Double Dartos Flap for Urethral Coverage and UCF Repair
A double dartos flap provides two vascularized tissue layers over a urethral suture line. Most comparative evidence concerns prevention of urethrocutaneous fistula (UCF) during primary pediatric hypospadias repair, especially distal tubularized incised plate urethroplasty (TIP). Those low fistula rates should not be presented as the success rate of repairing an established, recurrent or adult fistula.[1][4][5]
For established fistulas, compare Simple Closure and Skin Advancement, Tunica Vaginalis Flap, Scrotal Flaps and PATIO Repair. See the urethral reconstruction atlas when a fistula accompanies stricture, breakdown or a larger urethral defect.
Selection
Dartos coverage is useful when enough healthy local tissue can be mobilized without compromising penile skin perfusion, constricting the neourethra or placing the glans closure under tension. Prior circumcision, scarring, previous flap harvest and ventral skin deficiency affect the available options; the number of layers alone does not determine the quality of a repair.[4][9]
The current EAU pediatric hypospadias chapter states that tunica vaginalis may yield better results than dartos, and recommends a double layer when dartos is used. This is guidance about urethroplasty coverage, not a declaration that double dartos is the best repair for every UCF. Redo hypospadias reconstruction remains individualized.[9]
Before closing an established fistula, evaluate the distal urethra and meatus, tissue quality, associated dehiscence and the need for additional urethral reconstruction. Healthy local dartos may be suitable; extensive scarring or deficient tissue may favor another vascularized layer. A recurrent or proximal fistula is not an automatic contraindication to dartos, but primary distal TIP results are an unreliable estimate of its outcome in that setting.[1][5]
Operative principles
Dorsal preputial and ventral dartos techniques differ. A common dorsal approach harvests a vascularized flap during penile degloving, divides it into two adequately perfused portions and brings them over the urethral closure from opposite sides. Ventral dartos can also be configured as double coverage when tissue permits.[2][3][6]
- Preserve blood supply. Separate dartos from the skin carefully, maintaining viable pedicles and adequate skin vascularity. Do not create two layers by excessively thinning or devascularizing an inadequate flap.
- Complete the urethral repair. Confirm that the reconstructed lumen and underlying closure are satisfactory before coverage. Interposition does not compensate for obstruction or a poorly constructed urethroplasty.
- Transfer without twist or traction. Position each component to cover the relevant urethral suture line. Avoid tethering that rotates the penis or compromises the pedicle.
- Secure separate coverage. Fix the layers gently with fine absorbable sutures as appropriate, without narrowing the urethra or creating excessive bulk beneath the glans.
- Reassess the entire closure. Confirm penile alignment, skin and flap perfusion, and tension-free glans and skin approximation. If the available dartos cannot meet these goals, reconsider the coverage choice.[2][4][6]
This is a principles outline, not a substitute for the selected urethroplasty or fistula-closure technique. “Double dartos coverage” and a “two-layer urethral closure” describe different structures.
Evidence for preventing a first postoperative fistula
| Source | Finding | Important limitation |
|---|---|---|
| Fahmy 2016 systematic review | Distal-hypospadias series reported fistula in 5/855 with double dartos and 156/3,077 with single dartos. | These are pooled groups from heterogeneous studies, not one randomized comparison. Selection, technique and follow-up differ.[1] |
| Kamal 2005 | Ninety-six TIP repairs: two fistulas among 54 single-flap repairs and none among 42 double-flap repairs. | The unusually frequent torsion in this particular single-flap group is not the incidence of torsion after every single-dartos technique.[2] |
| Cimador 2013 | One hundred thirty children were randomized to dorsal or ventral coverage strategies, with several variants used within these groups; only one fistula was reported after double ventral coverage. | The abstract does not provide that subgroup's denominator or establish a separately randomized comparison of every flap variant.[3] |
| Mekki 2024 | A chronological single-surgeon series compared 51 earlier single-dartos with 54 later double-dartos repairs; no fistula was reported in the double-dartos group. | Nonrandomized, with experience and time-period confounding. The article gives inconsistent single-group fistula counts, so a precise comparative effect is not reproduced here. Neither group had penile torsion.[6] |
| Pezzoli 2025 systematic review | Forty studies of primary distal or midpenile TIP generally supported vascularized coverage, with favorable results in many double-dartos groups. | Redo repairs and established UCF repair were excluded; heterogeneity prevented a reliable comprehensive meta-analysis. Meatal stenosis, skin viability and glans closure remain relevant.[4] |
The historical Cheng series of 514 primary repairs combined a two-layer urethral closure with vascularized dartos coverage. Its favorable results cannot isolate the benefit of double dartos, and the phrase “two layers” should not be reassigned to the flap.[8]
Tunica vaginalis comparison
A 2025 randomized study allocated 88 children to dartos or tunica vaginalis coverage; 84 were analyzed after four losses. Fistulas occurred in 9/43 dartos versus 2/41 tunica vaginalis repairs at the reported assessments. Tunica vaginalis took longer and three patients developed testicular ascent. Dartos could be dorsal or ventral according to the surgeon; this was not a specifically double-dartos-versus-tunica trial. Its small sample and limited follow-up prevent a universal ranking of coverage options.[7]
Evidence for closing an established fistula
The 2023 review of UCF repairs included 2,886 patients from 71 studies. It reported 81% success for double dartos, with different crude proportions for other techniques. These estimates concern fistula repair, unlike the much lower fistula incidence after selected primary distal TIP repairs. Differences between the pooled techniques cannot establish causal superiority because patient selection and reconstructive complexity vary.[5]
Similarly, the 2016 review's comparison of dartos with tunica vaginalis for fistula closure did not demonstrate a statistically significant difference: failures were 11/90 and 5/97, respectively (P = .39). This does not prove equivalence. A healthy, appropriately selected flap and correction of associated urethral problems matter more than applying a pooled percentage to an individual patient.[1]
Follow-up and counseling
Counsel about recurrent fistula, meatal or urethral narrowing, skin or glans breakdown, torsion and the possibility of further reconstruction. Double coverage does not eliminate these complications. Drainage, dressings and activity restrictions follow the underlying repair and local protocol; there is no universal catheter duration established by the double-dartos evidence.[4][9]
Assess healing and the urinary stream, with uroflowmetry and further investigation when age, symptoms or the reconstruction warrant them. Late obstruction and other complications can arise after hypospadias surgery, so early fistula closure alone is an incomplete outcome.[9]
References
1. Fahmy O, Khairul-Asri MG, Schwentner C, et al. "Algorithm for optimal urethral coverage in hypospadias and fistula repair: a systematic review." Eur Urol. 2016;70(2):293–298. doi:10.1016/j.eururo.2015.12.047
2. Kamal BA. "Double dartos flaps in tubularized incised plate hypospadias repair." Urology. 2005;66(5):1095–1098. doi:10.1016/j.urology.2005.05.020
3. Cimador M, Pensabene M, Sergio M, Catalano P, de Grazia E. "Coverage of urethroplasty in pediatric hypospadias: randomized comparison between different flaps." Int J Urol. 2013;20(10):1000–1005. doi:10.1111/iju.12092
4. Pezzoli M, Lo Re M, Carletti V, Masieri L, Mantovani A. "Impact of second-layer coverages on complication rates in primary tubularized incised plate urethroplasty (TIPU) for distal and midpenile hypospadias repair: a systematic review." Pediatr Surg Int. 2025;41(1):240. doi:10.1007/s00383-025-06134-3
5. Choudhury P, Saroya KK, Jain V, et al. "'Waterproofing layers' for urethrocutaneous fistula repair after hypospadias surgery: evidence synthesis with systematic review and meta-analysis." Pediatr Surg Int. 2023;39(1):165. doi:10.1007/s00383-023-05405-1
6. Mekki M, Fredj MB, Messaoud M, et al. "The effectiveness of double dorsal dartos flap for urethroplasty coverage in distal hypospadias repair: a single surgeon approach to preventing urethrocutaneous fistula." Int J Urol. 2024;31(12):1380–1384. doi:10.1111/iju.15572
7. Ramez M, Hashem A, Bazeed M, Dawaba MS, Helmy TE. "Tunica vaginalis or dartos as second layer coverage for distal and mid-shaft penile hypospadias, quo vadis?" World J Urol. 2025;43(1):78. doi:10.1007/s00345-024-05419-x
8. 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(4 Pt 2):1723–1726. doi:10.1097/01.ju.0000026940.33540.31
9. European Association of Urology. EAU Guidelines on Paediatric Urology: Hypospadias. 2026. Guideline.