Introduction

Despite the advance in hypospadias repair procedures, urethrocutaneous fistula (UCF) remains one of most common complications with variable reported incidence 1. The reasons why fistula do or do not occur are not fully known. Deficiency in local growth factors in hypospadias skin might contribute to the high rate of healing complications 2. Other factors like local infection 2, local ischemia 3, poor tissue handling 4, distal obstruction and epithelial interposition between the edges of neourethra have a significant impact on repair outcome 5.

Avoidance of overlapping of urethral and skin suture lines by tissue interposition, significantly reduces fistula formation 6. Many techniques for tissue interposition have been described 7. Dartos pedicled flap8. Tunica vaginalis flap 9 and de-epithelialized penile skin flaps 10 are used frequently. Paucity of local tissue is a challenging issue in many patients, hence, extra-genital tissues (e.g. fascia lata) are alternative donors 11. In this study, we evaluated our experience in using the dermis for repairing large (≥4 mm) 12 urethrocutaneous fistulas both in graft and flap forms.

Patient and methods

Patients

Twenty five patients with urethrocutaneous fistula complicating hypospadias repair were involved in a prospective study using the dermis as a reinforcing interposing layer (from March 2015 to September 2017). Their ages ranged from 4-20 years. All the patients underwent surgical repair after at least one year from the last failed hypospadias repair procedure.

Surgical Technique

All the patients were operated upon under general anesthesia. After all the essential steps of draping and sterilization being accomplished, a stay glanular suture using 3-0 silk was applied, then urethral calibration was routinely performed intraoperatively with a urethral sound to exclude any distal stenosis. The essential marking of the proposed flap and the margins of fistula is done using methylene blue dye, then local infiltration of the area with diluted epinephrine and lidocaine 2% (1:200,000) performed to ensure bloodless field. Foleys catheter of different calibers are used to divert the urine from the repaired site (Figure 1).

A circumferential incision using No.15 blade is made around the fistula involving the skin and dartos fascia. The fistula is then closed primarily as a first layer by turning the incised margins upside down using 5/0 or 6/0 polyglycolic acid suture in a continuous subdermal manner (Figure 2).

Then the adjacent marked flap is de-epithelialized, incised, raised and turned over the repaired fistula site and fixed in place using 5/0 polyglycolic acid suture in an interrupted manner as a second reinforcing layer (Figure 3).

For those patients with paucity of local pliable tissues due to recurrent fistulas, free dermal graft was taken from medial arm or cubital flexion crease (avoiding the hairy areas) and inset over the repaired fistula site using 5/0 polyglycolic acid suture in an interrupted manner as a second reinforcing layer. The donor site is closed in one layer using polypropylene 3/0 suture in a sbcuticular manner.

Then the skin is closed by redistribution of penile and/or scrotal skin using 4/0 polyglycolic acid suture in an interrupted manner (Figure 4). Small corrugated drain was left in place to prevent any possible hematoma formation.

The area is dressed using non-adherent layer (gauze impregnated with antibiotic ointment) as a first layer then dry gauze as an absorbent second layer. Surgical plaster tape is used to maintain the dressing in place. All the patients are kept on cephalosporin antibiotic cover for 7 days (3 days parenterally and 4 days orally).

Follow up

All the patients were discharged on the first postoperative day after removing the dressing to inspect the wounds and suture lines and assess the viability of flaps.

The drain also removed and the dressing applied in the same way and changed every other day for one week, then the Foleys catheter removed and the patient is left for normal voiding with digital support of the area of repair.

Then the patients were scheduled back for regular visits at a weekly interval in the first postoperative month, then monthly for 4-5 consecutive months. In each visit the healing process was assessed, observing the suture lines closely to assess any wound dehiscence or urethrocutaneous fistula formation, also ask the parents or the patient about the stream of urine and instruct them about the frequent dilatation process using a glass probe lubricated with lidocaine gel on a daily base for at least 3 months.

Result

All the patients presented with large fistulas (>4 mm in diameter) as shown in (Table 1). Fistula site was mostly proximal-penile followed by mid-penile (Table 2). Twelve of the patients were presented with recurrent fistulas after primary hypospadias repair. For those patients treated with dermal flaps(15 patients); no postoperative complications were seen apart from one patient who developed recurrence of fistula due to wound dehiscence following local wound infection (Figure 5). All the patients(10 patients) who treated by free dermal graft had successful repair with normal urine stream.

Discussion:

During the last decade, many surgical techniques have been adopted to repaire or prevent the recurrent of UCF. All of these techniques were based on multilayered repair using tissue interposition between neourethra (first layer) and the skin to avoid suture line overlap 12. However, it is obvious that these efforts were effective in decreasing the incidence of UCF but didn^’t completely prevent it 13. In clinical practice dartos pedicled flap has the widest application as an interposing reinforcing layer 14. Similarly tunica vaginalis flap 15. Both provide additional blood supply for neourethra and promote healing. But dartos fascia is not always available in generous amount especially in those with recurrent fistulas and dermal necrosis may ensure if skin vascularity is compromised 9. The use of tunica vaginalis has also some limitations. Its proximal extent provides some difficulty to obtain long pedicle to address distal shaft fistulas and this shortage in length can provide secondary chordee. Beside that, if cremasteric fibers are included with the flap, penile torque can occur 7.

Deepitheliazed turnover flap (dermal dartos flap) was used by Ahuja to repair ten patients with UCF. Nine of them healed without complications and only one patient suffered pin point fistula that was closed spontaneousely 10.

In our series of patients, we adopted Ahuja^′s approach (dermal dartos flap as an interposing reinforcing layer) to repair fifteen patients with large UCF. Our results were promising and comparable with that of Ahuja. Fourteen patients were healed without complications and only one suffered recurrent fistula due to local wound infection. These promising result can be explained by the strength of interposing layer that is composed of composite structure, the dermis and its underlying dartos, that can be designed at any site along the penile shaft. Similar flap can also be designed to repair fistulae at scrotal area inspite of hair bearing skin because this flap is small and it is unlikely that more than 3-4 hair follicles will be buried 10. However, we prefer using tunica vaginalis as interposing layer at the scrotal region.

All of the above methods may be difficult to apply in those patients with recurrent large UCF due to paucity of local pliable tissue that is provided by scarring process 16. Hence, it is better to think of using distant extragenital tissue as an interposing layer 17. The promising results of using the dermis as free patch graft in reconstructive peyronies disease 18 encouraged us to use free dermal patch graft as an interposing reinforcing layer. We adopted this technique in ten patients with recurrent large UCF. In all of these patients, the fistulae were closed successfully. We attributed these promising results to two points: First to the generous amount of dermal graft that can cover the whole neourethra and surrounded area without any tension and second to well vascularised skin flap that covers the neourethra and dermal graft because the dartose fascia is not dissected off the skin. The need for another incision at the donor site of dermal graft seems to be the only disadvantage of this technique; however, the donor site incision is small and can be camouflaged in the cubital crease or medial arm.

Conclusion

In conclusion, dermis seems to be an acceptable and effective tissue substitute as an interposing and reinforcing layer in repairing large UCF. However, larger series of patients and longer period of fellow up are required to accurately prove these results.

Funding Support

The authors declare that they have no funding support for this study.

Conflict of Interest

The authors declare that there is no conflict of interest.