Dorsal Versus Ventral Dartos Flap to Prevent Fistula Formation in Tubularized Incised Plate Urethroplasty for Hypospadias Doğakan Yiğit1*, Dinçer Avlan2 Purpose: The purpose of this study is to evaluate the results of two different flap procedures for the prevention of urethrocutaneous fistula in hypospadias patients undergoing tubularized incised plate urethroplasty . Patients and Methods: We retrospectively reviewed 89 patients who underwent hypospadias repair. The standard technique of tubularized incised plate urethroplasty was used. There were 45 patients in Group 1 and 44 patients in Group 2, in which ventral and dorsal dartos flaps were used to cover the neourethra respectively. Surgical compli- cations were assessed as the main outcomes. The results were analyzed with Chi-square and Mann-whitney U tests. Results: There was no significant difference between the groups in terms of age and meatus location. We observed postoperative surgical complications in 15 (33.3 %) patients in Group 1 and in 4 (9.1 %) patients in Group 2. The complications noted in the Group 1 were urethrocutaneous fistula in 10 patients ( 22.2 %) and meatal stenosis in 5 patients ( 11.1 %). In Group 2, fistula was observed in 2 patients (4.6 %) and stenosis in again 2 patients (4.6 %). Urethrocutaneous fistulas occurred statistically more frequently when ventral based dartos flaps were used (P < .05). Conclusion: Several flap procedures and their modifications have been suggested to avoid fistula formation. With- in these procedures, dartos flaps are reported to be very useful for primary distal or proximal hypospadias repair and reoperations. In this study, we concluded that vascularized dorsal preputial dartos flap procedure is safe and more effective than ventral based flap in the prevention of fistula formation. Keywords: dartos flap; hypospadias; tubularized incised plate urethroplasty; urethrocutaneous fistula 1Department of Pediatric Surgery and Pediatric Urology, Health Sciences University Prof. Dr. Cemil Taşçıoğlu City Hospital, İstanbul, Turkey. 2Department Of Pediatric Surgery and Pediatric Urology, Trakya University Hospital, Edirne, Turkey. *Correspondence: Department of Pediatric Surgery and Pediatric Urology , İstanbul , Turkey. Tel : +90 212 3145500. Fax : +90 212 3145512. E-mail: dogakanyigit@gmail.com Received December 2021 & Accepted June 2022 INTRODUCTION Hypospadias is one of the most common malforma-tions of the external male genitalia and the inci- dence is about 1/200 to 1/300 of live births(1). Although, numoreous different techniques are described for hypo- spadias repair, complications, such as urethrocutaneous fistula and urethral stenosis, still remain a major prob- lem in a significant amount of patients(2). Tubularized incised plate urethroplasty (TIPU) has gained vast popularity among pediatric urologists for hypospadias repair, because of its low complication rate and better cosmetic results, especially anatomical ap- pearance of glans with slit like meatus(3). However, ure- throcutaneous fistula formation and meatal stenosis still exist as common complications, which are reported as high as 16 - 25 % and 15 - 21 % respectively(4,5,6,7). Oth- er possible complications of TIPU procedure are wound dehiscence, urethral diverticula, skin necrosis, penile necrosis, and hematoma(7). One of the most important factors in reducing fistula formation in hypospadias re- pair is the application of a protective intermediate layer between the neourethra and the skin. For this reason, several flap procedures and their modifications have been suggested to avoid fistula formation(8-12). Within these procedures, dartos flaps are reported to be very useful for primary distal or proximal hypospadias repair and the reoperations(9,11). In this study, we aimed to investigate the efficacy of dorsal preputial dartos flap and ventral dartos flap in the prevention of fistula formation in TIPU surgery. PATIENTS AND METHODS Study population After approval from the ethics committee (08.06.2021/1915), we retrospectively reviewed the re- cords of 89 patients who had undergone hypospadias repair in the Pediatric Surgery and the Pediatric Urolo- gy Departments of Prof.Dr.Cemil Taşçıoğlu City Hos- pital and Trakya University Hospital between 2015 and 2020 . Patients of only two surgeons were enrolled in the study. Patients who were operated on with TIPU procedure for distal and midpenile hypospadias were included in the study. Study design This study was designed as a retrospective study and conducted with patients of two different centers. Pa- tients’ files, examination notes and surgery notes were investigated and surgical complications, mainly ure- throcutaneous fistula and meatal stenosis were record- ed. Urology Journal/Vol 19 No. 4/ July-August 2022/ pp. 315-319. [DOI:10.22037/uj.v19i.7098] PEDIATRIC UROLOGY Inclusion criteria Patients operated with TIPU procedure for distal and midpenile hypospadias were included in the study. Pa- tients with proximal hypospadias, even if they were operated on with single stage TIPU procedure, and pa- tients with repeated TIPU procedures were not included in the study. Surgical technique The standard technique of TIPU was used for hypospa- dias repair in all patients. Briefly; after placing a traction suture at the tip of the glans, a U-shaped incision extend- ing along the edges of the urethral plate to healthy skin, proximal to the hypospadiac meatus is made. Then, pe- nis was degloved and if there is any chordee, it was cor- rected by dorsal plication. The urethral plate was wid- ened by a deep midline incision including the mucosa and submucosa from the midglandular meatus to the tip of the urethral plate. This incised urethral plate was then tubularized in a one layer running subcuticular fashion with absorbable 6/0 or 7/0 polydioxanone sutures (PDS, Ethicon) over a 6 –or 8- Fr. feeding tube, depending on the age and the width of native urethral plate. In Group 1 (ventral based dartos flap N=45), after completion of urethroplasty, a ventral based vascularized dartos flap was created from both the right and the left side of the urethral corporal groove (Figure 1a,1b). The dissection was terminated before the native meatus was reached to avoid any injury threatening vascular supply of the flap. To cover neourethra completely, the flap was fixed into the lateral recesses of the raised glans’ wings with absorbable sutures. In Group 2 (dorsal preputial dartos flap N=44), the sutures were placed to the borders of the inner face of the prepuce, and the flap was incised just into the subcutaneous tissue level. The underlying dar- tos layer was sharply dissected to the base of the penis. Thus, a vascularized dorsal preputial dartos flap was harvested (Figure 2). The flap was then rotated from the lateral side of the penis to cover the neourethra, and sutured around the neomeatus and inner surface of the glandular wings on each side, using interrupted absorb- able sutures. In both groups; the glandular wings were brought gently together with no tension and closed over the neourethra and dartos flap. In all patients, the ure- Group 1 (N=45) Group 2 (N=44) P value Age (years) Mean ± SD 4.8 ± 2.5 5.4 ± 2.5 .182a Median ( IQR) 4.0 (3.0-6.5) 5.0 (4.0-7.0) Mean difference: 0.6 Follow-up (months) Mean ± SD 25.6 ±11.7 26.5 ± 13.0 .858a Median ( IQR) 24.0 (21.0-36.0) 24.0 (12.0-36.0) Mean difference: 0.9 N (%) N (%) Distal penile 40 (88.9 %) 38 (86.4 %) .714b Mid penile 5 (11.1 %) 6 (13.4 %) Chordee 9 (20 %) 6 (13.4 %) .423b Table 1. Clinical features of the patients aMann - Whitney U Test bChi-Square Test Figure 1. a: Ventral appearance of the ventral based flap. b: Appearance from above the flap Dartos flap to prevent fistula formation in hypospadias – Yiğit et.al Vol 19 No 4 July-August 2022 316 thral catheter was removed 1 week after the operation. Until the time of catheter removal, oral antibiotics and anticholinergics were used to prevent postoperative in- fection and urinary leakage due to bladder irritation. Evaluation Surgical complications were collected retrospectively as the main outcomes of this trial. The total number of surgical complications and specifically the rate of fistu- la formation were compared between the two different flap techniques used. Statistical analysis The data were analyzed using IBM SPSS version 26.0 (IBM Corp. Released 2019. IBM SPSS Statistics for Windows, Version 26.0. Armonk, NY: IBM Corp) sta- tistical software. The continuous variables were pre- sented as mean ± SD and median (minimum-maximum) values; the categorical variables were presented as numbers and percentages. Mann-Whitney U Test was used to compare the mean age of the two groups. Type of hypospadias, chordee and complication percentages of two groups were compared using Chi-square test and Fisher’s exact test respectively. RESULTS 89 patients with distal and midpenile hypospadias who were operated on with TIPU technique were includ- ed in the study. The mean age of the patients was 5.1 years (range 1-12). 78 patients had distal penile and 11 patients had midpenile hypospadias. There was no sig- nificant difference between the groups in terms of age, meatus location, and the presence of chordee (P > .05) Clinical features of the patients are shown in Table 1. Mean follow-up was 25.6 ±11.7 (median:24, IQR:21- 36) months for Group 1 and 26.5±13.0 ( median:24, IQR :12-36) months for Group 2. There was no statis- tical significance between groups in terms of follow-up duration (P = .858) We recorded postoperative complications in 15 pa- tients (33.3 %) in Group 1, and in 4 patients (9.1 %) in Group 2. In Group 1, urethrocutaneous fistula was detected in 10 patients (22.2 %), and meatal stenosis in 5 patients (11.1 %). There was urethracutaneous fistula in all patients who also had meatal stenosis. In Group 2, fistula was detected in 2 patients (4.6 %) and stenosis in 2 patients (4.6 %). All patients with meatal stenosis had also urethrocutaneous fistula. These patients were easily treated with urethral dilatation. The frequency of fistula was found to be statistically higher in Group 1 patients ( 95 % CI : 1.145- 58.83 , OR = 5.892 , P < .05). There was no significant difference between the groups in terms of stenosis frequency (95% CI : 0.2807 - 24.22 , OR = 2.083 , P = .284 ). Complications belonging to the groups are listed in Table 2. In the postoperative Dartos flap to prevent fistula formation in hypospadias – Yiğit et.al Group 1 (N=45) Group 2 (N=44) Total (N = 89) OR (95%CI) P value Fistula 10 (22.2%) 2 (4.6 %) 12 (13.4 %) 5.892 (1.145- 58.83) .029a Stenosis 5 (11.1%) 2 (4.6%) 7 (7.8 %) 2.083 (0.2807, 24.22) .676a Total 15 (33.3%) 4 (9.1) 19 (21.3 %) 4.912 (1.379, 22.43) .005b Table 2. Postoperative complications aFisher’s Exact Test bChi-Square Test Figure 2. Dorsal preputial dartos flap is rotated from the lateral side of the penis. Pediatric Urology 317 period, we did not detect any vascular complications of the flap or penile rotation in any patient. DISCUSSION Although there are many different surgical techniques for hypospadias repair, the ideal surgical procedure with the least complication rate is yet to be described. TIPU operation has gained respect by pediatric urolo- gists for the treatment of many different types of hypo- spadias (3,13,14) . Moreover, TIPU has been used not only for primary hypospadias repair surgery but also used for reoperation of hypospadias(15,16). Despite obvious excellent surgical results with this technique, urethro- cutaneous fistula still remains to be a complication even in well-experienced hands. The rates of fistula for TIPU procedure in distal and proximal types of hypospadias and in the reoperation cases as well were reported in a variable range of 0-to-33 % (4,5,13,15,16). The risk of fistula formation without a flap, covering neourethra, is higher than the techniques where a flap was used. Telfer et al. reported that using a protective intermediate layer reduced the fistula rate from 64 to 4.5 %(17) . One of the most important factors in avoiding the fistula formation is to cover the noeurethra with a sec- ond layer. It has been suggested that the interposition of a well vascularized tissue between neourethra and pe- nile skin reduces the incidence of fistula(3,8,18) . Initially, an epithelialized skin flap technique was described by Smith in 1973 as an intermediate layer(19) . Since then, various procedures and different tissues such as de-epi- thelialized skin, tunica vaginalis, and dartos flaps were described to solve this problem. Baccala et al. have used de-epithelialized dorsal skin flaps as interposed tissue to cover neourethra(12). Shan- berg et al. have reported that a lateral based de-epithe- lialized skin flap was successfully used in reoperated hypospadias patients(20). Although Snodgrass has de- scribed using a dorsal based dartos flap in the original article of himself in 1994, many pediatric urologists have already used ventral based dartos flap and its mod- ifications in TIPU. Furness reported that using the ven- tral based vascularized dartos flap to cover the neoure- thra in TIPU , has a success rate of 98.2 % without any major complications(21). In a recent study by Carmine et al., dissection of fascial flaps also demonstrated a re- duction in stenotic complications even in the surgical correction of phymosis(22). In a prospective randomized comparative study, Sa- vanelli et al. showed that the use of ventral based vas- cularized subcutaneous dartos tissue has reduced fistula formation compared to non- covered urethroplasty in TUPU repair for distal hypospadias(23) . The fistula rate was reported as 3.8% in this study. Soygur et al. have used the ventral based dartos flap in combination with mucosal collars as an effective modification. The au- thors reported that the incidence of the fistula was 8.3 %(11) . In addition, it was revealed in a study that using ventral based dartos flap in several different kinds of urethroplasty reduced the fistula formation(10). On the other hand, Smith used the ventral based pedicle flap for covering the neourethra in TIPU in 64 patients and reported that fistula rate was 12,5 % (24). On the contra- ry, our fistula rate in group 1 was 22.2 %. Probably, the most important reason of a high fistula rate in our study was technical failure in the preparation of the ventral based flap, which resulted in insufficient blood supply of the flap itself or a very thin flap tissue, which com- promised the perfusion. In the original article of Snodgrass, a transverse island of dorsal subcutaneous tissue was used to cover the ne- ourethra(3) . Later on, different reports reported mobi- lizing a vascularized pedicle flap from dorsal prepuce and transposing it to the ventral side of the penis(25,26) . Because the latter technique was reported to cause some potential complications such as penile torsion, chordee or skin loss, Sözübir and Snodgrass performed a pedi- cled dartos flap, which was buttonholed and transposed ventrally for urethral coverage(18). However, we sug- gest that if the dorsal dartos is dissected deeply through the radix of penis without causing any tension of skin, these complications can easily be avoided. Fistula rates in TIPU using dorsal preputial dartos flap have been reported to vary from 0 % to 13 % (8,18). Furthermore, there are studies suggesting that the use of a double dor- sal dartos flap was more effective than a single layer flap(9,27). The fistula rate after using a double flap was reported as 0 % in both studies. Jia et al. compared the complication results of TIPU repair using either dorsal dartos flap or meatus-based ventral dartos flap(28). They reported ventral skin necro- sis in 2.7 % of patients and penile rotation in 3.8% of patients in the dorsal dartos flap group (P = .039, P = .016 respectively) Fistula rates were found to be 2.7% in the dorsal dartos flap group and %2.9 meatus-based ventral dartos flap group (P = .902). In another study, Fahmy et al. compared the results of dartos flap and tunica vaginalis flap and stated that complication rates were the lowest in the patients with double dartos flap (P = .004)(29) . He also stated that there may be com- plications such as vascular and penile rotation with the dartos flap. In our study Group 2 consisted of patients that we used dorsal preputial dartos flap. The flap was harvested from preputial skin and deeply dissected to the radix penis, and then the flap was transposed from the left or right side to the ventral aspect of the penis. Penile rotation was avoided because the flap has dis- sected without tension through the radix penis. Besides, we have not detected any vascular complications in our dorsal flaps. The use of this technique achieved satis- factory outcomes in our patients. In this group, all fistu- las developed only in association with meatal stenosis. We suppose that the meatal stenosis could be the un- derlying reason for urethrocutaneous fistula formation. The strength of this study is that it was conducted with a homogenous patient group with similar age and similar type of hypospadias. The weakness of this study is that it is a retrospective study. Further prospective studies will help to confirm our results. CONCLUSIONS In conclusion, TIPU repair represents an effective pro- cedure to treat patients with hypospadias.. The dorsal preputial dartos flap provided a much better outcomes and less fistula formation in our study. We explain the advantages of this technique is possibly a thicker, wider and more vascularized flap tissue compared to a ventral based flap, which led us to name it as “the blanket of neourethra” or “the omentum of the penis”. We believe that the vascularized dorsal dartos flap procedure is saf- er and more effective than ventral based flap to prevent fistula formation. Dartos flap to prevent fistula formation in hypospadias – Yiğit et.al Vol 19 No 4 July-August 2022 318 CONFLICT OF INTEREST The authors have no conflict of interest to disclose. REFERENCES 1. Baskin LS, Colborn T, Hime K. Hypospadias and endocrine disruption: is there a connection ? Environ Health Perspect. 2001;109:1175- 83 2. Manzoni G, Bracka A, Palminter E, Marrocco G. Hypospadias surgery: When, what and by whom. BJU Int. 2004; 94:1188-95 3. Snodgrass W. Tubularized incised plate urethroplasty for distal hpospadias. J Urol. 1994; 151:464-5 4. Guralnick ML, al-Shammari A, Williot PE, Leonard MP. Outcome of hypospadias repair using the tabularized incised plate urethroplasty. Can J Urol. 2000; 7: 986-91 5. Elicevik M, Tireli G, Sander S. Tubularized incisd plate urethroplasty: 5 years experience Eur Urol. 2004; 46: 655-9 6. Güler Y. TIPU outcomes for hypospadias treatment and predictive factors causing urethrocutaneous fistula and external urethral meatus stenosis in TIPU: Clinical study. Andrologia 2020;52 e13668. doi: 10.1111/ and.13668. Epub 2020 Jun 5 7 . Alshafei A, Cascio S, Boland F, O’Shea N, Hickey A, Quinn F. Comparing the outcomes of tubularized incised plate urethroplasty and dorsal inlay graft urethroplasty in children with hypospadias: a systematic review and meta-analysis. J Pediatr Urol 2020;16:154-61 8. Djordjevic MI, Perovic SV, Slavkovic Z, Djakovic N. Longitudinal dorsal dartos flap for prevention of fistula after a Snodgrass Hypospadias procedure. Eur Urol 2006; 50: 53-7 9. Bakan V, Yildiz A. Dorsal double-layer dartos flap for preventing fistula formation in the Snodgrass technique. Urol Int. 2007; 78: 241- 4 10. Hayashi Y, Kojima Y, Nakane A, Karakoma S, Tozawa K, Kohri K. Ventral based dartos flap for the prevention of the urethrocutaneous fistula urethroplasy. Int J Urol 2007; 14:725-8 11. Soygur T, Arikan N, Zumrutbas AE, Gulpinar O. Snodgrass hypospadias repair with ventral based dartos flap in combination with mucosal collars. Eur Urol 2005; 47: 879-84 12. Baccala AA, Ross J, Detore N, Kay R. Modified tabularized incised plate urethroplasty (Snodgrass) procedure for hypospadias repair Urology 2005; 66:1305-06 13. Snodgrass W, Yucel S. Tubularızed incised plate for midshaft and proximal hypospadias repair. J Urol 2007;177:698-702 14. Mustafa M. The concept of tubularized incised plate hypospadias repair for different types of hypospadias. Int Urol Nephrol 2005; 37:89-91 15. Borer JG, Bauer SB, Peters CA, Diamond DA, Atala A, Cilento BG, et al. Tubularized incised plate urethroplasty: expanded use in primary and repeat surgery for hypospadias. J Urol. 2001; 165: 581-5 16. Nguyen MT, Snodgrass W. Tubularized incised plate hypospadias reoperation. J Urol. 2004; 171: 2404-06 17. Telfer JR, Quaba AA, Kwai Ben I, et al. An investigation into the role of waterproofing in a two-stage hypopsadias repair. Br Plast Surg. 1998; 51:542-6 18. Sozubir S, Snodgrass WT. A new algorithm for primary hypospadias repair based on TIP urethroplasty. J Pediatr Surg 2003; 38:1157- 61 19. Smith D. A de-epithelialized overlap, flap technique in the repair of hypospadias. Br J Plast Surg. 1973; 26:106-8. 20. Shanberg AM, Sanderson K, Duel B. Re- operative hypospadias repair using Snodgrass incised plate urethroplasty. BJU Int. 2000; 87: 544-7 21. Furness PD III. Successful hypospadias repair with a ventral based vascular drtos pedicle for urethral coverage. J Urol. 2003; 169:1825-7 22. Carmine P, Mario F, Antonio G, et.al. Circumferential dissection of deep fascia as ancillary technique in circumcision: is it possible to correct phimosis increasing penis size? BMC Urol. 2021; 21:15 23. Savanelli A, Esposito C, Settimi A. A Prospective randomized comparative study on the use of ventral subcutaneous flap to prevent fistulas in the Snodgrass repair for distal hypospadias. World J Urol. 2007; 25: 641-5 24. Smith DP. A comprehensive analysis of a tabularized incised plate hypospadias repair. Urology 2001; 57:778-82 25. Snodgrass W, Koyle M, Manzoni G, Hurwitz R, Caldomone A, Erlich R. Tubularized incised plate hypospadias repair: Results of a multicenter experience J Urol. 1996; 156: 839- 41 26. Cheng EY, Vemulapalli SN, Kropp BP. et al. Snodgrass hypospadias repair with vascularized dartos flap: the perfect repair for virgin cases of hypospadias. J Urol. 2002; 168:1723-6 27. Kamal BA. Double dartos flap in tabularized incised plate hypospadias repair. Urology 2005; 66:1095-8 28. Jia W, Liu G, Zhang L, et. al. Comparison of tubularized incised plate urethroplasty combined with a meatus-based ventral dartos flap or dorsal dartos flap in hypospadias. Pediatr Surg Int. 2016;32 : 411-5 29. Fahmy O, Khairıl-Asri MG, Schwentner C, et al. Algorithm for Optimal Urethral Coverage in Hypospadias and Fistula Repair: A Systematic Review. Eur Urol. 2016; 70 : 293-8 Dartos flap to prevent fistula formation in hypospadias – Yiğit et.al Pediatric Urology 319