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Enterourethroplasty

Enterourethroplasty is the use of intestinal tissue (bowel segments or intestinal mucosa) for urethral reconstruction. The techniques range from full-thickness intestinal flap interposition (tubularized bowel segments on a vascular pedicle) to free mucosal grafts harvested from the colon, rectum, or other gastrointestinal segments. It is a salvage approach for otherwise unsalvageable urethral strictures or defects when conventional techniques (buccal mucosa grafts, skin flaps) have failed or are contraindicated.[1][2][3]

For the graft-material framing of rectal mucosa (history, harvest-technique comparison, BMG-versus-RMG selection), see Grafts in GU Reconstruction → Rectal Mucosa Graft. For other graft material details, see Buccal Mucosa Graft. For appendiceal use in upper-tract reconstruction, see Appendiceal / Ileal Onlay Ureteroplasty. For catheterizable-channel applications, see Continent Catheterizable Channels. For metabolic management, see Mucus Management, Vitamin B12 Supplementation, and Urinary Acidifiers & Alkalinizers.

Clinical Context​

Published salvage approaches include colonic mucosal grafting, full-thickness bowel interposition and microvascular intestinal transfer.[1][2][4] These operations differ substantially in donor morbidity, tissue support and urinary contact.[1][2][4]

Types of Enterourethroplasty​

1. Full-thickness intestinal flap interposition (Mundy / Andrich technique)​

A full-thickness segment of bowel on its mesenteric vascular pedicle is harvested, tailored to an appropriate urethral caliber, and interposed as a tubular neourethra.[1]

  • Bowel segments. Ileum, stomach, right colon, or (preferably) sigmoid colon were used.
  • Preferred segment. Mundy and Andrich preferred sigmoid colon.
  • Graft dimensions. The flap averaged 8 cm in length and was tailored to 26–30 Fr caliber.
  • Route. The neourethra follows the normal perineal route or a direct transpubic route through a trench cut in the superior pubic ramus.
  • Anastomosis. The proximal end is sutured to the prostatic stump and the distal end to the distal bulbar or proximal pendulous urethra.

Outcomes (Mundy / Andrich, 11 patients over 10 years, otherwise unsalvageable bulbomembranous strictures or defects):[1]

  • 3/11 developed proximal anastomotic contracture (1 managed with dilation, 2 required revision)
  • 2/11 developed stones in the gut segment (1 caused irreparable damage to the neourethra during removal)
  • The authors described the results as otherwise satisfactory

2. Colonic mucosal graft urethroplasty (Xu et al.)​

The colonic mucosal series below are from Yue-Min Xu's group. Xu's colonic mucosal series used free grafts harvested from the colon (typically sigmoid); the initial seven clinical grafts were tubularized over 18–22 Fr stents.[4][5][6][7] The EAU 2026 guideline strongly recommends against single-stage tubularized grafts because complications are more frequent than with onlay grafts.[24]

  • Graft length. 10–20 cm (mean 13–15 cm), which may provide a larger single graft than one oral donor site[5][4]
  • Harvest. Historically required sigmoid colectomy for retrieval, the major limitation of the technique[3][8]
StudynMean Graft LengthSuccessFollow-upKey Findings
Xu 2003 (initial)[5]713.1 cm6/7 without reported meatal stenosis; no formal success proportionmean 8.5 mo (3–18)Metaplasia at 12 weeks was observed in the companion dog experiment
Xu 2004 (expanded)[7]16median 13 cmNo formal success proportion reported in the cited abstract6–33 moOne meatal stenosis required reoperation; a separate verumontanum hyperplasia required colliculectomy; the other patients voided with Qmax >15 mL/s
Xu 2007 (comparative)[6]65 mixed repairs, including 28 colonic grafts—50/65 (76.9%) overallmean 4.8 yrOutcomes include mucosal grafts, skin flaps and staged procedures
Xu 2009 (long-term)[4]35 followed of 36 operated15.1 cm30/35 (85.7%) normal voiding without any postoperative proceduremean 53.6 moMost common complications: meatal and anastomotic stenosis

3. Rectal mucosal graft urethroplasty (Vanni / Palmer / Zhao)​

Minimally invasive transanal harvest of rectal mucosa has been described to avoid the morbidity of colonic resection.[8][9][10]

Harvest techniques:

  • Transanal endoscopic microsurgery (TEM). Introduced clinically in 2013 and reported by Palmer in 2016; rectal mucosa harvested endoscopically through a transanal platform.[8]
  • Robotic transanal minimally invasive surgery (R-TAMIS). Howard and colleagues described submucosal hydrodissection in six urethral and one vaginal repair and confirmed donor-site hemostasis by flexible sigmoidoscopy; the series did not compare harvest platforms.[10]
  • Single-port endorobotic harvest. Ozgur and colleagues described submucosal lift followed by dissection beginning 2 cm proximal to the sphincter complex.[11] In a separate single-port report, Emrich Accioly and colleagues began posterior submucosal dissection proximal to the dentate line, obtained hemostasis, and thinned the graft before urethroplasty.[26]
StudynGraft LengthSuccessFollow-upKey Findings
Palmer 2016 (initial TEM)[8]4median stricture length 13.5 cm3/4 without in-graft recurrence (failure defined as inability to pass a 16 Fr cystoscope)median 18 moFirst TEM rectal mucosa harvest for urethroplasty; no colorectal complications
Granieri 2019 (TURNS multi-institutional)[9]13mean 10.6 cm11/13 (85%) without reported stricture recurrence across mixed onlay/two-stage repairsmedian 13.5 mo69% had prior failed BMG; 46% lichen sclerosus; bowel safety assessed only in small cohorts
Howard 2019 (R-TAMIS)[10]6 urethral + 1 vaginalmean 11.4 × 3.0 cm (all 7 grafts)All 7 grafts took; urethral patency not separately reportedmedian 17 mo (all 7)First robotic rectal mucosa harvest; patients with prior BMG self-reported less pain than after their prior BMG harvest
Ozgur 2023 (single-port endorobotic)[11]2———Technical report of two harvests; no harvest-related complication stated for one patient

4. Appendiceal interposition urethroplasty​

The vermiform appendix has been used as a pedicled or free vascularized flap for urethral substitution, particularly for posterior urethral defects. Human experience is limited to case reports and small series; the posterior urethral experience cited from Büyükünal 1995 is a rabbit experiment.[12][13][14][15][16]

  • Anatomy and tradeoffs. Natural tube structure with mucosal lining, muscular wall, an identifiable vascular pedicle (appendicular artery); no hair; rich vascularization; potential donor-site morbidity requiring separate assessment.[12][14]
  • Applications. Posterior urethral reconstruction after PFUI, penile or phallus reconstruction in selected cases of severe fibrosis, and catheterizable channels (Mitrofanoff principle).[13][14][15][17]
  • Technique. Appendix mobilized on its mesenteric pedicle, transposed to the perineum, and anastomosed between the prostatic urethra and bulbar or penile urethra. Omentum may be wrapped around the anastomosis.[13]
  • Outcomes. Reports are limited to small series. Aggarwal reported normal micturition and continence in two boys with PFUI at 1–3 years; one required a single dilation after reconstruction. Koshima used free vascularized appendix transfer with microvascular anastomosis, combined with a radial forearm osteocutaneous flap, for penile urethral reconstruction in 2 patients with severe fibrosis and reported successful results.[13][14]

5. Jejunal free flap urethroplasty (Bales / Gottlieb)​

A segment of jejunum harvested on its vascular pedicle, plicated to an appropriate urethral caliber, and transferred as a free flap with microvascular anastomosis to recipient vessels in the perineum.[2]

  • Requires a multidisciplinary team (reconstructive urologist and microsurgeon)
  • Both patients in the initial series (n = 2) had satisfactory functional and cosmetic outcomes at short follow-up, with patent urethral lumens and standing voiding[2]
  • Selection. Bales and colleagues described jejunal free transfer in two cases and proposed it as a salvage option when conventional grafts or local flaps have failed or are contraindicated.[2]

Indications​

Enterourethroplasty has been used when conventional graft materials are unavailable, insufficient, or contraindicated:[1][3][8][9]

  • Panurethral or very long-segment strictures (>10–15 cm) may require more than one graft or technique. Intestinal mucosa is a selected option when adequate oral mucosa and penile skin are unavailable, unsuitable, or undesired.[24][25]
  • Prior failed buccal-graft urethroplasty. Nine of 13 TURNS patients (69%) had a failed BMG repair; remaining oral donor tissue should be assessed separately before selecting bowel mucosa.[9][25]
  • Oral pathology precluding buccal harvest: oral lichen planus, submucous fibrosis, heavy tobacco use, prior oral radiation[3]
  • Otherwise unsalvageable bulbomembranous strictures or urethral defects after trauma[1]
  • Failed multiple prior urethroplasties (patients averaged 2.5–3 prior failed repairs in colonic-mucosa series)[4][5]
  • Strictures after gender-affirming phalloplasty. Rectal mucosal grafting has been described for these repairs.[9][10] In the TURNS cohort, three patients had strictures at the fixed-urethra–neophallus junction extending into the neophallus.[9] The EAU 2026 guideline strongly recommends against endoscopic incision or urethroplasty within six months after neophalloplasty and weakly recommends staged urethroplasty for strictures within the neophallic urethra.[28]

Properties of Intestinal Mucosa for Urethral Reconstruction​

PropertyColonic / Rectal MucosaBuccal Mucosa
Reported graft lengths10–20 cm for colonic grafts in Xu 2009[4]; 3–16 cm for rectal grafts in TURNS[9], and a 21 × 3 cm rectal graft in one single-port case[26]Cheek-only grafts ranged from 2–13 cm in a 12-patient series[27]
Epithelial typeColumnar; 12-week transitional metaplasia is animal evidenceStratified squamous (non-keratinized)
Graft thicknessThin mucosal layerThick, resilient
Harvest morbidityColectomy is more invasive; transanal approaches have encouraging but small safety cohortsLow (oral pain, numbness)
Mucus productionPresent (may cause postvoid dribbling)Minimal
Stone formation riskReported in bowel segmentsNot an intrinsic mucus-secreting graft; stones can still occur with obstruction, infection or foreign material
Metabolic complicationsMetabolic effects of urinary contact with bowel are described mainly for reservoirs and diversions[19][20]None
AvailabilityLimited by safe harvest, bowel health and donor morbidityLimited by oral cavity size and tissue quality

Histological Adaptation​

In Xu’s 10-dog experiment, colonic mucosa demonstrated metaplastic transformation after urethral replacement:[5][18]

  • At 8 weeks: colonic plicae and unilaminar cylindric epithelium still visible
  • By 12 weeks: plicae and cylindric epithelium disappear, replaced by metaplastic transitional epithelium covering most of the urethral mucosa
  • Urodynamics in the nine dogs without stricture showed no significant change in maximum urethral pressure before and after the operation (p > 0.05)

Choice of Intestinal Segment​

SegmentAdvantagesDisadvantagesBest Application
Sigmoid colon (full-thickness preferred)Proximity to perineum; robust blood supply; appropriate caliberRequires laparotomy; mucus production; stone riskFull-thickness interposition for bulbomembranous defects[1]
Colonic mucosa (free graft)Large graft (10–20 cm); selected long-segment feasibility dataHistorically required colectomy for harvestLong-segment / pan-urethral strictures[4][6]
Rectal mucosa (free graft)Minimally invasive harvest (TEM / R-TAMIS); no colectomy; large graft (3–16 cm in the TURNS cohort); bowel safety assessed only in small cohorts[9]Limited long-term data; newer techniqueAlternative to BMG when oral mucosa unavailable[8][9][10]
IleumWell-vascularized; familiar to urologistsTerminal ileal resection can cause B12 deficiency, diarrhea and cholelithiasis; urine-exposed ileum produces mucus. Rates after short urethral interposition are unquantifiedRarely used for urethroplasty; more common for bladder augmentation[19][20]
StomachDecreased urinary pH and no mucus problems were reported in 22 adults after gastric bladder augmentation or reservoir reconstruction at mean 9.8-month follow-up[22]Hypochloremic alkalosis in 2/22 in that early cohort; hematuria-dysuria in 7/29 and reservoir malignancy in 3/29 in a separate long-term gastrocystoplasty/reservoir cohortCastellan and colleagues do not recommend gastric segments for lower urinary tract reconstruction[21][22]
AppendixNatural tube; muscular wall; consistent pedicle; no hairLimited length; single-use organ; not always availablePosterior urethral defects; catheterizable channels[13][14][15]

Complications Specific to Enterourethroplasty​

Beyond the standard urethroplasty complications, enterourethroplasty carries unique risks related to intestinal tissue.[1][19][20]

Urethral / reconstructive​

  • Anastomotic contracture. 27% in the Mundy series (3/11), the most common complication of full-thickness interposition[1]
  • Stone formation in the gut segment. Mucus production by intestinal epithelium serves as a nidus; reported in 2/11 patients (Mundy)[1]
  • Meatal and anastomotic stenosis. These were the most common complications of colonic mucosal graft urethroplasty. Meatal stenosis occurred in 1 of 16 patients in Xu 2004, and meatal, bulbar or bulbomembranous and anastomotic stenoses together occurred in 5 of 35 evaluated patients in Xu 2009.[4][7]
  • Graft sacculation / pseudodiverticulum. Xu reported 2/65 after mixed substitution procedures. A separate five-patient rectal-graft series reported one small diverticulum; its authors noted that thin rectal mucosa needs adequate tissue support.[6][30]
  • Mucus production. May cause postvoid dribbling and serve as a nidus for infection and stone formation[1][19]

Bowel-related / metabolic​

  • Metabolic imbalance. In urinary reservoirs or diversions, ileal or colonic segments can cause hyperchloremic metabolic acidosis, while gastric segments can cause hypochloremic alkalosis.[19][20][22] Risk varies with bowel surface area and urine-contact time.[19][20][22]
  • Vitamin B12 deficiency. Assess whether and how much terminal ileum was removed, baseline absorption and nutritional status; there is no validated universal 10-cm cutoff for these operations. Use the linked B12 companion for risk-based surveillance.[20]
  • Cholelithiasis. Derangements in bile salt metabolism with ileal resection.[20]
  • Diarrhea. Secretory-osmotic diarrhea with ileal resection and loss of ileocecal valve.[20]
  • Malignancy. Castellan 2012 reported 3 malignancies in 29 patients (10.3%) undergoing gastric segment lower-urinary-tract reconstruction at 11–14 yr, all of whom died of metastasis. The authors recommended against using gastric segments for lower urinary tract reconstruction.[21]

Contraindications to gastric segments​

After their reservoir or augmentation cohort, Castellan and colleagues recommended against gastric segments for lower urinary tract reconstruction:[21]

  • 51.7% complication rate (15/29 patients)[21]
  • Hematuria-dysuria syndrome in 7 patients (intractable in 1)
  • Reservoir malignancy in 3 of 29 gastric-segment reconstruction patients (10.3%) at 11–14 yr after gastrocystoplasty; all 3 died of metastasis[21]
  • Multiple major reoperations required

Current Role and Future Directions​

The AUA Urethral Stricture Disease Guideline (2023 amendment) states that surgeons should use oral mucosa as the first choice when using grafts .[23] Enterourethroplasty remains a niche salvage technique. For complex anterior strictures, the EAU 2026 guideline strongly recommends offering perineal urethrostomy as a management option.[25] Published intestinal techniques include:

  • Rectal mucosal grafts (TEM or R-TAMIS) provide a large graft without colectomy. The TURNS cohort had 11/13 without recurrence at median 13.5 months and no reported bowel complication, but did report glans dehiscence, fistula and compartment syndrome in 1 patient each. The series are small and short-term.[9]
  • Xu 2009 reported normal voiding without further procedure in 30/35 followed colonic-graft patients at mean 53.6 months.[4] A 2026 multicentre retrospective comparison of one-stage repairs for >10 cm strictures reported normal voiding and urethrogram without reintervention in 59/69 colonic-graft patients at mean 145 months and 184/225 oral-graft patients at mean 58 months; patient overlap with the earlier Xu cohort is possible, and unequal follow-up limits direct efficacy comparison.[4][29] The need for colectomy has limited adoption of colonic grafts.[3][8] The EAU guideline reports a colonic-abdominal fistula in 1/35 patients and advises considering other grafts only when oral mucosa and penile skin are unavailable, unsuitable, or undesired.[4][24]
  • Full-thickness intestinal interposition (Mundy technique) is a last-resort salvage procedure for otherwise unsalvageable bulbomembranous defects.[1]
  • Tissue-engineered grafts are under investigation and may reduce the amount of autologous tissue harvested. The EAU 2026 guideline strongly recommends against autologous tissue-engineered oral mucosa grafts outside a clinical trial and weakly recommends against cell-free grafts after failed urethroplasty, with extensive spongiofibrosis, or for strictures >4 cm.[3][24]

Videos​

Enterourethroplasty
Operative technique
Rectal Mucosal Graft Urethroplasty
Neupane R, et al. Urology Video Journal 2021 (CC BY 4.0)
Open source videoRead the article

References​

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  2. Bales GT, Kuznetsov DD, Kim HL, Gottlieb LJ. Urethral substitution using an intestinal free flap: a novel approach. J Urol. 2002;168(1):182-4. doi:10.1016/s0022-5347(05)64857-4

  3. Browne BM, Vanni AJ. Use of alternative techniques and grafts in urethroplasty. Urol Clin North Am. 2017;44(1):127-140. doi:10.1016/j.ucl.2016.08.003.

  4. Xu YM, Qiao Y, Sa YL, et al. Urethral reconstruction using colonic mucosa graft for complex strictures. J Urol. 2009;182(3):1040-3. doi:10.1016/j.juro.2009.05.030.

  5. Xu YM, Qiao Y, Sa YL, et al. One-stage urethral reconstruction using colonic mucosa graft: an experimental and clinical study. World J Gastroenterol. 2003;9(2):381-4. doi:10.3748/wjg.v9.i2.381.

  6. Xu YM, Qiao Y, Sa YL, et al. Substitution urethroplasty of complex and long-segment urethral strictures: a rationale for procedure selection. Eur Urol. 2007;51(4):1093-8; discussion 1098-9. doi:10.1016/j.eururo.2006.11.039.

  7. Xu YM, Qiao Y, Sa YL, et al. 1-Stage urethral reconstruction using colonic mucosa graft for the treatment of a long complex urethral stricture. J Urol. 2004;171(1):220-3; discussion 223. doi:10.1097/01.ju.0000094810.60093.bc.

  8. Palmer DA, Marcello PW, Zinman LN, Vanni AJ. Urethral reconstruction with rectal mucosa graft onlay: a novel, minimally invasive technique. J Urol. 2016;196(3):782-6. doi:10.1016/j.juro.2016.03.002.

  9. Granieri MA, Zhao LC, Breyer BN, et al. Multi-institutional outcomes of minimally invasive harvest of rectal mucosa graft for anterior urethral reconstruction. J Urol. 2019;201(6):1164-1170. doi:10.1097/JU.0000000000000087.

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  17. Sheldon CA, Gilbert A. Use of the appendix for urethral reconstruction in children with congenital anomalies of the bladder. Surgery. 1992;112(4):805-11; discussion 811-2. PMID 1411954

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  20. Steiner MS, Morton RA. Nutritional and gastrointestinal complications of the use of bowel segments in the lower urinary tract. Urol Clin North Am. 1991;18(4):743-54. doi:10.1016/s0094-0143(21)00375-x

  21. Castellan M, Gosalbez R, Bar-Yosef Y, Labbie A. Complications after use of gastric segments for lower urinary tract reconstruction. J Urol. 2012;187(5):1823-7. doi:10.1016/j.juro.2011.12.105.

  22. Singla A, Galloway N. Early experience with the use of gastric segment in lower urinary tract reconstruction in adult patient population. Urology. 1997;50(4):630-5. doi:10.1016/S0090-4295(97)00253-7.

  23. 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.

  24. European Association of Urology. EAU Guidelines on Urethral Strictures: Tissue Transfer. EAU Guidelines Office; 2026. Guideline chapter.

  25. European Association of Urology. EAU Guidelines on Urethral Strictures: Disease Management in Males. EAU Guidelines Office; 2026. Guideline chapter.

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  27. Kamp S, Knoll T, Osman M, Häcker A, Michel MS, Alken P. "Donor-site morbidity in buccal mucosa urethroplasty: lower lip or inner cheek?" BJU Int. 2005;96(4):619–623. doi:10.1111/j.1464-410X.2005.05695.x

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  30. Monn MF, Waters JA, Mellon MJ. "Use of rectal mucosal grafts in substitution urethroplasty: an early series." Transl Androl Urol. 2018;7(6):907-911. doi:10.21037/tau.2018.10.12