Snodgrass procedure for distal penile and mid-shaft hypospadias repair in children

Introduction

Hypospadias is one of the most frequent penile malformations in boys. According to some data, the occurrence rate of hypospadias varies within 1:150 – 1:250 in neonate boys [1][2]. There are several forms of this pathology: distal hypospadias, stem, and proximal forms. There are different approaches to the choice of technique and stages of surgical correction [3][4]. Surgical treatment for this malformation is the achievement of good functional and cosmetic results, which in turn, favorably affects the psychoemotional development of a boy in the adolescent and adult age [5]. Presently, a variety of methods are proposed for surgical correction of hypospadias. However, the issue of postoperative complications remains cute and widely discussed [6][7]. The most frequent complications include neourethral fistula, artefactual urethral stricture, suture failure, and operative wound infection. Some authors report that the rate of complications can be very high and reach 60% [8][9]. Snodgrass proposed the method of Tubularized Incised Plate (TIP), which became popular [10]. During the past two decades, there were lots of publications on the experience of application of this approach and its modification that involves the insertion of the foreskin free graft in the area of the incised plate, which is called Grafted Tubularized Incised Plate (GTIP) [11].

The study aimed to compare the efficiency and safety of TIP and GTIP methods performed in the clinic during the past 10 years.

Materials and methods

From 2010 to 2020, a total of 114 boys aged 6 months to 15 years old had TIP surgery at the surgical department of the Sochi Center of Motherhood and Childhood Protection. The mean age of patients was 40.9 ± 43.1 months old. The patients included 27 (23.7%) boys up to 1 year old, 57 (50%) aged 1–3 years old, 19 (16.7%) patients aged 4–7 years, and 14 (12.3%) patients aged 8–14 years old. Primary repair was made in 112 cases (98.2%), the second procedure was made in 2 (1.8%) cases. The shape of hypospadias was identified by the localization of the misplaced meatus. Distal forms of hypospadias included head, coronary, and shaft types. Mid-shaft forms of hypospadias included cases with the localization of the meatus in the mid-third of the shaft. Distal hypospadias was observed in 94 (82.5%) children, mid-shaft form was diagnosed in 20 (17.5%) children. Sixty-six children underwent a Tubularised incised plate (TIP), proposed by Snodgrass. Later, when the methods of Grafted tubularized incised plate with an internal foreskin flap were implemented in practice, GTIP-urethroplasty was made in 48 cases. The analysis of the complications included the cases of IIIb degree by the classification of Clavien-Dindo.

Surgery protocol. The surgery was performed in patients that received general anesthesia and conductive penile blockade with 0.375% of ropivacaine. The patients were placed in a supine position. The skin was incised 2 mm proximal to the meatus with a flap dissection of the urethral plate from the meatus to the top of the head. The next stage included a circular skin incision along the coronal sulcus. The penile skin was mobilized to the base. The physiological solution was injected into the cavernous bodies to provoke an artificial erection for the diagnosis of penile curvature. After that, a midline incision of the urethral plate was made from the meatus to the top of the head. To make a transsection of the meatal intersection, the incision continued 2–3 mm proximal to the meatus. In the case of GTIP, an internal foreskin flap graft of the respective size was fixed to the ventral surface of the urethra with single monofilament absorbable sutures 6/0). The artefactual urethra was formed on a Nelaton catheter with continuous suture using monofilament absorbable suturing material 6/0. The suturing started in the proximal end and finished at 6 o’clock of the neomeatus in the point where guiding loop sutures were placed. The sutures were placed so that the catheter could freely move in the neomeatus and there was no tension around the edges of the neomeatus. Further, the second row of single loop sutures was placed on the neourethra with the same suturing material.

The next stage of the surgery included suturing of the split head over the formed artefactual urethra with single loop sutures with absorbable suturing material 6/0. The excess of the foreskin was excised circularly. On the ventral surface of the head and around it, the wound was closed with single loop sutures with absorbable suturing material 6/0.

In all cases, polydioxanone (PDS) 6/0 suturing material with a needle no.13 and 0.33 mm diameter was used. Urine diversion was made via a transurethral Nelaton catheter 8 Fr installed in the bladder for 7 – 10 days. Wound healing atraumatic ointment dressing and elastic cohesive bandage were placed. After the surgery, the children were not fixed. Two diapers were put on a child with a urinary catheter between them. All patients obtained one antibacterial drug parenterally (III generation cephalosporine) to prevent infection.

Statistical analysis. The statistical analysis and processing of the data were performed using «Statistica 12.0» software (StatSoft, Inc, Tulsa, CA, USA). The normality of the distribution was checked by the Shapiro-Wilk and Kolmogorov-Smirnov tests. The coefficients of asymmetry and sampling excess were also calculated. The methods of descriptive statistics included minimal, maximal, and mean values, median, and quartile range [Q1; Q3]. Since a normal distribution was not revealed in the samplings, the data were compared using the Mann-Whitney test. In those cases when the studied feature had qualitative changes (different complications), Pearson’s χ2 test and Fisher’s test were used.

Results

The comparability of both groups was established using the Mann-Whitney test (U = 1490.5; p = 0.630; p > 0.05), which did not reveal any statistically significant differences in age between the groups (Fig. 1).

There were no intraoperative complications observed. Children had follow-up examinations 3 and 12 months after the surgery. The surgeons paid attention to the expression of cicatricial alteration of the shaft skin, location of the meatus, and quality of the urination. Postoperative complications after urethroplasty were observed in 27 (23.7%) children. In 13 (11.4%) children, urethral fistulas developed that were closed surgically 6 months after. Two (1.8%) children had expressed meatostenosis that required meatal plastic surgery. The repeated reconstruction of the neourethra was performed for suture failure in 10 (8.8%) patients. In two (1.8%) cases, secondary penile curvature developed that needed repeated surgical intervention. Good esthetic and functional results were obtained in all children. Unfavorable outcomes of the surgeries in the compared groups are presented in Table 1.

The analysis of the complications showed that fistulas prevailed in the group of patients that underwent TIP plasty. Besides, there was a high rate of suture failure on the neourethra in the group of patients that underwent foreskin flap grafting. The statistical analysis of the obtained data sowed did not reveal any significant associations between the applied surgical technique and a postoperative complication.

Discussion

Despite the development of medical technologies, surgical treatment for hypospadias is still associated with the risk of postoperative complications. TIP approach proposed by Snodgrass in 1994 because popular in the treatment for distal hypospadias due to its relative simplicity and good cosmetic results [12]. From the time of publication of this methods description, a large number of articles were published on the results of its application in the world. Pfistermuller et al analyzed 49 publications that included 4675 patients. All patients underwent TIP urethroplasty. The analysis of the data showed that the rates of fistulas and repeated surgeries after secondary interventions were higher (15.5% and 23.3%, respectively) than after primary surgeries for proximal (10.3% and 12.2%) and distal (5.7% and 4.5%) hypospadias. The application of modifications in this surgical technique decreases the risk of the formation of fistulas from 10.3% to 3.3% and the risk of repeated surgical interventions – from 13.6% to 2.8%. Besides, the analysis of the complications by the geographical location revealed differences only in the rate of meatostenosis: Northern America – 1.8%, Europe – 3.4%, the rest countries – 8.2% [13].

Mousavi et al studies publications dedicated to the application of TIP during repeated urethroplasty. The mean rate of complications after repeated surgeries reached 21.8% according to the performed analysis. Urethral fistulas had the highest occurrence rate [14].

The insertion of a graft in the incised urethral plate is the most frequent modification of the Snodgrass approach. Helmy et al performed a comparative analysis of TIP and GTIP approaches in patients with distal hypospadias. They did not reveal any statistically significant difference in the outcome of the surgical treatment in children within a follow-up year. The only significant difference was an elongation of the time of surgical intervention during GTIP [15].

Ahmed et al found the location of the meatus to be unideal after the application of the classic approach described by Snodgrass. As a result, they started to apply an internal leaf foreskin flap graft for the insertion into the incised urethral plate to form the neourethra and neomeatus. To cover the neourethra, the authors used a mobilized flap of the tunica carnea on a feeding pedicle. As a result, the authors obtained 96.1% of perfect cosmetic results. Fistulas were observed in 3.9% of cases [16].

Ferro et al. used their practical experience of TIF urethroplasty to establish anatomical predispositions for inserting the graft into the incised urethral plate. The authors’ indications included small penile head size, flat urethral sulcus, and a long dysplastic defect of the spongy body. Besides, the authors consider GTIP to be the method of choice for patients that require secondary surgeries [17].

In 2010, Rudin et al. performed a comparative analysis of TIP and TIP+INLAY graft foreskin flap insertion around the incised urethral plate and reported a lower rate of complications after the application of a graft. Urethral fistulas were observed in five (5.1%) children (that underwent multiple surgeries). There were no signs of urethral stenosis revealed. According to the authors, the GTIP method allowed the surgeons to perform a one-step urethroplasty even in patients with a small penile head, which can reduce the rate of postoperative complications significantly [18].

The analysis of the data obtained in the present study did not reveal any significant difference in the development of postoperative complications after the application of these two approaches in children with distal and shaft hypospadias. Thus, a decision on the application of any of these techniques should be made based on certain indications such as penile head size, the width of the urethral plate, the form of hypospadias, and urethroplasty in the anamnesis, which required a detailed study of the issue.

Conclusion

The analysis of a 10-year application of TIP urethroplasty and its modified version GTIP did not reveal any significant differences in the general rate of postoperative complications. However, the application of the TIP technique was associated with a higher rate of fistulas and GTIP – with a higher rate of a penile head split. The obtained data suggest the need for a selective approach to the formation of indications for TIP and GTIP and further studies on the search of criteria for the selection of patients.