Skip to main content

Double Dartos Flap for UCF Prevention and Repair

The double dartos flap is the recommended first-line waterproofing layer for primary distal hypospadias repair, achieving a UCF rate as low as 0–0.6% — the lowest of any coverage technique for this indication.[1][2] Introduced by Kamal in 2005 and endorsed by the European Urology evidence-based algorithm.[1][2] This page covers both primary hypospadias repair (fistula prevention) and UCF repair (secondary surgery) applications.

For alternative waterproofing techniques see Simple Closure + Skin Advancement Flap; for broader UCF context see the male fistula treatment atlas.

Concept and Rationale​

The dartos fascia is the fibroadipose layer between penile skin and Buck's fascia. A single dartos flap provides one waterproofing layer but causes glanular torsion in up to 100% of cases when a unilateral dorsal flap is used — asymmetric tissue pull rotates the glans.[2]

The double dartos flap solves both problems — it provides two overlapping layers of vascularized tissue over the neourethra while distributing tension symmetrically, eliminating both fistula and torsion.[2][3]

Indications​

Based on Fahmy 2016 Eur Urol SR (n = 4,550) and Pezzoli 2025 SR (40 studies):[1][4]

SettingRoleBest evidence
Primary distal hypospadias (TIP / Snodgrass)First-choice waterproofingUCF 0.6% vs 5.1% single dartos (P = 0.004)[1]
Primary midpenile hypospadiasFirst-choice — double dartos reduces UCF to < 5%[4]Pezzoli 2025 SR
UCF repair (secondary surgery)Reasonable option in select cases81% pooled success (Choudhury 2023) — lower than TVF 94.3% or scrotal dartos 94.6%[5]
Proximal hypospadias, recurrent fistula, repeat caseNot recommendedTVF preferred[1]

Surgical Technique​

Two main variants — Kamal dorsal, Cimador ventral — plus the Mekki dorsal-preputial modification.

Variant 1 — Dorsal Double Dartos (Kamal, 2005)​

The most widely used variant; performed during TIP urethroplasty:[2]

  1. Penile degloving — standard circumscribing incision; elevate dorsal preputial / penile skin off the dartos fascia
  2. Dartos flap harvest — dissect the dorsal preputial dartos as a single broad rectangular flap, preserving the proximal vascular pedicle
  3. Bisection — split vertically in the midline to create two equal pedicled wings, each retaining its own lateral penile vascular supply
  4. Lateral rotation — rotate each wing laterally; one from the right side, one from the left, to reach the ventral surface of the penis
  5. Double-layer coverage — lay the two wings over the neourethra in overlapping fashion:
    • First wing sutured to the urethral-plate / neourethra edges with fine absorbable suture (6-0 or 7-0)
    • Second wing placed over the first with slight offset, secured similarly
  6. Glansplasty + skin closure — approximate glans wings over the double dartos layer; close penile skin

Key principle: symmetric bilateral rotation cancels the rotational vectors that cause torsion with a unilateral flap.[2]

Variant 2 — Ventral Double Dartos (Cimador, 2013)​

Cimador 130-patient RCT:[3]

  1. After penile degloving, mobilize the ventral dartos fascia from the ventral penile skin on either side of the urethral plate
  2. Raise two separate ventral dartos flaps, each based laterally
  3. Rotate medially to cover the neourethra in double-layer overlapping fashion
  4. Avoids dorsal dissection entirely — preserves dorsal penile vasculature

Lowest complication rate of all techniques tested; only 1 UCF in the double ventral dartos group vs higher rates in single ventral and dorsal preputial groups.[3]

Variant 3 — Double Dorsal Preputial Dartos (Mekki 2024)​

n = 105 single-surgeon series (54 double, 51 single):[6]

  1. Harvest dorsal preputial dartos as a broad flap
  2. Divide into two separate flaps
  3. Rotate each to cover the neourethra in two layers
  4. 0% UCF in double-flap group vs 9.8% single (P = 0.024) at 6 mo – 8 yr follow-up

Application in UCF Repair (Secondary Surgery)​

When used for fistula repair rather than primary prevention:

  1. Fistula excision — circumscribing incision, dissect to urethral base, excise tract
  2. Urethral closure — primary closure with fine absorbable suture
  3. Dartos mobilization — penile dartos adjacent to fistula site. If dorsal is non-fibrotic from prior surgery, bisect and rotate as above. Otherwise use ventral dartos from penile shaft
  4. Double-layer coverage — two overlapping dartos layers over the urethral closure
  5. Skin closure — penile skin closed with suture lines offset from the dartos and urethral closures

Pooled UCF-repair success: 81% — significantly lower than TVF (94.3%) or scrotal dartos (94.6%).[5] Reason: penile dartos in the setting of prior surgery is often fibrotic and devascularized, limiting its waterproofing effectiveness.[5][7]

Outcomes​

StudynSettingTechniqueUCF rateTorsionFollow-up
Kamal 200542 double vs 54 singlePrimary distal TIPDorsal double dartos0% vs 3.7%0% vs 100%NS[2]
Cimador 2013 RCT130 totalPrimary distal TIPDouble ventral dartos vs othersLowest (1 UCF)NRNS[3]
Mekki 202454 double vs 51 singlePrimary distalDouble dorsal preputial0% vs 9.8% (P = 0.024)0%6 mo – 8 yr[6]
Fahmy 2016 pooled855Primary distal TIPDouble dartos (all variants)0.6%NRVariable[1]
Choudhury 2023 metaPooledUCF repairDouble dartos81% success (19% recurrence)NRVariable[5]
Pezzoli 2025 SR40 studiesPrimary distal + midpenile TIPDouble dartos0–12% distal, ~ 5% midpenileMinimalVariable[4]

Double Dartos vs Single Dartos vs TVF — Head-to-Head​

FeatureSingle dartosDouble dartosTunica vaginalis
UCF rate (primary distal)5.1%0.6% (P = 0.004 vs single)2.0%[1]
UCF rate (primary proximal)8.8%Limited dataLower[1]
UCF rate (fistula repair)78.8% success81% success94.3% success[5]
UCF rate (repeat / recurrent)18.6%Limited data6.4% (P = 0.020)[1]
Glanular torsion90–100% mild-moderate0%2.4% penile torque[2][3]
Operative timeShortestSlightly longer~45 min longer[14]
Tissue sourcePenile (same field)Penile (same field)Scrotal (different field)
Best indicationSimple primary casesPrimary distal hypospadiasRecurrent / proximal / fistula repair

Advantages​

  • Eliminates glanular torsion — symmetric bilateral rotation neutralizes the rotational forces; 0% torsion vs 90–100% with single dartos[2][6]
  • Lowest UCF rate for primary distal hypospadias — 0.6% across 855 patients, vs single dartos 5.1% (P = 0.004) and TVF 2.0%[1]
  • No additional incision required — harvested from the same operative field during standard penile degloving[2]
  • No testicular complications — no risk of ascent, torsion, or atrophy (theoretical TVF concerns)[2][6]
  • Technically straightforward — bisection of dorsal dartos adds minimal complexity to standard TIP[2]
  • Shorter OR time vs TVF (no scrotal incision, testicular delivery, or subcutaneous tunneling)[14]

Limitations​

  • Inferior for UCF repair — 81% pooled success vs TVF 94.3% / scrotal dartos 94.6% (penile dartos often scarred from prior surgery)[5]
  • Not recommended for recurrent fistulas — TVF superior (6.4% vs 18.6% recurrence, P = 0.020)[1]
  • Not recommended for proximal hypospadias — single dartos 8.8% UCF; double data limited; TVF preferred[1]
  • Requires intact prepuce / dorsal dartos — in circumcised patients or those with prior dorsal dissection, dorsal dartos may be unavailable or insufficient. The ventral dartos variant (Cimador) is the alternative[3]
  • Limited tissue bulk — dartos is thinner than tunica vaginalis, particularly in infants, providing less robust waterproofing in complex cases
  • Midpenile data weaker than distal — single dorsal dartos performs poorly in midpenile (12.5–36.4% UCF); double dartos reduces this to < 5%[4]

Dartos Coverage as an Independent Risk-Reduction Factor​

Braga 2010 (n = 153 consecutive TIP repairs) — absence of dartos flap coverage is an independent, clinically modifiable risk factor for UCF. In nonstented repairs: fistula rate 37% without dartos vs 9% with dartos (P = 0.002; OR 0.16). Stenting acts as an effect modifier — the protective effect of dartos coverage is most pronounced in nonstented repairs.[15]

Scrotal Dartos Flap — Related but Distinct​

The scrotal dartos flap is harvested from the scrotal wall (not penile shaft) — separate technique from the penile double dartos flap. Provides tissue from outside the scarred penile field, similar to TVF. 94.6% success in UCF repair (comparable to TVF).[5]

  • Muruganandham series — scrotal dartos wrapping of 2–4 mm fistulas: 90.5% success (2 recurrences in 21); no scrotal or testicular complications[16]
  • Churchill technique — fibroadipose tissue between scrotal skin and tunica vaginalis, vascular pedicle based at the penoscrotal angle, reaches distal penile shaft without tension; 100% excellent cosmesis and no fistula in repeat hypospadias series[17]

Evidence-Based Algorithm — Where Double Dartos Fits​

Based on Fahmy 2016 Eur Urol SR:[1]

  1. Primary distal hypospadias → Double dartos (0.6% UCF)
  2. Primary midpenile hypospadias → Double dartos or TVF (both < 5%)
  3. Primary proximal hypospadias → TVF
  4. First-time UCF repair → TVF (94.3%) > scrotal dartos (94.6%) > double dartos (81%)
  5. Recurrent UCF repair → TVF (6.4% vs 18.6% for dartos)

Technical Pearls​

  • Preserve the vascular pedicle — when bisecting dorsal dartos, ensure each wing retains adequate blood supply from lateral penile vessels; avoid excessive cautery[2]
  • Adequate flap width — each wing should extend beyond the neourethral suture line by ≥ 3–5 mm on each side
  • Overlapping, not stacking — the two wings should overlap in the midline ventrally, not simply be stacked; this creates a broader area of double-layer coverage[2]
  • Offset suture lines — dartos fixation sutures should not overlie the neourethral suture line
  • Avoid tension — if wings retract after rotation, the neourethra is uncovered; mobilize generously
  • Consider ventral dartos in circumcised patients or limited dorsal dartos availability[3]
  • Two-layer neourethral closure (running subcuticular + interrupted subepithelial) combined with double dartos coverage achieves near-zero complications — Cheng multi-institutional series of 514 TIP repairs with vascularized dartos + 2-layer closure: 0% fistula in 414 distal cases[18]

Key Takeaways​

  • First-line waterproofing for primary distal hypospadias — 0.6% UCF across 855 patients (Fahmy SR); 0% torsion (vs 90–100% with single dartos).
  • Symmetric bilateral rotation is the defining principle — neutralizes the rotational vectors causing torsion.
  • Three technique variants: dorsal preputial (Kamal), ventral (Cimador), dorsal preputial bisected (Mekki) — all converge on the principle of two overlapping vascularized layers.
  • Inferior to TVF / scrotal dartos for UCF repair (81% vs 94–95%) because penile dartos is often scarred from prior surgery; not recommended for recurrent or proximal cases.
  • Combined with two-layer neourethral closure in the Cheng 514-TIP series: 0% fistula in 414 distal cases.

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. Shankar KR, Losty PD, Hopper M, Wong L, Rickwood AM. "Outcome of hypospadias fistula repair." BJU Int. 2002;89(1):103–105.

14. 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

15. Braga LH, Lorenzo AJ, Suoub M, Bägli DJ. "Is statistical significance sufficient? Importance of interaction and confounding in hypospadias analysis." J Urol. 2010;184(6):2510–2515. doi:10.1016/j.juro.2010.08.035

16. Muruganandham K, Ansari MS, Dubey D, et al. "Urethrocutaneous fistula after hypospadias repair: outcome of three types of closure techniques." Pediatr Surg Int. 2010;26(3):305–308. doi:10.1007/s00383-009-2490-z

17. Churchill BM, van Savage JG, Khoury AE, McLorie GA. "The dartos flap as an adjunct in preventing urethrocutaneous fistulas in repeat hypospadias surgery." J Urol. 1996;156(6):2047–2049.

18. 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