Onlay island flap urethroplasty: a comparative analysis of primary versus reoperative cases
Article Outline
Abstract
Objectives
To compare the outcome of the onlay technique in cases with an untouched urethral plate (group 1) and patients who had undergone previous hypospadias repairs (group 2).
Methods
The records of the 50 patients undergoing onlay island flap urethroplasty in the past 10 years were reviewed. The frequency of fistula formation in both groups was compared using the appropriate statistical methods.
Results
Seventeen and 33 patients were enrolled into groups 1 and 2, respectively. No statistically significant difference in patient age was present between the two groups (P >0.05). Flap necrosis in 2 patients and skin necrosis in 1 patient were encountered in group 2, with the meatus located at the penoscrotal region. Ischemic skin changes occurred in one primary patient with a mid-penile meatus. Urethrocutaneous fistula occurred in 2 (11.7%) of 17 primary cases and in 14 (42.4%) of 33 cases with multiple previous operations (Pearson chi-square test, P <0.05). A fistula rate of 61.5% was recorded in group 2 when the urethral meatus was located at the penoscrotal region. After withdrawal of the cases with penoscrotal meatus, the incidence of urethrocutaneous fistula was 6.7% (1 of 15) and 30% (6 of 20) in groups 1 and 2, respectively.
Conclusions
Multiple previous operations affected the outcome of repair with the transverse onlay preputial flap, particularly in cases with a penoscrotal meatus. Repeat hypospadias repairs are more prone to complications.
Baskin et al.1 noted that extensive vascular sinuses exist in the hypospadiac penis beneath the urethral plate. Because of this, the preservation of a well-developed urethral plate has increasingly been considered an important principle in hypospadias repairs, even in the presence of mild to moderate degrees of chordee.2 In the present report, we compared the outcome of the onlay procedure in patients with the primary native urethral plate and those with a distorted plate or relocated penile skin to receive the onlay flap, in respect to the meatus localization.
Material and methods
The records of 50 patients who underwent hypospadias repair with the onlay island flap in the past 10 years were retrospectively reviewed. The same surgical team had performed all operations concurrently.
Of the 50 patients, 17 underwent primary repair and 33 (66%) had undergone previous operations other than the onlay procedure at our and other institutions. Information on the previous hypospadias repairs done elsewhere could not be obtained for 12 patients. Scrotal transposition correction with chordee resection plus Thiersch urethroplasty, tubularized skin graft urethroplasty, and tubularized incised-plate urethroplasty (TIPU) had been done in 9, 2, and 10 patients, respectively. The number of prior operations was only 1 of 20 cases in patients with a mid or distal meatus. In 13 penoscrotal hypospadias, 2 and 3 operations had been done in 10 and 3 cases, respectively.
In patients with mid and distal penile hypospadias, the urethral plate was not virgin and minor to moderate degrees of scar tissue were evident. In the reoperative proximal cases, relocated skin tissue was used to receive the onlay flap. An adequate amount of preputial tissue was available in all primary and reoperative cases with the mid and distal meatus. Some part of the dorsal penile skin was used with the available preputial tissue in 5 reoperative cases with the meatus located at the penoscrotal region.
The duration from the prior failed repair to the salvage onlay procedure was at least 6 months in all cases. None of the patients had received hormonal stimulation before surgery.
The technique was similar to that described by Elder et al.3 The differences were the use of a suprapubic drainage tube and the removal of the urethral stent after 7 days. We also did not use lidocaine plus epinephrine infiltration for hemostasis. A dorsal plication was done in 2 primary cases with a penoscrotal meatus. In other cases, chordee was not present after degloving the tethering shaft skin.
Patients were divided into two groups: primary patients (group 1) and patients who had undergone previous operations (group 2). The data were analyzed using the Statistical Package for Social Sciences, version 10.0, software program.
Results
In the first group, patient age ranged from 2 to 29 years (mean 9.88 ± 7.12), and in the second group, patient age ranged from 2 to 28 years (mean 9.33 ± 5.25) at the time of onlay island flap urethroplasty. Patient age was not significantly different statistically between the two groups (P >0.05). Associated anomalies included a unilateral undescended testis in 1 patient and bilateral undescended testes in 2 patients.
Flap necrosis occurred in 2 patients and skin necrosis in 1 patient in group 2 with the meatus located at the penoscrotal region. Ischemic skin changes occurred in 1 primary patient with a mid-penile meatus. Skin necrosis resulted with fistula formation. The cosmetic outcome was acceptable in patients whose recovery was uneventful. Because long-term follow-up data are not available for all the patients, we cannot report the incidence of urethral diverticulum.
Table I summarizes the distribution of the location of the urethral meatus in groups 1 and 2. Table II presents rate of fistula formation according to the location of the urethral meatus. Statistical analysis disclosed a significant difference in the rate of fistula formation according to location (Pearson chi-square test, P = 0.02).
TABLE I. Distribution of urethral meatus by group
| Location | n | Group 1 (n) | Group 2 (n) |
|---|---|---|---|
| Distal penile | 27 | 11 | 16 |
| Mid-penile | 8 | 4 | 4 |
| Penoscrotal | 15 | 2 | 13 |
| Total | 50 | 17 | 33 |
TABLE II. Rate of fistula formation by urethral meatus location
| Location | n | Fistula Formation (%) |
|---|---|---|
| Distal penile | 27 | 5 (18) |
| Mid-penile | 8 | 2 (25) |
| Penoscrotal | 15 | 9 (60) |
Urethrocutaneous fistulas occurred in 16 (32%) of 50 patients. The fistula formation rates in groups 1 and 2 were compared using the Pearson chi-square test. Fistula occurrence in group 2 was found to be significantly greater (P = 0.028) than in group 1 (Table III).
TABLE III. Fistula formation in groups 1 and 2
| Group | n | Fistula Formation (%) |
|---|---|---|
| 1 | 17 | 2 (11.7) |
| 2 | 33 | 14 (42.4) |
After withdrawal of the 15 cases with a penoscrotal urethral meatus from the overall group, the incidence of urethrocutaneous fistula formation was 6.7% (1 of 15) and 30% (6 of 20) in groups 1 and 2, respectively. Although the rates seemed different, this difference did not reach statistical significance because of the small sample size (Fisher’s exact test, P >0.05; Table IV).
TABLE IV. Fistula formation after withdrawal of penoscrotal cases
| Group | n | Fistula Formation (%) |
|---|---|---|
| 1 | 15 | 1 (6.7) |
| 2 | 20 | 6 (30) |
Comment
A variety of surgical techniques have been described for hypospadias repair over the years.4 However, no single technique is available that can be used for the repair of various types of hypospadias. Each technique carries its own handicaps and advantages.
The onlay preputial flap was originally described as an alternative to the meatal-based flap urethroplasty for repair of anterior hypospadias.3 Although the most common procedure in most series for the distal hypospadias was the flip-flap procedure in the past,5, 6 the trend was to change to the TIPU after the description of Snodgrass7 in 1994. A well-vascularized proximal ventral skin is necessary for success of the flip-flap procedure. We used the onlay procedure in distal hypospadias with thin ventral proximal skin and after failure of the Mathieu and TIPU procedures. Although avoidance of the proximal penile shaft skin deficiency resulting from a meatal-based flap was suggested as an advantage of the onlay procedure, skin coverage has never been a serious problem in our practice with the flip-flap procedure.8 The onlay island flap technique is also applicable in patients with mid-shaft and proximal hypospadias without fibrous chordee.2, 9
In proximal cases, the onlay transverse preputial island flap is a good alternative when chordee is not present. However, mild degrees of curvature are not an absolute contraindication for the onlay island procedure, because, in some of the cases, it can be simply corrected by takedown of the penile shaft skin, which causes tethering. Because persistent curvature is commonly due to a corporeal disproportion rather than tethering, division of the urethral plate and ventral dissection of fibrous tissue do not routinely straighten the curved penis.8 Dorsolateral plication of the corporeal bodies with nonabsorbable suture can be successfully done in such cases.
However, the onlay island flap does not carry the risk of anastomotic stricture, as does tubularized flaps because of circumferential anastomosis proximally. The other advantage of the onlay island flap is the preservation of urethral plate that prevents kinking and tortuosity of the neourethra. One handicap of the onlay procedure is ischemia of the dorsal skin to cover the penile shaft after dissection of the preputial island flap with its blood vessels. A double onlay preputial flap technique was recommended for simultaneous ventral skin cover of the penile shaft, because it shares the same rich blood supply of the island flap that is used to create the neourethra.10 This well-vascularized ventral skin cover may eventually be used in future procedures to treat complications of the primary repair.11 In our series, 1 case with ventral skin necrosis with fistula formation resulted.
Prior surgery often leaves patients with significant scarring and a limited amount of preputial skin for secondary procedures, especially in cases with a penoscrotal meatus. In the more distal cases, scarring is much less, and many treatment alternatives, such as the secondary Mathieu procedure, salvage onlay flap repairs, and TIPU, can be performed with a fair outcome.5, 12, 13 In our practice, circumcision has never been practiced with the flip-flap and TIPU procedures; therefore, an adequate amount of preputial tissue has been available for the salvage onlay procedures.
In recent years, particular importance has been given to the preservation of the urethral plate.8 In the onlay procedure, the well-vascularized urethral plate is preserved and constitutes the dorsal wall of the neourethra. Cooper et al.14 reported that incorporation of the well-vascularized spongiosa tissue located along the sides of the urethral plate in the suture lines provides coverage and reduces fistula formation with the onlay island flap. Whether the distortion of the urethral plate by the previous operations adversely affects the outcome of the onlay preputial flap has rarely been analyzed in published studies. Simmons et al.15 analyzed the records of 36 patients who underwent salvage onlay flap repair for persistent fistula or dehiscence or stricture and reported a success rate of 93% (28 of 30) and 50% (3 of 6) in the dehiscence and stricture groups, respectively. They noted the importance of stricture as a reason for the salvage onlay procedure. Multiple procedures were needed after failed salvage onlay repair in this group. Jayanthi et al.16 also reported their results with salvage island flap procedures in 16 patients. Of the 16 procedures, 8 were tubularized and 8 were onlay repairs. They achieved a successful outcome in one stage in 7 cases (43%). However, it was not possible to determine what percentage of this success was achieved only from the onlay procedure in their report.
In our study, we recorded urethrocutaneous fistulas in 2 (11.7%) of 17 group 1 patients (primary) and 14 (42.4%) of 33 group 2 patients (multiple previous operations). This difference was statistically significant (P = 0.028). Previous extensive chordee resection and relocated skin with its poor blood supply for the flap may be the risk factors leading to a high rate of fistula formation (61.5%) in the penoscrotal group. Because only 2 patients in group 1 had a penoscrotal meatus, it was not possible to make a statistical comparison in the penoscrotal group.
After excluding the cases with a penoscrotal meatus from the overall group, we repeated the statistical analysis. The urethrocutaneous fistula rate was 6.7% (1 of 15) in the primary cases and 30% (6 of 20) in the secondary cases. Although the percentages seemed quite different, the difference was not statistically significant (P = 0.199), possibly because of the small sample size.
Conclusions
Salvage hypospadias repair with the onlay flap is a challenging procedure, particularly in patients with a penoscrotal meatus. Increasing the neovascularity with preoperative hormonal stimulation may be a useful adjunctive procedure to improve the outcome in this group.
References
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- . Double onlay preputial for proximal hypospadias repair. J Urol. 1996;156:832–834
- . The role of the Mathieu repair as a salvage procedure. Br J Urol. 1993;72:52–53
- Repair of the complications of hypospadias surgery. J Urol. 1993;150:1415–1418
- . Preservation of urethral plate spongiosum (technique to reduce hypospadias fistulas). Urology. 2001;57:351–354
- Repair of hypospadias complications using the previously utilized urethral plate. Urology. 1999;54:724–726
- Can previously relocated penile skin be successfully used for salvage hypospadias repair?. J Urol. 1994;152:740–743
PII: S0090-4295(02)02138-6
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