staccato, spike-dome) were less common in the hypospadics (36% vs 64%, P < 0.01). Meatal size did not correlate to Q(max) (rho = 0.26, P = 0.26).

CONCLUSIONS

Infants with hypospadias void with a lower Q(max) and a lesser degree of dyscoordination as compared to normal infant boys. It can be speculated that decreased urethral compliance may contribute to the lower Q(max) and may act as a silencer for dyscoordination.

Hypospadias repair with tubularized incised plate: Does the obstructive flow pattern resolve spontaneously?

OBJECTIVE

The aim of this prospective study was to evaluate whether urinary flow improves with time after tubularized incised plate (TIP) repair.

PATIENTS AND METHOD

Between 1999 and 2003, primary TIP was performed in 126 boys. In patients old enough (48 boys, mean age at surgery 46 months, range 18-103), uroflowmetry was performed 1 year and 7 (median, range 3-10) years post surgery. Miskolc nomograms were used to compare results from the two follow ups (Q(max) in relation to voided volume and age).

RESULTS

Eleven boys had symptoms of obstruction resulting in intervention. For the other 37 boys, the mean Q(max) was 13.6 ± 5.6 ml/s 1 year postoperatively (mean voided volume 107 ± 43 ml) and 49% had flows below the 5th percentile. Seven years postoperatively the mean Q(max) was 19.0 ± 8.1 ml/s (mean voided volume 235 ± 112 ml) and 32% had flows below the 5th percentile. In the group with flows below the 5th percentile at 1 year, all improved and 28% improved to above the 25th percentile. Proximal hypospadias was more often associated with obstructive flow than distal (75%/75% compared to 43%/21% 1/7 years postoperatively).

CONCLUSION

We found spontaneous improvement (P = 0.00022) 7 years after TIP repair, although many boys still had a Q(max) in the low normal or obstructive range.

Urethral ultrasound as a screening tool for stricture recurrence after oral mucosa graft urethroplasty

OBJECTIVE

To evaluate the efficacy of sonourethrography (SUG) in combination with voiding pattern analysis to determine success after oral mucosa graft (OMG) urethroplasty. OMG urethroplasty is a standard treatment for men with recurrent urethral stricture. Because of its performance, the optimum follow-up algorithm remains controversial.

MATERIAL AND METHODS

Forty-nine patients (mean age 51 years) who underwent OMG urethroplasty were retrospectively identified. All men were subjected to a validated voiding questionnaire (International Prostate Symptom Score [IPSS]), SUG, uroflowmetry, and residual urine measurement. The predictive value was analyzed with regard to stricture recurrence or patency as well as to urethral diameter. Retrograde urethrography was done to confirm the diagnosis.

RESULTS

Strictures were bulbar in 39, penile in 4, and combined in 6 patients. Mean stricture length was 3.8 cm (range 1-10). Mean follow-up after surgery was 35 (range 15-70) months. SUG showed a mean diameter of 7.6 mm for bulbar grafts and 4.6 mm for penile grafts. Stricture recurrence was seen in 4 (8%) patients, yielding a significantly lower urethral width of 2.3 mm (P<.005). Retrograde urethrography confirmed the patency status in all. The average maximum flow rate after successful repair was 36.6 mL/s, whereas those with recurrent strictures showed rates of 11.2 (P<.03). Similar results were achieved for residual urine (P<.05). IPSS values increased from 5.1 to 12.5 in patients with recurrence (P<.01).

CONCLUSION

An algorithm consisting of SUG, uroflowmetry, residual urine and IPSS assessment reliably identifies stricture recurrence. Routine retrograde urethrography may therefore be unnecessary in the follow-up of OMG urethroplasty.