Evaluation of tunneled tunica vaginalis flap (TVF) used as adjunct in the repair of urethrocutaneous fistula post tubularized incised plate urethroplasty (TIP) technique

Evaluation of tunneled tunica vaginalis flap (TVF) used as adjunct in the repair of urethrocutaneous fistula post tubularized incised plate urethroplasty (TIP) technique

M Khalifa, MD; I Tantawy, MD; Amera H Waly, MD; Salah M Abdelaal MD

Department of Pediatric Surgery, Zagazig University Hospital, Egypt.

Abstract

Background and  purpose: Urethrocutaneous fistula (UCF) remains the  most  frequent encountered complication of hypospadius surgery even in experienced surgical  hands. The key measure to ensure a successful repair  is separation of the suture  lines in the urethra  and skin, using well vascularized elastic tissue. This study aims to use tunneled  tunica vaginalis flap(IVF) as adjunct in UCF  repair  either  initial or recurrent following TIP technique and  to evaluate outcome of cases regarding recurrence of  fistula and  other  postoperative complications.

Material and methods: In period between Jun. 2007 to Jun.2009, 14 cases of urethrocutaneous fistula  post TIP  technique with a mean age 5.6 year (3-11)  were  operated on using TVF. For each  patient, we reported original preoperative location of urethral meatus, the number and location of fistulas, number of surgery, size of fistula and duration of surgery. Outcome  of cases regarding to recurrence of fistula  and other complications was reported. Follow up of cases ranged.from 6 months to 24 months (mean  12 months).

Result: Of total  14 patients, 5 (35.7%) patients had previous attempt for closure of UCF ranged.from 1-2 times. 4 (28.6%) patients had multiple UCF ranged.from 2-3 fistulae at different location. Site of  UCF  was maximally located  proximal penile  followed by midpenile. Size of UCF ranged .from 2 to 10mm  .Operative time ranged from 45 to 90 minutes with a mean time (60) minutes.Duringfollow up period no delayed postoperative complications had been observed.

Conclusion: The  tunneled tunica  vaginalis flap is an excellent method  for closure of both initial and recurrent urethrocutaneous fistula post TIP technique. The flap is easy to be harvested and mobilized without  testicular complication and provide sufficient length to cover repaired UCF regardless of number, location  and size of fistula.

Key words: Hypospadius surgery, tubularized incised plate urethroplasty, urethrocutaneous fistula, tunica vagina/is flap.

Introduction:

Hypospadias surgery has evolved with more than 150 procedures described for surgical correction of a single  anomaly) The  most significant recent advance in surgical technique occurred in 1994 with Snodgrass' description of  the   tubularized incised  plate (TIP)

urethroplasty technique.2 Despite these advances in urethroplasty technique, a review of TIP urethroplasty reveals a combined UCF rate of2.4% across several major centers study. The majority of fistulas occurred at the junction of   the   neourethra  with  the   urethra.3

Surgery for urethrocutaneous fistulas has remained a challenge for the treating surgeons and several  surgical procedures have  been

described each claiming good results. Factors that may affect results of UCF repair may be the conditions of local tissue, duration of time after hypospadias repair, the number, location and size of the fistula, use of magnification, patient's age, previous fistula repairs and also the type of suture material used, skill of the operating surgeon and proper inversion of the edges etc.  The  key  measure to  ensure a successful  repair is separation of the suture lines  in the  urethra and  skin,  using well vascularized elastic tissue.4

In the conventional simple repair of urethrocutaneous fistulae, three layers of tissue are mobilized (margins of urethrocutaneous fistula, Dartos/surrounding tissue, skin) and

closed using fine absorbable sutures, However, this  can  be difficult  to achieve  a well­ vascularized tissuesamenable to interposition.s One possibility for interposition graft for UCF repair is the use of tunneled TVF. Unlike dissection of Dartos layer which can damage blood supply of overlying skin with impaired wound healing, tunica vaginalisbrings vascular supply from outside source hence helping in healing  of  suture  line  of  UCF  repair.6

Material and method:

In peroid between Jun. 2007 to Jun. 2009,

14 cases of urethrocutaneous fistula post TIP technique were admitted at our pedaitric surgical unit for repair of UCF (9 initial and

5 recurrent) with at least 6-month period between the previous surgery and UCF repair

for achievement of healing. Age of patients ranged from 3 to 11years with a mean age of (5.6year).

For each patient, we reported original preoperative location of urethral meatus, the number and location of fistulas, number of

surgery, size of fistula, duration of surgery, length of follow up and postoperative complications including wound infection, scrotal hematoma, testicular tethering, penile torsion or recurrence of fistulae.

In all 14 cases tunneled tunica vaginalis

flap was used as adjunct in UCF repair. Outcome of cases regarding recurrence of fistula and other complications was reported.

Figure (1):Closureof multiple urethroctaneous fistula, one penoscrotal, one distal penile and one subcoronal.

Follow up of cases ranged from 6 months to 24 months with a mean of (12  months). Operative tec:hnique:

All patients were operated on under general

anesthesia. Urethral calibration was done to exclude distal obstruction. Dilute povidone solution was injected through the meatus to visualize exact location and number of fistula. Circumferential skinincision was done around UCF and skin was mobilized and undermined to expose fistula. In case of multiple UCF at different location proximal and distal, penile skin degloving with careful dissection was performed. UCF1ract was excised and urethra was closed in two layer using 6/0 vicryl sutures over catheter Figure(!). All repairs were checked for water tight anastomosis by injecting saline into the urethra bysyring through meatus. Small incision 1-2  em was done high in the anterior  wall of hemiscrotum and scrotal attachment was dissected from tunica vaginalis. Testis was delivered from scrotal incision. The TVF was harvested on vascular pedicle and separated from testicle and cord Figure(2). The length of flap is adjusted according to the distance from harvested site to UCF site.The TVF is then tunneled underneath the penile skin Flgures(3,4). The TVF is then fixed at each UCF site using 6/0 vicryl Figure(5). Scrotal incision was closed without drain after reduction of testicle inits place and penile skin incision was closed to complete procedure Figure(6). Urinary catheter was faxed for 7-

10 days.

Figure(2):TheTVFwas harvested on vascular pedicle and separated from testis and cord.

Figures (3) and (4): The TVF is tunneled underneath the penile skin

Figure(5):Fixation of tunica vagina/is flap.

Figure(6):Closureof penile and scrotal incision and final appearance of technique.

Table (1): Types of hypospadius.

Table (2): Site ofUCF.

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Discussion:

Among the different surgical procedures advocated in hypospadias repair, urethrocutaneous fistula  remains the  most frequent encountered complication and  a serious problem, even in experienced surgical hands.7 Many innovations have led to advances in the surgical repair ofhypospadius.4 One of the most recent modifications is the tubularized incised plate (TIP) urethroplasty described by Snodgrass in 1994,2 which has become one of the  most  commonly used   techniques in hypospadias repair.  The complication rate associated with TIP urethroplasty is 5-10%, with  the  majority of  complications being urethrocutaneous fistulae.8  Other techniques have been associated  with fistula rates up to

20%.9

Urethrocutaneous fistulae  (UCF) usually result  following loss of viability of tissues involved in hypospadias repair.10 Necrosis of overlying skin subcutaneous tissue leaves the neo-urethra  exposed, thus resulting in either its total or partial disruption or fistula formation. Also,  excessive backpressure due  to distal obstruction can disrupt adequately reinforced repairs of good integrity.11

The different techniques recommended in the available literature with the aim to reduce the incidence ofUCF includes: avoidance of a opposing  urethral  and skin sutures, use of fine scalpel for skin incision, minimal tissue trauma by use of fine forceps or hooks and an inverting watertight mucosal suturing.12 Better suture materials, use of magnification, dorsal subcutaneous flap and silicone catheters have all contributed  to a decrease in fistula rate.13

The role of a waterproofmg layer between the urethra and skin is well established in the prevention and repair of fistula complication in  hypospadias surgery. The  common waterproofing techniques utilize subcutaneous tissue, Dartos  fascia,  Dartos  muscle from scrotum and tunica vaginalis from the scrotum.6

Tunneled TVF, was first described in 1970 by Hosli14 and subsequently popularized  by Snow et al.15 Shankar et al.16 operated 10 cases of  recurrent UCF and limited the use of tunica vaginalis  as waterproofing layer to the third or subsequent  repair. Routh et aJ17 had used tunneled tunica vaginalis flap for 16 patients

who had failed previous UCF repair post TIP technique. In  our  study, tunneled tunica vaginalis  flap was used for both initial UCF (72.4%) and recurrent UCF (28.6%). 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.

A series of 160  patients which had undergone urethrocutaneous fistula repair after hypospadias surgery were  studied  and  the prognostic significance of the site, size, number of fistulas and  number of the  previous operations, they concluded that there was no impact of these factors on success rate.18 In this study tunneled TVF was done for all our patients  regardless site, number  and size of fistula.

A common error observed is timing of fistula repair.  Consensus and logic  in this  regard dictates a wait and see policy for at least six months of last repair to enable the scars to mature and also the oedema and indurations to subside.13  In this  study  we operated all patients  after at least six months from last operation.

The TVF is a good vascularized flap, as it

has  a different blood  supply  and does  not depend on the vascularity of penile skin, unlike the Dartos fascia.19 It has a dependable blood supply  from the cremasteric vessels and its pedicle length can safely be increased  up to the external inguinal ring.6 Dissecting the TVF is technically easy and may be done even by beginners in hypospadius surgery.19 In the present study, we did not face any difficulty in harvesting the TVF from the testis and the cord and gained  a sufficient length to cover the UCF regardless the location or number of fistula. Care must be taken while increasing pedicle length as the tissue becomes more flimsy proximally and at the  same  time inadequate pedicle length can cause tethering of the testis at a higher level compared to the normal side in an erect position.6 Inthis study, no case of testicular tethering occurred during the follow up period.

Muruganandham et al20 operated on 51

patients of  UCFS  by  3 different surgical technique, 21 of them had been operated using

TVF and did not report any postoperative complication regarding to recurrence of fistula, penile torsion and  no  postoperative complications were encountered in testis or scrotum. Similar results had been obtained by Routh et al17 in their series of 16 boys with previous failed  attempt  UCF repair.  In the present study, no cases of recurrence of fistula were  reported during follow up period. Immediately postoperative, there was one case who developed small scrotal haematoma which resolved spontaneously. One case had wound healing problems because of skin sloughing and wound dehiscence  at suture line but had completed healing without recurrence of fistula because of  vascular tunica vaginalis interposition  flap  acting  as   barrier.

Conclusion:

The tunneled tunica  vaginalis flap  is an excellent method for closure of both initial and recurrent urethrocutaneous fistula  post TIP technique.The flap is easy to be harvested and mobilized without testicular complication and provides  sufficient length to cover repaired UCF regardless of number, location and size of fistula.

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