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Omental Flap

The greater omentum is the reconstructive urologist's first-choice vascularized pedicled flap for fistula interposition, ureteral wrapping, and pelvic dead-space obliteration when it is accessible, healthy, and long enough to reach. It offers three properties no other flap combines: rich vascular and lymphatic tissue that promotes neovascularization in compromised beds, a porous structure that drains dead-space fluid rather than trapping it, and minimal donor-site morbidity — the omentum is an expendable organ. When VRAM, gracilis, or rectus-based options each bring their own donor cost, the omentum arrives through the same incision as the index operation with essentially no downside — which is why, when available, it is preferred over the rectus flap.

See the overview article: Flaps in GU Reconstruction. Related pages: Peritoneal Flap, VRAM, Gracilis Flap.

Unique Biologic Properties​

The omentum's reconstructive value rests on a small set of properties no other flap combines:[1][2]

  • Angiogenesis — highly vascularized; promotes neovascularization in surrounding tissues, supporting healing in ischemic or irradiated fields
  • Immunologic activity — rich in lymphoid aggregates ("milky spots") and the only body tissue specifically developed for infection resolution
  • Thromboplastin content — facilitates hemostasis in difficult-to-control operative fields
  • Malleability — conforms to irregular defects and regains suppleness after healing, unlike fibrotic periureteral or perivesical tissue
  • Trophic effect — promotes regeneration in surrounding structures, making it a useful matrix for grafting

These properties are why the omentum is preferred whenever it is available, healthy, and long enough to reach.

Anatomy and Vascular Supply​

The greater omentum hangs from the greater curvature of the stomach, draping over the transverse colon and small bowel. In adults it measures roughly 30–40 cm in length and 20–30 cm in width — highly variable with body habitus.

Dual Pedicle System​

The omentum is supplied by the gastroepiploic arcade, a continuous vessel along the greater curvature of the stomach formed by:

VesselOrigin
Right gastroepiploic arteryGastroduodenal artery (branch of common hepatic)
Left gastroepiploic arterySplenic artery

The two vessels anastomose along the greater curvature, forming a closed arcade that gives off branches into the omental apron. This arcade is the pedicle on which the flap is raised.

A cadaveric study of 45 specimens identified three arterial-supply variants:[3]

  • 56% — one right omental, one (or two) middle, and one left omental artery
  • 26% — middle omental artery absent
  • 18% — gastroepiploic artery continues as a left omental artery with smaller connections

Collateral circulation is also maintained via the gastroepiploic arch and Barkow's marginal artery.[4]

Pedicle Selection for Pelvic Reach​

For pelvic reconstruction, one of the two gastroepiploic arteries is sacrificed — this releases the omentum on a single pedicle long enough to rotate down to the pelvis or perineum. In clinical practice, either side provides adequate reach and perfusion; the choice is typically dictated by which direction the omentum drapes naturally and by any prior abdominal dissection that has already compromised one side.

Some surgeons preferentially base on the right (longer, better for pelvic reach by some descriptions). Others describe that either gastroepiploic pedicle delivers sufficient length to reach the pelvis when the flap is raised properly. In practice, both work.

Bilateral Pedicle (for Dual Flaps)​

For bilateral ureterolysis in retroperitoneal fibrosis, the omentum can be divided vertically in the midline, creating two omental flaps — one pedicled on the right gastroepiploic and one on the left — each delivered to the respective retroperitoneal ureter.

Tissue Characteristics​

  • Abundant lymphatic and vascular tissue — promotes neovascularization in compromised beds (radiation, scar, prior fistula)
  • Porous structure — fluid (hematoma, seroma, urine) drains through the omentum rather than accumulating; this is why omentum is the preferred backing for BMG ureteroplasty (fluid drainage prevents the dead space that kills graft take)
  • Expendable — no significant physiologic consequence of omentectomy
  • Immune surveillance function — the omentum concentrates macrophages and lymphoid aggregates ("milky spots") that help sterilize contaminated fields

Harvest Technique​

Open Harvest​

With the abdomen open and the index urologic operation either complete or in progress:

  1. Identify the omentum hanging from the transverse colon and greater curvature.
  2. Decide the base — right or left gastroepiploic, dictated by pedicle length, prior abdominal dissection, and the side of the defect.
  3. Two release options:
    • Fast / standard — divide the omentum at its reflection on the transverse colon. Faster, preserves the full arcade, produces adequate length for most pelvic indications.
    • Maximum bulk / length — divide the short gastric arteries connecting the gastroepiploic to the stomach high against the greater curvature. Yields the maximum flap but takes longer and risks gastric injury.
  4. Use a bipolar vessel sealer (LigaSure, Enseal, or equivalent) — the omentum has considerable vascular supply and unexpectedly vigorous bleeding without energy-based sealing.
  5. Confirm the flap reaches tension-free to the target before committing to division.
  6. Deliver the flap into the pelvis or through a tunnel to the target.
  7. Tack the flap gently to prevent torsion on the pedicle.

Laparoscopic / Robotic Harvest​

Formerly limited with the da Vinci Si because the omentum tended to remain in the upper abdomen, particularly in Trendelenburg. The da Vinci Xi (and later platforms) enable omental access without re-docking — the boom design allows direct upper-abdominal reach from a pelvic console setup.

  • Trendelenburg is released briefly to allow the omentum to fall back into the upper abdomen for dissection.
  • Robotic vessel sealer or bipolar energy is used to divide the omental attachments.
  • The flap is delivered into the pelvis through the standard working corridors.
  • For BMG ureteroplasty, the omentum is wrapped around the onlay graft as a vascularized backing.

Laparoscopic harvest outcomes — Zaha 2010 reported a 96-patient series with 99% success rate, donor-site complications of only 8.3% (one incisional hernia), and graft survival of 96.8% — significantly less morbidity than open harvest.[5]

Choosing Between Omentum and Rectus Flap​

Prefer omentum when available, because:

  • Lower donor-site morbidity — no abdominal-wall hernia risk, no muscle sacrifice
  • Same incision already open for the index urologic operation
  • Excellent perfusion in radiated or scarred beds
  • Porous structure drains dead space

Prefer rectus (VRAM) when:

  • Pelvic floor reconstruction after APR / extensive exenteration — omentum lacks the bulk and structural support for large pelvic floor defects
  • Omentum is absent (prior omentectomy), scarred, or too short
  • The defect requires a skin paddle (omentum provides tissue coverage only)
  • Previous abdominal surgery has compromised the gastroepiploic arcade

GU Applications​

Fistula Interposition​

The single most common urologic application. The omentum is interposed as a vascularized barrier between repaired bladder / urethra / ureter / rectum and the overlying closure, introducing healthy non-scarred tissue into a compromised field.

Indications span every pelvic fistula:

  • Vesicovaginal fistula — particularly large, radiation-induced, or recurrent
  • Urethrovaginal fistula — interposition between bladder/urethral and vaginal closures
  • Vesicouterine fistula
  • Colovesical fistula
  • Rectourethral fistula (with concurrent gracilis commonly)
  • Urosymphyseal fistula — preferred first-line flap per 2026 comparative series (Escandón): omental 90-day sepsis 3% vs VRAM 27%, with lower fistula recurrence[see VRAM article]
  • Ureterovaginal / ureterocolic fistula

The 2026 Cochrane review of VVF surgical interventions notes omentum, sigmoid taenia epiploicae, and peritoneal flaps as the common transabdominal interposition options (Martius preferred transvaginally).[6]

Robot-assisted extravesical VVF repair with laparoscopically mobilized omental flap interposition (Watts 2017) achieves same-day or next-day discharge with no fistula recurrence at 3 months — illustrating the contemporary minimally-invasive workflow.[7]

For rectourethral fistula, an abdominoperineal approach with omentoplasty achieved good results in all 9 patients in a Trippitelli 1985 series, particularly for complex or recurrent fistulae.[8]

Buccal Mucosa Graft Ureteroplasty — Vascularized Backing​

The signature robotic-era omental indication. When a buccal mucosal graft is laid as an onlay patch or tube to reconstruct a ureteral stricture, it is dependent on the recipient bed for inosculation. The omentum is wrapped around the BMG-ureter construct, and:

  • Drives neovascularization into the graft
  • Drains any fluid accumulation beneath the graft (urine leak, hematoma, seroma) through its porous structure — preventing dead space that would otherwise strand the graft
  • Protects the ureter from late scarring by interposing healthy tissue between the ureter and surrounding retroperitoneal fat / psoas

Without vascularized backing, BMG ureteroplasty success falls; with omental wrap, published series report 75–100% success rates.

Ureterolysis in Retroperitoneal Fibrosis​

For bilateral retroperitoneal fibrosis (Ormond's disease or secondary RPF), the goal is to mobilize the encased ureter into the peritoneal cavity and wrap it in healthy tissue to prevent re-encasement. Technique:

  1. Laparotomy or robotic access.
  2. Dissect the ureter out of the fibrotic plaque with careful identification (caution with the gonadal vessels and iliac bifurcation landmarks).
  3. Transpose the ureter intraperitoneally.
  4. Divide the omentum vertically in the midline to create two flaps — right and left, each on its own gastroepiploic pedicle.
  5. Wrap each ureter in its respective omental flap — the omentum circumferentially envelopes the ureter preventing re-scarring.

Alternative: if unilateral, a single pedicled omental flap suffices.

Both laparoscopic ureterolysis with omental wrap (Fong 2006; Stein 2010) report 100% symptomatic and radiographic success at median 16–18 months, with the omentum passed through a mesenteric window to reach the retroperitoneum.[9][10]

Complex Urethroplasty Support​

Laparoscopic omentoplasty combined with perineal anastomotic urethroplasty for complex and redo pelvic-fracture urethral defects (Kulkarni 2015) achieved a 93.3% success rate (14/15 patients) at median 18-month follow-up — the omentum envelops the anastomosis and fills perineal dead space.[11]

Bladder-Neck Reconstruction and Tissue-Engineered Bladder​

  • Bladder-neck reconstruction in exstrophy / epispadias — Diamond 1986 reported wrapping the Young-Dees tube with omentum during bladder-neck reconstruction; 85% dryness in exstrophy patients also undergoing augmentation cystoplasty.[12]
  • Tissue-engineered bladder constructs — in the Atala 2006 Lancet landmark, autologous bladder constructs wrapped in omentum after implantation showed the greatest improvements in leak-point pressure (56% decrease), volume (1.58-fold increase), and compliance (2.79-fold increase) vs. unwrapped constructs.[13]

Neovaginal Reconstruction — Omental J-Flap with STSG​

A well-established technique after pelvic exenteration. The omentum is fashioned into a cylinder, sutured to the introitus, and lined with split-thickness skin graft. In a 20-patient series, all flaps and grafts remained viable with no pelvic infection, fistula, or hernia, and ~80% had potential for sexual function.[14][15] The 2025 NCCN Cervical Cancer guidelines list STSG with omental J-flap alongside myocutaneous flaps as neovaginal-reconstruction options for all types of pelvic exenteration.[16]

Pelvic Dead-Space Obliteration​

After radical cystectomy, radical cystoprostatectomy, pelvic exenteration, or APR, the pelvic basin is a non-collapsible cavity prone to fluid collections, bowel prolapse, and fistula formation. The omentum is brought down to fill the basin:

  • Reduces dead space that would otherwise fill with serum or urine
  • Introduces non-irradiated tissue into a radiated field
  • Cushions the small bowel away from the pelvic floor
  • Can be combined with a peritoneal closure to restore the pelvic diaphragm

Single-center data support benefit: pelvic infection was significantly reduced in 27 patients receiving omental flaps (Miyamoto 2016),[17] and a 70-patient series found major pelvic complications in 21% with omentum vs. 61% without (p < 0.05) (Hultman 2010).[18]

A counterpoint deserves explicit mention: a large NSQIP analysis of 3,063 APR patients (Welten 2019) found omental-flap creation independently associated with increased organ-space infection (10.4% vs. 6.5%; OR 1.72, p = 0.04), with no significant difference in other wound complications.[19] The discrepancy with single-center data may reflect selection bias (omentum used in more complex or radiated cases) and technique variability.

When combined with VRAM, the omentum provides synergistic benefit: adjuvant omental wrap combined with VRAM reduces perineal dehiscence in pelvic-cancer reconstructions (Campbell 2011).[20]

Radiation-Wound Revascularization​

The omentum is uniquely effective in irradiated fields — its rich vascular supply effectively "dilutes" the hypovascular radiated bed with healthy tissue, supporting subsequent wound healing and graft take. Elevating the small intestines out of the true pelvis with an omental flap also enables high-dose brachytherapy with less radiation enteritis.[2]

Pubic Osteomyelitis / Urosymphyseal Fistula​

For urosymphyseal fistula — typically after pelvic radiation + prostatectomy with osteomyelitis of the pubic bone — omental flap interposition fills the debrided pubic-bone cavity and covers the urinary repair. Emerging comparative data favor omentum over VRAM for this indication.

Buccal-Mucosa-Based Fistula Repair​

Occasionally omental coverage is used as the final layer over a buccal-mucosal onlay closure of a complex fistula.

Outcomes​

Outcomes vary by indication; omentum is the common denominator in high-success-rate pelvic reconstructions.

  • BMG ureteroplasty with omental wrap — 75–100% success in published series
  • Complex VVF — omentum + layered closure cure rates approach 90–95%
  • Urosymphyseal fistula — 90-day sepsis 3% (vs. 27% VRAM); lower fistula recurrence than VRAM or primary repair[21]
  • Ureterolysis in RPF — excellent long-term patency with omental wrap; prevents re-encasement

Donor-Site Complications — Hultman 2002 25-Year Series​

The largest single-institution donor-site complication series (135 omental flaps, 1975–2000) reported:[22]

ComplicationIncidence
Overall donor-site complications18.5% (25/135)
Abdominal-wall infection6.7% (9/135)
Fascial dehiscence5.9% (8/135)
Symptomatic hernia5.9% (8/135)
Unplanned re-exploration4.4% (6/135)
Postoperative ileus2.2% (3/135)
GI hemorrhage1.5% (2/135)
Partial flap loss8.1% (11/135)
Total flap loss2.2% (3/135)
Mortality5.9% (8/135)

Risk factors for donor-site complications include pedicled flaps (vs. free transfer), mediastinitis, advanced age, and pulmonary failure. Of 53 patients with prior abdominal surgery, 26 required extensive adhesiolysis and 4 sustained enterotomies.[22] Laparoscopic harvest (Zaha) lowers complication rates substantially (~8.3%), confirming the value of minimally-invasive harvest where feasible.[5]

Limitations​

  • Unavailable / scarred omentum — prior omentectomy (gastric, gynecologic, or colorectal surgery), omental adhesions, or radiation-induced fibrosis may render the flap inadequate. Assess preoperatively via history and intraoperatively on exposure.
  • Short omentum — small body habitus, prior obesity with intervening weight loss, or adhesive tethering may limit reach. Measure before committing.
  • No skin paddle — omentum is tissue coverage only; external defects still need a skin graft or an additional skin flap.
  • Bulk — sufficient for fistula interposition and BMG backing, but not sufficient as a primary reconstructive flap for large pelvic floor defects (VRAM, gracilis, IGAM preferred there).
  • Gastric injury risk — maximum-bulk harvest requires dissecting the short gastric vessels close to the stomach. Vigilance is essential.
  • Pedicle torsion — the omentum can twist on its gastroepiploic pedicle if not tacked. Strangulation produces flap loss.

Choose Omentum vs Alternative​

ScenarioPreferred
Any abdominally-approached fistula with omentum availableOmentum
BMG ureteroplasty backingOmentum (definitive — do not substitute)
Unilateral or bilateral ureterolysis in RPFOmentum (bilateral division for both sides)
Pelvic dead-space obliteration in non-exenteration cystectomyOmentum
Pelvic floor reconstruction after APR / total exenteration with large defectVRAM / gracilis / IGAM (omentum insufficient)
Urosymphyseal fistulaOmentum (per Escandón 2026 comparative data)
Transvaginal VVF repairPeritoneal flap or Martius (omentum not accessible vaginally)
Omentum absent or compromisedVRAM or perivesical fat rotational flap (Hwang 2023, novel alternative for VVF / colovesical fistula / RUF)[23]

Key Takeaways​

  1. Omentum is the first-choice pedicled interposition flap when abdominally accessible — lowest donor-site morbidity of any urologic reconstructive option.
  2. Dual gastroepiploic pedicle — either right or left is adequate for pelvic reach; divide one to mobilize.
  3. Bilateral omental flaps via midline vertical division for bilateral ureterolysis in RPF.
  4. Use a vessel-sealing device (LigaSure or equivalent) — the omentum bleeds vigorously without energy control.
  5. Transverse-colon-reflection release is faster; short-gastric release gives more bulk when needed.
  6. The porous structure is the point — omentum drains dead space, which is why it is the definitive backing for BMG ureteroplasty (75–100% success with wrap).
  7. Robotic harvest became easier with the da Vinci Xi; Trendelenburg release allows upper-abdominal dissection without re-docking.
  8. Urosymphyseal fistula — recent comparative evidence favors omentum over VRAM (3% vs 27% 90-day sepsis; lower recurrence).
  9. Not a primary flap for large pelvic floor defects — omentum supports reconstruction, it does not replace muscle-based flaps (VRAM, gracilis, IGAM) for major perineal / exenteration defects.
  10. Prior omentectomy, short omentum, or adhesive fibrosis may preclude use — always assess preoperatively and confirm on exposure.

References​

1. Turner-Warwick R. "The Use of the Omental Pedicle Graft in Urinary Tract Reconstruction." J Urol. 1976;116(3):341–347. doi:10.1016/s0022-5347(17)58809-6

2. Logmans A, Trimbos JB, van Lent M. "The Omentoplasty: A Neglected Ally in Gynecologic Surgery." Eur J Obstet Gynecol Reprod Biol. 1995;58(2):167–171. doi:10.1016/0028-2243(94)01994-0

3. Topor B, Acland RD, Kolodko V, Galandiuk S. "Omental Transposition for Low Pelvic Anastomoses." Am J Surg. 2001;182(5):460–464. doi:10.1016/s0002-9610(01)00764-4

4. Fix RJ, Vasconez LO. "Use of the Omentum in Chest-Wall Reconstruction." Surg Clin North Am. 1989;69(5):1029–1046. doi:10.1016/s0039-6109(16)44936-4

5. Zaha H, Inamine S. "Laparoscopically Harvested Omental Flap: Results for 96 Patients." Surg Endosc. 2010;24(1):103–107. doi:10.1007/s00464-009-0533-0

6. Okada Y, Matsushita T, Hasegawa T, et al. "Surgical Interventions for Treating Vesicovaginal Fistula in Women." Cochrane Database Syst Rev. 2026;1:CD015413. doi:10.1002/14651858.CD015413

7. Watts KL, Ho R, Ghavamian R, Abraham N. "Robot-Assisted Extravesical Vesicovaginal Fistula Repair Utilizing Laparoscopically Mobilized Omental Flap Interposition." Int Urogynecol J. 2017;28(4):641–644. doi:10.1007/s00192-016-3218-y

8. Trippitelli A, Barbagli G, Lenzi R, Fiorelli C, Masini GC. "Surgical Treatment of Rectourethral Fistulae." Eur Urol. 1985;11(6):388–391. doi:10.1159/000472547

9. Fong BC, Porter JR. "Laparoscopic Ureterolysis: Technical Alternatives." J Endourol. 2006;20(10):820–822. doi:10.1089/end.2006.20.820

10. Stein RJ, Patel NS, Quinn K, et al. "Laparoscopic Ureterolysis With Omental Wrap for Idiopathic Retroperitoneal Fibrosis." BJU Int. 2010;106(5):703–707. doi:10.1111/j.1464-410X.2009.09186.x

11. Kulkarni SB, Barbagli G, Joshi PM, et al. "Laparoscopic Omentoplasty to Support Anastomotic Urethroplasty in Complex and Redo Pelvic Fracture Urethral Defects." Urology. 2015;85(5):1200–1205. doi:10.1016/j.urology.2014.12.055

12. Diamond DA, Ransley PG. "Bladder Neck Reconstruction With Omentum, Silicone and Augmentation Cystoplasty — a Preliminary Report." J Urol. 1986;136(1 Pt 2):252–255. doi:10.1016/s0022-5347(17)44831-2

13. Atala A, Bauer SB, Soker S, Yoo JJ, Retik AB. "Tissue-Engineered Autologous Bladders for Patients Needing Cystoplasty." Lancet. 2006;367(9518):1241–1246. doi:10.1016/S0140-6736(06)68438-9

14. Kusiak JF, Rosenblum NG. "Neovaginal Reconstruction After Exenteration Using an Omental Flap and Split-Thickness Skin Graft." Plast Reconstr Surg. 1996;97(4):775–781; discussion 782–783. doi:10.1097/00006534-199604000-00013

15. Wheeless CR. "Neovagina Constructed From an Omental J Flap and a Split Thickness Skin Graft." Gynecol Oncol. 1989;35(2):224–226. doi:10.1016/0090-8258(89)90048-6

16. National Comprehensive Cancer Network. "Cervical Cancer (NCCN Guidelines)." Updated 2025-11-10.

17. Miyamoto Y, Akiyama T, Sakamoto Y, et al. "Omental Flap After Pelvic Exenteration for Pelvic Cancer." Surg Today. 2016;46(12):1471–1475. doi:10.1007/s00595-016-1348-y

18. Hultman CS, Sherrill MA, Halvorson EG, et al. "Utility of the Omentum in Pelvic Floor Reconstruction Following Resection of Anorectal Malignancy: Patient Selection, Technical Caveats, and Clinical Outcomes." Ann Plast Surg. 2010;64(5):559–562. doi:10.1097/SAP.0b013e3181ce3947

19. Welten VM, Fields AC, Lu P, et al. "Omental Flaps in Patients Undergoing Abdominoperineal Resection for Rectal Cancer." Int J Colorectal Dis. 2019;34(7):1227–1232. doi:10.1007/s00384-019-03319-w

20. Campbell CA, Butler CE. "Use of Adjuvant Techniques Improves Surgical Outcomes of Complex Vertical Rectus Abdominis Myocutaneous Flap Reconstructions of Pelvic Cancer Defects." Plast Reconstr Surg. 2011;128(2):447–458. doi:10.1097/PRS.0b013e31821e6fd2

21. Escandón JM, Kreutz-Rodrigues L, Fadel AE, et al. "Optimizing Flap Selection for Urosymphyseal Fistula Repair: A Comparative Analysis of Surgical Outcomes." Microsurgery. 2026;46(3):e70197. doi:10.1002/micr.70197

22. Hultman CS, Carlson GW, Losken A, et al. "Utility of the Omentum in the Reconstruction of Complex Extraperitoneal Wounds and Defects: Donor-Site Complications in 135 Patients From 1975 to 2000." Ann Surg. 2002;235(6):782–795. doi:10.1097/00000658-200206000-00005

23. Hwang A, Watson M, Talluri S, Okafor H, Singh A. "A Novel Perivesical Fat Rotational Flap as an Alternative to Omental Interposition in Challenging Urological Reconstruction." Urology. 2023;182:e262–e263. doi:10.1016/j.urology.2023.08.023