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Neourethral covering is an essential technique for preventing complications such as fistula and glans dehiscence in hypospadias repairs. The spongioplasty has been reported for neourethral coverage about 20 years ago. However, reports of the outcome are limited.
Objective
This study aimed to retrospectively evaluate the short-term outcome of spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty (DIGU).
Methods
From December 2019 to December 2020, 50 patients with primary hypospadias (median age at surgery, 37 months; range, 10 months–12 years) were treated by a single pediatric urologist. The patients underwent spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty in single stage. The penile length, glans width, urethral plate width and length, and the location of the meatus of the patients were recorded preoperatively. The patients were followed up,complications noted, and postoperative uroflowmetries at the one-year follow-up time were evaluated.
Results
The average width of glans was 12.92 ± 1.86 mm. A minor penile curvature was observed in all patients (≤30°). The patients were followed up for 12–24 months, and 47 patients (94%) were free from complications. A neourethra formed with a slit-like meatus at the tip of the glans, and the urinary stream was straight. Three patients had coronal fistulae (3/50) and no glans dehiscence, and the mean ± SD Qmax of postoperative uroflowmetry was 8.13 ± 3.8 ml/s.
Discussion
This study estimated the short-term outcome of the DIGU covered using spongioplasty with Buck's fascia as the second layer in patients diagnosed with primary hypospadias with a relatively small glans (average width <14 mm). However, only a few reports emphasize spongioplasty with Buck's fascia as the second layer and the DIGU procedure performed on a relatively small glans.
The major limitations of this study were its short follow-up time and the retrospective data collection.
Conclusions
Graphical AbstractIllustration of spongioplasty with Buck's fascia covering dorsal inlay graft urethroplasty.
Hypospadias is the most common malformation of external genitalia, affecting about 20.9/10000 live birth boys, with increasing international prevalence [
]. To date, surgical repair has been the only option for treatment. Although more than 300 procedures and modifications have been reported over time, hypospadias repair remains a surgical challenge for pediatric urologists because of the persistent high rates of postoperative complications [
]. Tubularized incised plate urethroplasty (TIPU) remains one of the most popular procedures for primary hypospadias. However, complications such as coronal fistula, glans dehiscence, and meatal stenosis are more commonly associated with small glans [
]. To enhance re-epithelialization and reduce the postoperative complications of meatal stenosis and coronal fistula of the classical TIPU procedure, we advocate a modified spongioplasty with Buck's fascia covering technique in combination with the dorsal inlay graft urethroplasty (DIGU), previously described by Kolon et al. [
New concepts of modern hypospadiology are continuously emerging. In addition to the urethroplasty, the use of multiple overlapping tissue layers is essential for minimizing complications [
]. Spongioplasty preserves the divergent corpus spongiosum at the two sides of the urethral plate, either by using the Y-to-I wrap of the spongiosum for neourethral reinforcement or by dissecting the internal region of spongy tissue to obtain a tension-free intermediate layer [
Multiple procedures were considered and combined for hypospadias repair, aiming to ensure better voiding function and final cosmetic outcomes with a slit-like meatus with sufficient caliber, a suitable glans fusion length [
This retrospective study aimed to evaluate the immediate outcomes of spongioplasty with Buck's fascia as coverage of the DIGU in a cohort of Chinese boys diagnosed with hypospadias at a single tertiary children's medical center.
Patients and methods
Primary distal hypospadias in 57 patients were consecutively repaired by a single pediatric urologist (Zhang T) at the Children's Hospital of Soochow University between December 2019 and December 2020. The stretched penile length, width of the glans, length and width of the urethral plate, location of the meatus at division of the corpus spongiosum, and degree of ventral penile curvature on artificial erection were recorded in the surgical notes preoperatively.
Fifty of 57 patients who received spongioplasty with Buck's fascia as the coverage of the DIGU procedures and consistently attended the postoperative follow-ups ranging between 12 and 24 months were enrolled in the retrospective study. Their ages ranged from 10 months to 12 years (median, 37 months). The complications were noted and postoperative uroflowmetries performed at the one-year follow-up appointment were evaluated. None of the patients received preoperative hormonal treatments.
Operative techniques
All procedures were performed under general anesthesia. The surgical procedure is summarized in Fig. 1. A holding suture was then placed vertically on the glans. A superficial U-shaped incision was made around the meatus, with parallel incisions on either side of the urethral plate (UP) to the mucosal collar, followed by a coronal circular incision. The penis was degloved, and a dorsal midline plication was used for orthoplasty (the 46 patients who still had 15–30° curvatures). A parallel incision was made down to the copra cavernosum on each side of the UP from the tip of the glans to the proximal division of the corpus spongiosum. The divergent corpus spongiosum was dissected with Buck's fascia on each side externally to the 3–9 o'clock position. If the corpus spongiosum contributed to the curvature, it was transected. A deep midline incision was made in the UP, a dorsal preputial graft was harvested and quilted in the incised plate, and the plate was then tubularized over a short silicone catheter (1 cm longer than the neourethral; 8–12 Fr.) in a single layer of 6/0 Vicryl running suture. The spongioplasty and glanuloplasty (Fig. 2) were performed by suturing the two sides of the corpus spongiosum to the middle line and covering the neourethral with interrupted subcuticular 6/0 Vicryl sutures. A 5 Fr. single-J stent was placed inside the silicone catheter for urine drainage, and the silicone catheter was sutured at the glans using 5/0 Prolene sutures. The patients were discharged from the hospital after removal of the single-J stent on postoperative day 7, and the short silicone catheter remained for 4 weeks.
Fig. 1Intraoperative photos: a, dissecting the divergent corpus spongiosum with Buck's fascia at each side to the 3–9 o'clock. b, incising the urethral plate. c, inlay grafting. d, tubularized urethroplasty. e, spongioplasty with Buck's fascia. f, postoperative appearance.
The Statistical Package of Social Science Software Program (SPSS) version 23.0 was used. Data are expressed as mean ± standard deviation. The data was examined for normal distribution and homogeneity of variance using the Kolmogorov–Smirnov test.
Results
Fifty primary hypospadias were treated using spongioplasty with Buck's fasciacovering DIGU procedures in a single stage, and the postoperative office visit follow-ups ranged from 12 to 24 months (median, 13.2 months). The locations of meatus were described (Table 1). The penile length, glans width, urethral plate width, and length were evaluated (Table 2).
Table 1The location of meatus: at the division of the corpus spongiosum.
Of these fifty patients, 47 patients (94%) were free from complications. A neourethra was formed with a slit-like meatus at the tip of the glans, and the urinary stream was straight. Urethrocutaneous fistula occurred in three (6%) cases. None of the patients had glans dehiscence or meatal stenosis. Postoperative uroflowmetry was performed in 50 patients, and the mean ± SD Qmax was 8.13 ± 3.8 ml/s.
Discussion
The two divergent corpus spongiosum on each side of the urethral plate are a notable morphological change [
]. However, the divergent corpus spongiosum is inconsistently hypoplastic in different cases. In some cases, they may be present as distinct pillars of healthy erectile tissue, which can be warped in a Y-to-I fashion. However, in other cases, the divergent corpus spongiosum is flat and thin [
] and can only be dissected in the internal region of the spongy tissue to obtain a tension-free intermediate layer. These conditions allowed us to dissect the divergent corpus spongiosum together with Buck's fascia in one layer for coverage, regardless of the shape of the corpus spongiosum, to ensure improved blood supply because the nerves and blood vessels diverged from the dorsal 11 and one o'clock, spreading around the cavernous bodies up to the junction of the corpus spongiosum and corpora cavernosa [
Using Buck's fascia as an integral covering in urethroplasty to restore the anatomical structure of the penis in one-stage hypospadias repair: a multicenter Chinese study comprising 1,386 surgeries.
]. However, we emphasize the spongioplasty and trying to save this erectile tissue, together with Buck's fascia, can improve the blood supply.
The hypoplastic corpus spongiosum on either side of the urethral plate may be abnormally attached and contribute to the curvature, which has historically been preferred for resection during orthoplasty. Cooper et al. [
]. Mentioned that in some cases, the development of the glans wings can correct mild distal chordees. In our cases, we saved the distal corpus spongiosum together with the glans wings and transected the corpus spongiosum at the division level. This maneuver can reduce the degree of penile curvature in certain cases.
The penis sizes varied by geography or ethnicity, which may affect the surgical outcome. According to our data, the average glans width in our preadolescent patients of the Chinese population was 12.9 mm and the average urethral plate width was 4.9 mm, which is less than the 14 mm of glans width [
]. Almost 80% of our patients had a small glans, increasing the possibilities of complications in the hypospadias repair. Therefore, improving coverage technique and better glanuloplasty are extremely important.
Neourethral coverage is essential for hypospadias repair. The most used tissue is the dartos fascia with various flaps, in the form of single-layer or multi-layer flaps [
]. Our single layer of spongiosum tissue with the Buck's fascia had a fistular rate of approximately 6%, similar to a single layer of the dartos fascia. An additional dartos fascia as a second layer to cover the neourethral in the DIGU group may prevent fistula in the penile shaft but is technically harder for the coronal region.
Furthermore, we noticed no meatal stenosis in our cases. According to Prof. Snodgrass, meatal stenosis after the TIPU procedure was diagnosed based on obstructive voiding symptoms and a calibration of <8 Fr. [
]. In our patients, the caliber of the neourethral was set at > 8 Fr., and the stenting time was prolonged to 4 weeks. [NO_PRINTED_FORM]Considering wound contraction, regular neourethral dilatation for 2–3 months was suggested to prevent urethral stricture after TIPU [
]. Additionally, in the mechanochemical model of the dermal wound healing process, after re-epithelialization, fibroblasts and myofibroblasts are involved in wound contraction for three to four weeks, and extracellular matrix (ECM) remodeling continues for several months [
]. We considered that a prolonged neourethral short stent for 4 weeks would be beneficial for wound contraction. Our patients did not complain of symptoms of obstruction, even though the Qmax of uroflowmetry was relatively low.
Urethroplasty is the most important component in hypospadias repair. A recent systematic review clarifying the current evidence did not demonstrate the superiority of DIGU over TIPU in terms of treatment success and overall complication rates; however, using an inlay graft decreased the risk of meatal/neourethral stenosis [
] used excised glans spongiosum tissue and a type of Heineke-Mikulicz closure for urethral plate enlargement and the consequent glanular neourethra with a reconstructed fossa navicularis had a straight urinary stream. According to Poiseuille's law of flow resistance, as mentioned by Braga et al. [
], a more distensible neourethra with a larger cylinder radius may decrease the resistance. In our cases, we hypothesize that the dorsal inlay graft can greatly enlarge the narrow urethral plates at the glanular level, which could reconstruct the fossa navicularis with a larger cylinder radius to reduce flow resistance.
In addition, the dorsal inlay graft is a dorsal tissue associated with better response to androgenic stimulation. As Grosos et al. [
Is it safe to solely use ventral penile tissues in hypospadias repair? Long-term outcomes of 578 Duplay urethroplasties performed in a single institution over a period of 14 years.
] mentioned, solely using the ventral tissues for urethroplasty may represent an additional risk of late failure because the ventral tissue may respond less to androgenic stimulation when this growing organ reaches puberty. However, a larger cohort found no difference in the AR expression in the ventral foreskin samples of the hypospadias cases versus controls, which lacked puberty data [
Androgen receptor expression in preputial dartos tissue correlates with physiological androgen exposure in congenital malformations of the penis and in controls.
]. Considering the surgical aspect of the urethroplasty, using the normal dorsal tissue for urethral augmentation may improve the response to androgenic stimulation later in puberty.
Owing to the traditional practice of early toilet training in Asian families [
], most Chinese parents prefer to have their baby's toilet training before one year of age and completed within the first three years. Every patient with hypospadias underwent a uroflowmetry study at the postoperative follow-up, with the youngest patient at 22-months-old. Within the short-term follow-up period, patients younger than two-years tend to have lower uroflowmetry results, whereas older patients seemed to have better uroflowmetry results with better bladder capacities. Overall, the first follow-up uroflowmetry Qmax was 8.13 ± 3.8 ml/s, while our patients were younger than those reported by Kim et al. [
Age-related changes in urinary flow following dorsal inlay graft urethroplasty for hypospadias in early childhood: potential improvement over 11 years of age.
We did not record the glans fusion length mentioned by Prof. Snodgrass until we noticed that none of our patients had a glans dehiscence. This parameter can be used as an indicator of cosmetic results in future studies.
The major limitation of our study is its retrospective design. Further randomized controlled trials of distal spongioplasty are required to confirm its effectiveness. Additionally, a single-surgeon series cannot be generalized as an outcome of repair, including complications, which may be associated with the surgeon's skillset. Furthermore, long-term follow-ups are needed for the voiding function and an esthetic penile feature using cosmetic evaluation such as the “HOPE” score. We will continue follow-ups with those patients to puberty and into adulthood for the long-term evaluations of the voiding and sexual functions.
Conclusion
Dorsal inlay graft urethroplasty combined with spongioplasty with Buck's fascia as coverage is an effective procedure. In our study, this combination had good short-term outcomes for primary hypospadias repair.
Financial support statement
This study was partially supported by grants from the Jiangsu Province for Medical Science and Clinical Technology Projects (BL2012051) and Suzhou Municipality for Science and Technology for People's Livelihood (SS201754).
Conflicts of interest
All authors declare no competing interests.
Ethical approval
Approved by the institutional ethics committee (decision number: 2022CS016).
Acknowledgments and Funding
The authors thank Mrs. Xuewei Jiang for her help sketching surgical the illustration. This study was partially supported by grants from the Jiangsu Province for Medical Science and Clinical Technology Projects (BL2012051) and Suzhou Municipality for Science and Technology for People's Livelihood (SS201754).
References
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Groisman B.
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et al.
Hypospadias prevalence and trends in international birth defect surveillance systems, 1980–2010.
Using Buck's fascia as an integral covering in urethroplasty to restore the anatomical structure of the penis in one-stage hypospadias repair: a multicenter Chinese study comprising 1,386 surgeries.
Is it safe to solely use ventral penile tissues in hypospadias repair? Long-term outcomes of 578 Duplay urethroplasties performed in a single institution over a period of 14 years.
Androgen receptor expression in preputial dartos tissue correlates with physiological androgen exposure in congenital malformations of the penis and in controls.
Age-related changes in urinary flow following dorsal inlay graft urethroplasty for hypospadias in early childhood: potential improvement over 11 years of age.
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