Management of urethrocutaneous fistula after hypospadias surgery - An experience of thirty-five cases.

INTRODUCTION: The commonest complication following hypospadias repair is occurrence of urethrocutaneous fistula. The smaller fistulas (<2 mm) are easier to close with a simple closure whereas larger ones (>2 mm) with good vascular surrounding skin require a local skin flap closure for avoiding overlapping suture lines. For the recurrent/larger fistulas with impaired local surrounding skin - incidence of recurrence is significantly reduced by providing a waterproofing interposition layer. AIMS: To study the effect of size, location, number of fistulas and surrounding tissues in selecting the procedure and its outcome. To identify various factors involved in the recurrence and to formulate a management in the cases where recurrence has occurred. PATIENTS AND METHODS: This study of 35 cases of urethrocutaneous fistula repair was done from July 2006 to May 2009 to achieve better results in fistula management following hypospadias surgery. STATISTICAL ANALYSIS USED: X(2) test and Fisher's exact test.
RESULTS: The overall success rate for fistula repair at first attempt was 89% with success rates for simple closure, layered closure and closure with waterproofing layer being 77%,89% and 100%, respectively. The second attempt success rate at fistula repair for simple closure and closure with waterproofing layer were 33% and 100%, respectively. At third attempt the two recurrent fistulas were managed by simple closure with a waterproofing interposition layer with no recurrence. All the waterproofing procedures in this study had a success rate of 100%.
CONCLUSIONS: The treatment plan for a fistula must be individualized based on variables which has an effect on the outcome of repair and to an extent dictates the type of repair to be performed. The significantly improved success rates with the addition of a waterproofing layer suggests the use of this interposition layer should be done at the earliest available opportunity to prevent a reccurence rather than to reserve it for future options.

INTRODUCTION

Urethrocutaneous fistula formation is the commonest complication of hypospadias repair, with a reported incidence of 4-25%[1]. The successful repair of this lesion depends on several basic principles. Various techniques have been described for fistula repair but with disappointing results. Simple closure although, technically easy[23] bears the potential risk of overlying suture lines and recurrence rates. Different procedures[17] have been tried for repair of larger/multiple fistulas provided the local surrounding skin is vascularized and pliable. For larger/recurrent fistulas with impaired local vascularity an interposition waterproofing layer significantly reduces the recurrence rate of the fistulas[810].

PATIENTS AND METHODS

We have operated on a total of 35 patients which underwent 41 procedures for repair of 60 urethrocutaneous fistulas following hypospadias surgery. The age at fistula repair ranged between 3 and18 years (mean age 7 years). Urethral calibration was routinely done intraoperatively with a urethral sound to exclude any distal stenosis, thereafter presence, location, number of fistulas was assessed, probing every pit in the skin with the probe to avoid missing smaller fistulae under loupe magnification. In doubtful cases methylene blue was injected under pressure from the terminal portion of neourethra while a tourniquet was applied at the base of the penis to occlude the proximal urethra. The fistulas were measured with calipers in the antero-posterior length of the penis although they were ovoid in shape [Figure 1]. A catheter of suitable size was inserted into the urethra and the fistulous tract excised by circumferential incision around the fistula. If the fistulas were located adjacent to each other they were joined into a single larger fistula and then repaired. The number, size of fistulas, status of surrounding skin [Figure 2] and suture material used in repair are shown in Table 1. The location of various fistulas is mentioned in Table 2. Smaller fistulas were repaired using simple closure technique with interrupted inverting suture line with 6-0 chromic catgut or vicryl. The subcutaneous tissue flaps were closed with 5-0 chromic catgut, respectively. For a larger fistula with good surrounding skin following simple closure of fistula site, the skin was closed by a layered closure (pants over vest repair) whereas the larger multiple/recurrent fistulas with scarred surrounding skin - an additional local/distant waterproofing flap procedure was incorporated between the fistula and skin layer. Urinary diversion in the form of perurethral catheter was done in cases considering the merits of the fistula; however, it was not considered mandatory in all cases.

Figure 1

Showing measurement of fistula

Figure 2

Showing scarred surrounding skin

Table 1

Showing association of various variables with repeat fistula rates

Table 2

Showing the frequency of location of fistulas

RESULTS

In this study the majority of fistulas occurred on the day of cathether removal (83%),followed by fistula appearance within 3 days (11%) and 4-7 days (6%), respectively. The majority of patients had no evident cause of fistulation (74%) probably indicating an error in technique of repair with inadequate inversion of mucosa, inadequate layers of closure, ischaemic tissue or overlapping suture line leading to a suture line leak. The other identifiable causes were meatal stenosis (9%), urethral stricture (10%) and suture line dehiscence (7%). On analyzing the effects of different variables on successful outcome of fistula repair it is clear from Table 1 that number, size, status of surrounding skin, suture material used have a significant effect on the favourable outcome. On applying Fischers exact test for association of these variables on the outcome -P<.05 which was significant. The overall success rate of fistula repair at first attempt was 89% with success rates for simple closure, layered closure and closure with waterproofing layer being 77, 89 and 100%, respectively – which is comparable with other studies[458] [Table 3]. The second attempt success rate of fistula repair with simple closure was 33% which significantly improved to 100% when it was combined with an additional waterproofing interposition layer [Table 3]. At third attempt the two recurrent fistulas of simple closure were managed by simple closure along with waterproofing with tunica vaginalis interposition layer with no recurrences [Table 3]. Most of the recurrences occurred where vicryl was used (success rate 62%) as compared to chromic catgut (success rate 96%) [Table 1][11]. The various waterproofing procedures used in this study are listed in Table 4. The majority of waterproofing procedures performed were distant flaps [Figures 3a–d] owing to the limited availability of unscarred local tissues. Tunica vaginalis as local flap was used in two cases of penoscrotal fistula while penile dartos and scrotal dartos [Figures 4a–d] were used in distal and proximal level fistulas, respectively. Distant flaps (Tunica vaginalis) were used for all varieties of fistula ranging from coronal to penoscrotal levels [Figure 5]. All these waterproofing procedures had a success rate of 100% in our study which is comparable to other studies[489]. The majority of complications in our study were skin necrosis, repeat fistula and meatal stenosis Table 5. Apart from managing repeat fistulas, two of the six patients with skin necrosis had superficial necrosis which healed spontaneously while three cases had an additional waterproofing layer providing a barrier layer thus preventing a repeat fistula and so were managed conservatively while one with an additional waterproofing layer required refreshening and resuturing of tunica vaginalis flap along with redraping with circumferential penile skin. The two patients of meatal stenosis were managed by serial dilatations and were reassessed at frequent intervals to look for development of meatal stenosis. Thus early regular follow-up following the repair should be done to look for impending distal obstruction and timely intervention to prevent recurrence of the fistula.

Table 3

Showing success rates at various attempts

Table 4

Various water proofing procedures used in our study

Figure 3a

Showing preoperative micturition

Figure 3d

Showing postop micturition

Figure 4a

Showing preop proximal penile fistula

Figure 4d

Showing post-op micturition

Figure 5

Showing distal reach of tunica vaginalis

Table 5

Showing postoperative complications

Showing intraop tunica vaginalis flap elevation

Showing tunica vaginalis flap suturing

Showing scrotal dartos elevation

Showing scrotal dartos elevation

DISCUSSION

The incidence of fistula can be used to judge the success of hypospadias surgery ranging from 0 to 23%[581012] which in our study is 21% being comparable to other studies.

The cause of fistula remains less known although it is likely that local infection, local ischaemia, inadequate procedure, poor tissue handling, distal obstruction due to distal stenosis or encrustration with severity of hypospadias has significant impact on the outcome of the primary hypospadias repair. On studying the effects and association of variables like size, location, number of fistulas, amount and status of available local penile skin, suture material used on the outcome of the repair-the P-value was <0.05 which was significant (Applying Fischer's exact test). However, recurrence did not relate to other variables.

The results underline that both simple closure and layered closure of a fistula at first attempt have a comparatively lower success rates[14512].

Why some fistulas recur is uncertain. Beyond any deficiencies of surgical technique or postoperative management there is no clear answer, other than that impaired local vascularity-scarred surrounding skin [Figure 2] might be the plausible explaination.

The success rates at second and third attempts were appreciably lower in which simple closure[4510] was attempted alone ranging from 50% to 80% whereas no recurrence was seen in which simple closure with additional waterproofing layer was incorporated. This further proves our point that repair with the same procedure in a locally scarred fistula leads to increased chances of recurrence and any of the waterproofing procedures should be combined to prevent further recurrence.

Shankar et al.[10] in his study of 10 cases of refistulas at second attempt found 50% success rates at third, fourth and fifth attempts but without any waterproofing layer. He limited the use of Tunica vaginalis as a waterproofing layer to third or subsequent repairs. Thus it is clear that with subsequent attempts at fistula repair, the chances of recurrence increases with decrease in success rates owing to the further scarring of the already deficient compromised surrounding skin. In our experience the use of Tunica vaginalis or scrotal dartos tissue in a scarred area as a waterproofing cover at the earliest opportunity decreases the recurrence rate coupled with the fact that the fistulas are small, easily manageable and more importantly reduce the psychological trauma of undergoing repeated surgeries by the patient.

The use of magnification, absorbable suture material and delicate tissue handling are also a must for a favourable result.

CONCLUSIONS

The treatment plan for a fistula must be individualized according to the size, location and number of fistulas with due attention to the local surrounding skin which all have an effect on the outcome of repair and to an extent dictates the type of repair to be performed. The minimum time interval of 6 months between any two procedures should be considered for a favourable outcome. The significantly improved success rates in the repair at the first, second and third attempts with the addition of a waterproofing layer suggests the use of this interposition layer should be done at the earliest available opportunity to prevent a reccurence rather than to reserve it for future occasions.