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Midline Perineal Urethrostomy

The midline approach to perineal urethrostomy (PU) is the contemporary default for creating a permanent perineal stoma in complex anterior urethral stricture disease. A single vertical midline perineal incision is used universally; the stoma-creating technique — a loop (urethral plate matured directly to skin) or a 7-flap (a laterally based perineal skin flap advanced into the depth of the wound) — is then chosen intraoperatively based on the urethra-to-skin distance. This algorithmic midline framework, refined by Morey and colleagues from the original French/Hudak/Morey 7-flap, has largely replaced the older commit-from-the-outset inverted-U techniques, delivering ≥ 92% long-term success with markedly lower wound morbidity.[1][2][3]

This page covers the midline approach and its two options. For the inverted-U flap alternative, see Blandy Perineal Urethrostomy. For graft-augmented PU — a dorsal buccal-mucosa onlay added to widen the stoma, performable through either a midline or an inverted-U incision — see Augmented Perineal Urethrostomy. For salvage of a failed PU when local perineal tissue is depleted, see Propeller Flap PU Revision.

Why Midline, and the Two Options​

The midline vertical incision is preferred over the inverted-U on anatomic grounds (fewer neurovascular structures crossed, lower SSI — detailed below). From that common starting incision, two stoma-creating options span the full range of anatomy:

  • Loop technique — when the spatulated urethra reaches the perineal skin without tension (distal strictures, lower BMI), the dorsal urethral plate is preserved and the urethra is matured directly to the skin in a loop configuration, with no skin flap.
  • 7-flap technique — when the healthy proximal urethra sits deep within the perineum (obesity, proximal transection), bringing it to the surface is impossible without tension. The 7-flap inverts the problem: a laterally based skin flap is advanced into the depth of the wound to meet the urethra, rather than mobilizing the urethra to the surface.[1][2]

The 7-flap derives its name from its shape resembling the number "7": a horizontal limb running along the midline incision (advanced deep into the wound to reach the urethra) and a vertical limb extending laterally (the pedicle base, supplied by perineal vasculature).[1]

Indications​

  • Complex, long-segment anterior urethral strictures (median ~ 8 cm, range 2.5–18 cm).[2]
  • Failed prior urethroplasty or revision of a failed prior PU.[2][3]
  • Lichen sclerosus and other adverse-etiology strictures.[3]
  • Older or comorbid patients who are poor candidates for complex multi-stage urethroplasty.[4][5]
  • High BMI — mean BMI 34.9 kg/m² in the 7-flap cohort vs 30.0 in the loop cohort (p = 0.01).[2]

The AUA 2023 urethral stricture guideline amendment endorses PU as a long-term treatment option, either as an alternative to urethroplasty (Conditional Recommendation) or specifically for patients at high risk for reconstruction failure (Expert Opinion).[5]

The Algorithmic Midline Approach​

Both the 7-flap and its companion loop technique start with the same midline perineal incision. The decision between them is made intraoperatively after the urethra is exposed and transected, based on the urethra-to-skin distance.[2] This standardized starting point is a key advantage over Blandy / Johanson, which commit the surgeon to a specific flap design from the outset.

In the McKibben 2019 series of 62 patients:[2]

DecisionCohortMean BMITrigger
Loop technique20 (32.3%)30.0 kg/m²Urethra reaches skin without tension — typically distal strictures or low BMI
7-flap technique42 (67.7%)34.9 kg/m²Long urethra-to-skin distance — obese patients or proximal transection

Step-by-Step Technique​

Positioning and exposure​

  1. Dorsal lithotomy with Allen stirrups; perineum, genitalia, and inner thighs prepped and draped. Suprapubic catheter, if present, left in place.
  2. Vertical midline perineal incision from base of scrotum toward anus, centered over the bulbar urethra.[1][6]

The midline approach is preferred over the inverted-U: cadaveric studies show it damages 1.6–2.0× fewer vessels and nerves with equivalent exposure, and clinical series report significantly lower SSI rates (1.9–3.1% vs 16.4–18.6%, p < 0.05).[6]

Urethral mobilization and transection​

  1. Divide bulbospongiosus in the midline; expose corpus spongiosum and bulbar urethra.
  2. Mobilize the urethra circumferentially.
  3. Identify the strictured segment by palpation, visual inspection, and bougie / catheter passage from the meatus.
  4. Transect the urethra at the level of healthy, well-vascularized proximal urethra — bulbar or membranous, depending on stricture extent.[1]
  5. Discard the distal strictured segment.
  6. Spatulate the proximal stump ventrally to a wide fish-mouth opening (calibrate to ≥ 24–30 Fr).[7]
  7. Confirm healthy mucosa — pink, well-vascularized, pliable.

Intraoperative decision​

  1. Test whether the spatulated stump can be brought to the perineal skin without tension.
    • Yes → Loop technique: preserve the dorsal urethral plate, mobilize to the skin, and suture the spatulated urethra directly to the perineal skin edges in a "loop" configuration (dorsal plate as posterior wall; skin sutured to lateral and ventral urethral margins).
    • No → 7-flap technique: design a laterally based 7-shaped perineal skin flap to bridge the depth.

7-flap design, elevation, and inset​

  1. From the midline incision, design a laterally based 7-shaped flap with horizontal limb along the midline (the portion advanced into the wound) and vertical limb extending laterally (the pedicle base).[1]
  2. Elevate the flap full-thickness with subcutaneous fat and lateral pedicle blood supply intact.
  3. Advance and rotate the flap medially and deep into the perineal wound to reach the transected urethra.
  4. Suture the tip of the flap to the spatulated proximal urethral stump with absorbable suture (typically 4-0 or 5-0 polyglycolic acid).
  5. Suture the lateral edges of the flap to the remaining perineal skin edges to complete the urethrostomy. End-result: a widely patent, well-vascularized stoma at the perineum.

Catheter and closure​

  1. Place a 16–18 Fr Foley through the urethrostomy into the bladder.
  2. Close the perineal wound in layers.
  3. Catheter typically removed at 1–2 weeks postoperatively.

Outcomes​

SeriesnSuccessMedian FUNotable
French 2011 (first description)[1]10 (7-flap)90%—Outpatient setting, no perioperative complications
McKibben 2019 (algorithmic)[2]42 (7-flap) / 20 (loop)92.9% / 100%30.7 moPGI-I 1.0 ("very much improved")
Joshi 2024 (midline PU)[3]10395.1%61 mo86% satisfied / very satisfied; 5.8% complication rate
Fuchs 2018 (PU overall)[4]7794.8%50.7 moPU > BMG (78.5%) and skin flap (78.2%), p = 0.003
Klemm 2024[8]7684% retreatment-free55 moHigh satisfaction; preserved continence

Functional Outcomes and Quality of Life​

  • Voiding — significant Qmax and LUTS improvement.[8][9]
  • Continence — generally preserved; median ICIQ-UI of 0 in the long-term Klemm cohort.[8]
  • Sexual function — stable EF in most series with bimodal distributions; de novo ED ~ 24%.[8][10]
  • Satisfaction — 85–88% satisfied or very satisfied; 76% unbothered by sitting to urinate.[3][9]

Complications, Risk Factors, and Salvage​

Complications are generally mild and self-limited (~ 5.8%).[3] The dominant failure mode is stomal stenosis (5–16% across series).[2][8]

Risk factors​

  • Prior radiation is the single dominant predictor, with OR 11.2 for stenosis on multivariate analysis even when the dorsal plate is preserved.[7] Hughes 2020 characterized the underlying histopathology — post-radiation urethral specimens show increased collagen density (p = 0.01), increased hyalinized fibrosis (p = 0.03), and most critically decreased vascularity (p = 0.0005) — the mechanism that disables the longitudinal blood-supply protection on which dorsal-plate preservation relies.[14]
  • Elevated BMI and older age are independent predictors in the Blandy / inverted-U literature.[11]
  • Suprapubic catheter at the time of surgery marks more severe disease or prior failed interventions and predicts failure in the same series.[11]

Stenosis-salvage ladder​

Stomal stenosis after PU is managed in a stepwise fashion, with most patients salvageable without abandoning the perineal stoma:

  1. Single dilation — converted 4 of 7 Myers / McAninch failures to secondary success, raising overall success from 83% to 93%.[7]
  2. Redo PU using the 7-flap — the 7-flap can revise a failed PU from any prior technique; demonstrated in the original French 2011 series and salvaged 2 of 4 failures in Shinchi 2021.[1][9]
  3. BMG composite stomal repair (Kamat 2008) — a buccal mucosa graft is used to widen the stenotic segment, creating a composite skin-and-mucosa stoma. Particularly useful when lichen sclerosus / BXO threatens the skin component of the stoma.[15]
  4. Posterior thigh propeller flap revision — when local perineal tissue is depleted (radiated, scarred, multiply operated), a perforator-based flap brings healthy tissue from outside the zone of injury. See Propeller Flap PU Revision.[12]
  5. Penile skin graft composite stoma — alternative composite-stoma salvage demonstrated in 1 of 4 failures in Shinchi 2021.[9]

Graft-Augmented PU​

When the dorsal urethral plate is compromised (extensive scarring, prior radiation, or lichen sclerosus) or a wider, more durable, non-hair-bearing meatus is needed, the perineal urethrostomy can be augmented with a dorsal onlay buccal-mucosa graft at the time of creation — a modification (DeLong / Jordan) that addresses the dominant failure mode of stomal stenosis. Because it can be performed through either a midline or an inverted-U incision, it is covered on its own page: see Augmented Perineal Urethrostomy.

Loop vs 7-Flap — At a Glance​

FeatureLoop Technique7-Flap Technique
Proportion of cases (McKibben 2019)32.3%67.7%
Mean BMI30.0 kg/m²34.9 kg/m²
IndicationShort urethra-to-skin distance, distal strictures, low BMILong urethra-to-skin distance, proximal transection, high BMI
Flap designNone — urethral plate mobilized to skinLaterally based 7-shaped perineal skin flap
Blood supplyDorsal urethral plate longitudinal supply preservedLateral perineal pedicle
Success100% (20 / 20)92.9% (39 / 42)
Reoperative useLimitedCan revise failed PU

Comparison With Traditional PU Techniques​

The midline algorithmic approach (loop / 7-flap) outperforms the Blandy inverted-U and Johanson techniques across multiple endpoints:

  • Lower SSI — midline incision damages fewer neurovascular structures (cadaveric 1.6–2.0×); clinical SSI 1.9–3.1% vs 16.4–18.6% for inverted-U (p < 0.05).[6]
  • Higher patency — midline approach 92.9–100% success vs Blandy 51–75% across mixed-era series.[2][11]
  • Algorithmic flexibility — intraoperative decision rather than pre-committed flap design.[2]
  • Dorsal-plate-preservation option (loop) — when feasible, preserving the dorsal urethral plate and its longitudinal blood supply (Myers / McAninch) minimizes stomal-stenosis risk: primary success 83%, secondary 93%; stenosis primarily in irradiated patients (OR 11.2).[7]

PU vs Long-Stricture Anterior Urethroplasty​

TURNS data show that for strictures > 6 cm, PU 2-year failure was 14.5% vs 30.2% for long-stricture anterior urethroplasty (p = 0.09), with comparable urinary-function improvement and stable sexual function.[10] PU use has steadily increased at high-volume centers, rising from 4.3% to 38.7% of complex reconstructive case volume over a decade, while penile-skin-flap use has declined.[3] Contemporary evidence supports PU — and the 7-flap specifically — as a primary reconstructive option rather than a last resort, particularly in older, obese, or multiply-operated patients.[3][5][8]

Technical Pearls​

  • Caliber — urethrostomy calibrated to ≥ 24–30 Fr to minimize stenosis risk.[7]
  • Skin selection — perineal skin overlying the perineal artery is non-hirsute or nearly non-hirsute in many men, reducing risk of intra-stomal hair growth.[13]
  • Outpatient feasibility — the original French 2011 series was performed entirely outpatient without perioperative complications.[1]
  • Revision capability — failed PU (any technique) can be revised with the 7-flap or, in compromised local tissue, with a posterior thigh propeller flap.[12]

Videos​

Perineal Urethrostomy with Z-Plasty Flap
AUA Core Curriculum
Perineal Urethrostomy
Sean Elliott MD

References​

1. French D, Hudak SJ, Morey AF. The "7-flap" perineal urethrostomy. Urology. 2011;77(6):1487-1489. doi:10.1016/j.urology.2010.10.053.

2. McKibben MJ, Rozanski AT, Fuchs JS, Sundaram V, Morey AF. Versatile algorithmic midline approach to perineal urethrostomy for complex urethral strictures. World J Urol. 2019;37(7):1403-1408. doi:10.1007/s00345-018-2522-1.

3. Joshi EG, VanDyke ME, Langford BT, Franzen BP, Morey AF. Algorithmic midline approach to perineal urethrostomy is associated with long-term success and high patient satisfaction. Urology. 2024;190:133-139. doi:10.1016/j.urology.2024.03.016.

4. Fuchs JS, Shakir N, McKibben MJ, et al. Changing trends in reconstruction of complex anterior urethral strictures: from skin flap to perineal urethrostomy. Urology. 2018;122:169-173. doi:10.1016/j.urology.2018.08.009.

5. Wessells H, Morey A, Souter L, Rahimi L, Vanni A. Urethral stricture disease guideline amendment (2023). J Urol. 2023;210(1):64-71. doi:10.1097/JU.0000000000003482.

6. Lin Y, Luo D, Liao B, et al. Perineal midline vertical incision versus inverted-U incision in urethroplasty: which is better? World J Urol. 2018;36(8):1267-1274. doi:10.1007/s00345-018-2267-x.

7. Myers JB, Porten SP, McAninch JW. The outcomes of perineal urethrostomy with preservation of the dorsal urethral plate and urethral blood supply. Urology. 2011;77(5):1223-1227. doi:10.1016/j.urology.2010.10.041.

8. Klemm J, Dahlem R, Schulz RJ, et al. Perineal urethrostomy for complex urethral strictures: long-term patient-reported outcomes from a reconstructive referral center and a scoping literature review. J Urol. 2024;212(5):738-748. doi:10.1097/JU.0000000000004169.

9. Shinchi M, Horiguchi A, Ojima K, et al. Evaluation of the efficacy of perineal urethrostomy for patients with anterior urethral stricture: insights from surgical and patient-reported outcomes. World J Urol. 2021;39(12):4443-4448. doi:10.1007/s00345-021-03795-2.

10. Murphy GP, Fergus KB, Gaither TW, et al. Urinary and sexual function after perineal urethrostomy for urethral stricture disease: an analysis from the TURNS. J Urol. 2019;201(5):956-961. doi:10.1097/JU.0000000000000027.

11. Ponce de León J, Salas D, Calderón J, Montlleó M, Palou J. Analysis of prognostic factors of failure in perineal urethrostomy. World J Urol. 2023;41(4):1109-1115. doi:10.1007/s00345-023-04343-w.

12. Schulster ML, Dy GW, Vranis NM, et al. Propeller flap perineal urethrostomy revision. Urology. 2021;148:302-305. doi:10.1016/j.urology.2020.12.002.

13. Jordan GH. Scrotal and perineal flaps for anterior urethral reconstruction. Urol Clin North Am. 2002;29(2):411-416. doi:10.1016/s0094-0143(02)00030-7.

14. Hughes M, Caza T, Li G, et al. Histologic characterization of the post-radiation urethral stenosis in men treated for prostate cancer. World J Urol. 2020;38(9):2269-2277. doi:10.1007/s00345-019-03031-y.

15. Kamat N. Perineal urethrostomy stenosis repair with buccal mucosa: description of technique and report of four cases. Urology. 2008;72(5):1153-1155. doi:10.1016/j.urology.2008.06.072.