Modified Bilateral "Butterfly" Scrotal Flap (Yao Technique)
The Yao butterfly flap is a single-stage bilateral axial-pattern scrotal flap in which two symmetric flaps — one from each side of the midline scrotal raphe — are independently pedicled on their respective anterior scrotal arteries and rotated medially to wrap around the denuded penile shaft, resembling butterfly wings. In the original 7-patient series, all achieved satisfactory outcomes with significant penile length gain in both flaccid and erect states; 2 / 7 had small flap-necrosis areas managed conservatively.[1]
For the related single-flap, central-window variant, see Bipedicled Anterior Scrotal Flap (Fakin). For the tunnel variant, see Modified Bipedicle Scrotal Tunnel Flap (Murányi). For the graft alternative, see Penile Skin Grafting. For the full decision framework, see Penile Reconstruction.
Rationale
The Yao butterfly modification was designed to address limitations of prior approaches:[1]
| Prior approach | Limitation |
|---|---|
| Skin grafts (STSG / FTSG) | Scarring / contracture; depend on a well-vascularized recipient bed — fail when residual foreign material on corpora prevents take[1][2] |
| Pribaz staged scrotal flap | Two-stage; prolonged recovery[3] |
| Fakin bipedicled flap | Single midline flap with central window — both pedicles must function simultaneously[4] |
| Jeong (1996) bilateral flaps | T-style ventral coronal anastomosis prone to necrosis[2] |
Key innovation: two independent flaps, each with its own anterior-scrotal-artery pedicle, that meet at the ventral midline end-to-end (no T-junction).[1]
Vascular Anatomy
The butterfly design exploits the three Carrera scrotal territories:[5]
- Two lateral territories — each supplied by an inferior external pudendal artery entering at the midpoint of the scrotal root, fanning over the corresponding hemiscrotum
- One central territory — supplied by branches of the perineal arteries (internal pudendal system) via the posterior scrotum
- Wide inter-anastomoses between the three territories make scrotal skin one of the most reliably perfused tissues in the perineum
Each butterfly wing is centered over an anterior scrotal artery (terminal branch of the external pudendal). Dividing the scrotum along the midline raphe leaves both lateral territories independently perfused — dual independent blood supplies are the defining advantage over single-flap variants.[1][5]
Indications
- Penile skin shortages following trauma (avulsion, bite injuries)
- Scar contracture with pain or erectile dysfunction after prior penile surgery
- Circumferential or near-circumferential shaft defects after tumor excision
- Foreskin / penile-shaft deficiency
- Foreign body granuloma (paraffinoma, siliconoma) — flap survives even with residual material on corpora[1][2]
Prerequisite: intact uninvolved scrotal skin with adequate laxity on both sides of the midline raphe.
Operative Technique
1. Penile degloving and defect creation
- Penis on stretch
- Circumferential incision at the coronal sulcus and a second at the penoscrotal junction (or at the proximal margin of diseased tissue)
- Excise all involved skin / scar / granuloma to Buck's fascia; fully denude the shaft
- Measure circumference and length of the resulting defect
2. Flap design — the "butterfly wings"
- Two symmetric flaps on the anterior scrotum, one on each side of the midline raphe
- Each flap is a rectangular or trapezoidal island with its long axis along the raphe
- Width of each flap ≈ half the shaft circumference (so the two flaps meet at dorsal and ventral midlines)
- Length matches the defect length (coronal sulcus → penile base)
- Pedicle at the lateral scrotal root (anterior scrotal artery entry); free edge along the midline raphe
3. Flap elevation
- Elevate from medial → lateral, beginning at the midline raphe
- Plane above the external spermatic fascia, preserving dartos within the flap (maintains the subdermal plexus)
- Carefully preserve the anterior-scrotal-artery pedicle at the lateral root
- Tunica vaginalis kept intact; testes transiently exposed but covered
4. Flap rotation and wrapping
- Position the denuded shaft between the two elevated wings
- Each flap rotated medially and superiorly from its lateral pedicle
- Right flap covers right hemi-circumference; left flap covers left hemi-circumference
- Flaps meet at dorsal midline and ventral midline of the shaft
5. Inset and suturing
- Distal (coronal) circumferential suture line — distal flap edges to the subcoronal margin
- Proximal (base) circumferential suture line — proximal flap edges to penile base / pubic skin
- Dorsal midline longitudinal suture line — free edges of the two flaps together
- Ventral midline longitudinal suture line — free edges together (end-to-end, not T-junction)
- All with interrupted absorbable sutures
6. Scrotal donor-site closure
- Advance remaining posterior and lateral scrotal skin medially; close primarily
- Drain may be placed if dead-space concern
- Testes re-covered by the remaining scrotal envelope
7. Dressing and postoperative care
- Light compressive dressing
- Foley catheter for early postoperative urinary drainage
- Avoid sexual activity and strenuous activity 4–6 weeks
How It Differs From Other Scrotal-Flap Techniques
| Feature | Yao butterfly | Fakin bipedicled[4] | Murányi tunnel[6] | Jeong bilateral[2] | Shin inverted-V[7] | Pribaz staged[3] |
|---|---|---|---|---|---|---|
| Number of flaps | 2 (independent bilateral) | 1 midline | 1 tunnel | 2 bilateral | 2 bilateral | 1 midline |
| Pedicle | Bilateral, independent | Bilateral, shared | Bilateral via tunnel | Bilateral | Bilateral | Neovascularization |
| Staging | Single | Single | Single | Single | Single | Two-stage |
| Shaft suture lines | Dorsal + ventral longitudinal | Circumferential at base + coronal | Dorsal longitudinal + ventral inverted-V | Dorsal + ventral T-style | Dorsal + ventral inverted-V | Circumferential |
| Ventral junction | End-to-end midline | Circumferential | Inverted-V → longitudinal | T-style (necrosis-prone) | Inverted-V end-to-end | N/A (staged) |
| Window / tunnel | None | Window | Tunnel | None | None | None |
| Series size | 7 | 43 | 49 | 17 | 34 (14 inverted-V) | 8 |
Outcomes — Yao Series (n = 7)[1]
- Etiologies: penile trauma and post-tumor surgery
- Satisfactory outcomes in all 7
- Partial flap necrosis 2 / 7 (28.6%) — small areas only, resolved with conservative wound care; no reoperation
- Complete flap loss 0
- Penile length significantly increased (flaccid + erect, p < 0.05) — the only scrotal-flap series to formally demonstrate this
- Preserved erectile function
- All patients "satisfactory"
Comparative Context
| Outcome | Yao (n = 7) | Fakin (n = 43) | Murányi (n = 49) | Mendel (n = 22) | Jeong (n = 17) | Pribaz (n = 8) |
|---|---|---|---|---|---|---|
| Flap survival | 100% (2 minor necrosis) | 100% (9% partial) | 90% success | 100% (no total loss) | 100% (34 / 34 flaps) | 100% |
| Partial necrosis | 28.6% (minor) | 9% | included in CD 3a | 0% | 0% | 0% |
| Wound dehiscence | 0% | 19% | included in CD 3a | 31.8% | n/r | 25% (minor) |
| Penile length increase | Significant (p < 0.05) | n/r | n/r | n/r | n/r | n/r |
| Erectile function preserved | Yes | 100% erection ability | ED 6.7% | n/r | Yes | Yes |
| Patient satisfaction | All satisfactory | 4.37 / 5 | 90% success | 8 / 10 global | All successful | All satisfactory |
Advantages
- Single-stage — avoids second operation and temporary penile burial
- Dual independent blood supply — if one wing has marginal perfusion, the contralateral remains independently viable; theoretical advantage over the shared-pedicle Fakin design
- No tunnel or central window — direct flap rotation; potentially less risk of pedicle compression / kinking than Fakin or Murányi
- No T-junction — ventral end-to-end closure avoids the necrosis-prone T-style anastomosis of the original Jeong technique
- Flexible asymmetric design — wings can be sized independently if one hemiscrotum has less skin or the defect is eccentric
- Documented penile-length gain — uniquely demonstrated in this series
- Comparable skin quality — thin, elastic, predominantly non-hair-bearing scrotal skin
- No distant donor site — same operative field
- Conceptually straightforward — no microsurgical expertise required
Limitations and Disadvantages
- Smallest published series (n = 7) — complication profile and long-term outcomes less well characterized than Fakin (43) or Murányi (49)
- Higher partial-necrosis rate — 28.6% vs Fakin 9% and Mendel 0% (small numbers, all minor)
- Two longitudinal shaft scars (dorsal + ventral) vs single dorsal scar of Fakin / Murányi — potential cosmesis tradeoff
- Hair-bearing variability — anterior scrotal skin is usually non-hair-bearing but varies by ethnicity / individual
- Bilateral scrotal-flap morbidity — testicular ascension (Mendel ~ 22.7%), scrotal volume reduction, late skin retraction (~ 27.3%) are known class effects[8]
- Single-etiology evidence (trauma / tumor / scar) — paraffinoma applicability is extrapolated
- No long-term follow-up data in the original publication
Comparison With the Original Jeong (1996) Bilateral Flap
The Yao butterfly is a direct modification of Jeong's bilateral scrotal flap:[1][2]
| Feature | Jeong (1996) | Yao butterfly (2022) |
|---|---|---|
| Ventral anastomosis | T-style coronal-scrotal junction | End-to-end midline |
| Ventral necrosis risk | Higher (T-junction) | Lower (no T) |
| Indication | Paraffinoma only | Trauma, tumor, scar contracture |
| Penile length assessment | Not reported | Significant increase (p < 0.05) |
| Format | Text description | Video article (JoVE) |
| Series size | 17 | 7 |
The Shin inverted-V modification (2013, n = 14) addressed the same T-junction necrosis problem via an inverted-V incision at the ventral anastomosis.[7] The Yao butterfly achieves the same anti-necrosis effect by design — the bilateral flaps naturally meet end-to-end at the ventral midline.
Adjunctive Refinements
Kim Y-V dorsal-base advancement (length preservation)
Y-V advancement at the dorsal penile base + partial suspensory-ligament resection added to a bipedicled scrotal flap. n = 5 — prevented penile shortening with universal satisfaction. Could be combined with the Yao butterfly for additional length gain.[9]
Zhao suspensory-ligament division
Combining scrotal flap with suspensory-ligament division — n = 18, significant length gain (flaccid + erect), 83% satisfactory intercourse at 2.3 y. The Yao technique's documented length gain may reflect a similar adjunct.[10]
Patient Selection
| Choose Yao butterfly | Consider alternative |
|---|---|
| Circumferential shaft defect (trauma / tumor / scar) | Skin graft / regional flap if scrotal skin insufficient or involved |
| Adequate bilateral scrotal skin | Two-stage Pribaz if contaminated bed |
| Single-stage preferred with maximal length preservation | Murányi tunnel for larger evidence base and simpler dissection |
| Concern about T-junction necrosis (avoided by design) | Fakin if a single dorsal scar is cosmetically preferable |
| Surgeon preference for two independent flaps |
Key Takeaways
- Two independent bilateral flaps each on its own anterior scrotal artery — distinguishes Yao from single-flap variants
- End-to-end midline ventral closure structurally eliminates the historical T-junction necrosis risk
- Only scrotal-flap series to document significant penile-length gain — though n = 7
- 28.6% minor flap necrosis — counsel patients; managed conservatively in all cases
- Tradeoff: two longitudinal shaft scars vs one in Fakin / Murányi
Cross-references
- Bipedicled Anterior Scrotal Flap (Fakin)
- Modified Bipedicle Scrotal Tunnel Flap (Murányi)
- Penile Skin Grafting
- Penile Primary Closure ± Z-plasty
- Penile Reconstruction
- Scrotal Reconstruction
- Foundations — Plastic Surgery Principles
References
1. Yao H, Zheng D, Xie M, et al. "A Modified Bilateral Scrotal Flap for Penile Skin Defect Repair." J Vis Exp. 2022;(189). doi:10.3791/64017
2. Jeong JH, Shin HJ, Woo SH, Seul JH. "A New Repair Technique for Penile Paraffinoma: Bilateral Scrotal Flaps." Ann Plast Surg. 1996;37(4):386–93. doi:10.1097/00000637-199610000-00007
3. McLaughlin MM, Abbassi B, Pribaz JJ. "Bipedicled Scrotal Flap for Penile Resurfacing." Plast Reconstr Surg. 2024;153(4):935–942. doi:10.1097/PRS.0000000000010811
4. Fakin R, Zimmermann S, Jindarak S, et al. "Reconstruction of Penile Shaft Defects Following Silicone Injection by Bipedicled Anterior Scrotal Flap." J Urol. 2017;197(4):1166–1170. doi:10.1016/j.juro.2016.11.093
5. Carrera A, Gil-Vernet A, Forcada P, et al. "Arteries of the Scrotum: A Microvascular Study and Its Application to Urethral Reconstruction With Scrotal Flaps." BJU Int. 2009;103(6):820–4. doi:10.1111/j.1464-410X.2008.08167.x
6. Murányi M, Varga D, Kiss Z, Flaskó T. "A New Modified Bipedicle Scrotal Skin Flap Technique for Penile Paraffin-Induced Sclerosing Lipogranuloma." J Urol. 2022;208(1):171–178. doi:10.1097/JU.0000000000002480
7. Shin YS, Zhao C, Park JK. "New Reconstructive Surgery for Penile Paraffinoma to Prevent Necrosis of Ventral Penile Skin." Urology. 2013;81(2):437–41. doi:10.1016/j.urology.2012.10.017
8. Mendel L, Neuville P, Allepot K, et al. "Bilateral Pedicled Scrotal Flaps as an Alternative to Skin Graft in Penile Shaft Defects Repair." Urology. 2023;176:206–212. doi:10.1016/j.urology.2023.03.025
9. Kim SW, Yoon BI, Ha US, et al. "Treatment of Paraffin-Induced Lipogranuloma of the Penis by Bipedicled Scrotal Flap With Y-V Incision." Ann Plast Surg. 2014;73(6):692–5. doi:10.1097/SAP.0b013e31828637d3
10. Zhao YQ, Zhang J, Yu MS, Long DC. "Functional Restoration of Penis With Partial Defect by Scrotal Skin Flap." J Urol. 2009;182(5):2358–61. doi:10.1016/j.juro.2009.07.048