Soft tissue covers in hypospadias surgery: Is tunica vaginalis better than dartos flap?

Sir,

We read with interest the paper by Dhua et al.[1] on the comparison between dartos flap and tunica vaginalis (TVF) for soft-tissue cover after Snodgrass (TIP) hypospadias repair. Most of their cases were distal or midpenile hypospadias. The authors concluded that TVF may be better than dartos flap as a soft tissue cover for primary hypospadias repair. We offer the following comments.

The authors compared the results of single-stage TIP hypospadias repair in children receiving TVF cover versus historical controls that received dartos fascia cover operated previously by the senior author. There is one major fallacy in such a study. It is well known that the results of any operation (especially an operation like hypospadias repair) improve as the surgeon gains more experience with the operation. Horowitz and Salzhauer demonstrated a definite learning curve in hypospadias surgery.[2] They prospectively analyzed the results of hypospadias surgery performed by a single surgeon over a 5-year period. They found that the results improved throughout the 5 years, and the absolute reduction in fistula rates between the first 2 and the last 2 years was 12.7% (P < 0.02; Chi-squared). Thus, in Dhua et al's report, the seemingly better results with TVF can simply be attributed to increasing surgeon experience and the learning curve rather than any advantage with the use of TVF. However, it must be noted that even with better surgeon experience, the better results with TVF did not reach statistical significance. Hence the conclusion of Dhua et al's article should ideally be that TVF has no added advantage over the dartos flap in primary hypospadias repair.

In general, the results of single-stage TIP repair with dartos flap cover are excellent, so there is no need to use a TVF in primary TIP repair. In a series of 110 boys undergoing TIP repair for distal hypospadias with dartos cover, Jayanthi[3] reported a complication rate of 1%. Cheng et al.[4] reported a large multicentric series of 514 TIP repairs with dartos fascia cover. In their series, there were no fistulas in the 414 distal cases, while in the 100 proximal cases, there was a mere 4% complication rate.

In primary TIP urethroplasty, the dorsal subcutaneous (dartos) fascia is intact, abundant, easy to mobilize, and can cover the neourethral suture line even down to the penoscrotal junction. Thus, it should be the logical choice for neourethral cover after primary TIP repair. Another very useful additional cover for the neourethra is corpus spongiosum. When mobilized on both sides of the urethral plate and sutured in the midline, it can provide additional protection for the neourethra. Our personal experience with its use as an adjunct for TIP urethroplasty has been very gratifying, and spongioplasty can be combined with dartos flap cover for additional protection.

Separating the processus vaginalis (TVF) from the spermatic cord is not without complications, especially in a small child. For example, both the vas and testicular vessels are at risk of injury during inguinal hernia repairs in children.[5] Is it reasonable to expose a child with virgin anterior hypospadias to this risk, however low it may be, when alternative, reliable, safe and time-tested techniques are available?

In conclusion, we feel that the routine use of TVF in primary hypospadias repairs should be discouraged. However, TVF might have a role in redo hypospadias repairs where dartos tissue may be unavailable.