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Enterourethroplasty

Enterourethroplasty refers to the use of intestinal tissue (bowel segments or intestinal mucosa) for urethral reconstruction — a spectrum of techniques ranging 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 reserved for patients with 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-vs-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. These operations differ substantially in donor morbidity, tissue support and urinary contact; their outcomes should not be pooled as a single intervention.[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
  • Preferred segment — sigmoid (proximity to the perineum, robust blood supply, appropriate caliber)
  • Graft dimensions — average 8 cm length, tailored to 26–30 Fr caliber
  • Route — normal perineal route or direct transpubic route through a trench cut in the superior pubic ramus
  • Anastomosis — proximal end to the prostatic stump; distal end to the bulbar or proximal pendulous urethra

Outcomes (Mundy / Andrich, 11 patients over 10 years):[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)
  • Otherwise satisfactory results

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

Only the mucosal layer is harvested from the colon (typically sigmoid) and used as a free graft for onlay or tubularized urethroplasty — analogous to BMG urethroplasty but with a much larger graft available.[4][5][6][7]

  • Graft length — 10–20 cm (mean 13–15 cm), which may provide a larger single graft than one oral donor site
  • 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 cm86% (6/7)8.5 moMetaplasia at 12 weeks was observed in the companion dog experiment, not established in these patients
Xu 2004 (expanded)[7]1613 cm94% (15/16)6–33 mo1 meatal stenosis; Qmax >15 mL/s in all successful cases
Xu 2007 (comparative)[6]65 mixed repairs, including 28 colonic grafts—50/65 (76.9%) overall; not colonic-specificmean 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%)53.6 moMost common complications: meatal and anastomotic stenosis

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

The most significant modern evolution — minimally invasive transanal harvest of rectal mucosa 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) — described by Howard / Zhao; robotic platform for more precise submucosal dissection, allowing larger grafts.[10]
  • Single-port endorobotic harvest — Ozgur 2023; single-port robotic platform with submucosal hydrodissection for precise mucosal harvest.[11]
StudynGraft LengthSuccessFollow-upKey Findings
Palmer 2016 (initial TEM)[8]4median 13.5 cm75% (3/4)18 moFirst TEM rectal mucosa harvest for urethroplasty; no colorectal complications
Granieri 2019 (TURNS multi-institutional)[9]13mean 10.6 cm85% (11/13)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 cmAll grafts took; not a standardized urethral-patency endpoint17 moFirst robotic rectal mucosa harvest; less reported pain than prior BMG harvest
Ozgur 2023 (single-port endorobotic)[11]2—no complicationsshort-termFirst single-port robotic rectal mucosal harvest

4. Appendiceal interposition urethroplasty​

The vermiform appendix can be used as a pedicled or free vascularized flap for urethral substitution, particularly for posterior urethral defects.[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, phalloplasty urethral reconstruction, and catheterizable channels (Mitrofanoff principle).[13][15][16][17]
  • Technique — appendix mobilized on its mesenteric pedicle, transposed to the perineum, and anastomosed between the prostatic urethra and bulbar / penile urethra. Omentum may be wrapped around the anastomosis.[13]
  • Outcomes — limited case series with satisfactory results; Aggarwal reported normal micturition and continence in 2 boys with PFUI at 1–3 yr; Koshima used free vascularized appendix transfer with microvascular anastomosis for penile urethral reconstruction in severely fibrosed tissue with good 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 + microsurgeon)
  • Both patients in the initial series had satisfactory functional and cosmetic outcomes with patent urethral lumens and standing voiding
  • Reserved for the most extreme cases where all other options have failed

Indications​

Enterourethroplasty is indicated when conventional graft materials are unavailable, insufficient, or contraindicated:[1][3][8][9]

  • Pan-urethral or very long-segment strictures (>10–15 cm) where buccal mucosa is insufficient in quantity
  • Prior buccal mucosa harvest depleting oral donor sites (69% of rectal-mucosal-graft patients had prior failed BMG urethroplasty)[9]
  • 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]
  • Gender-affirming phalloplasty strictures — where long grafts are needed for neophallus urethral reconstruction[9][10]

Properties of Intestinal Mucosa for Urethral Reconstruction​

PropertyColonic / Rectal MucosaBuccal Mucosa
Maximum graft length15–20 cm (colonic); 10–16 cm (rectal)5–7 cm per cheek
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 complicationsPossible (reabsorption, acid-base) — minimal with short segmentsNone
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 did not demonstrate a significant pressure change; this cannot guarantee continence after human reconstruction
  • Maximum urethral pressure remains unchanged pre- and post-operatively (p > 0.05)

These findings establish experimental feasibility, not a predictable human remodeling interval or proof of superior graft biology.

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 (up to 16 cm); bowel safety assessed only in small cohortsLimited long-term data; newer techniqueAlternative to BMG when oral mucosa unavailable[8][9][10]
IleumWell-vascularized; familiar to urologistsMetabolic complications (B12 deficiency, diarrhea, cholelithiasis); mucus productionRarely used for urethroplasty; more common for bladder augmentation[19][20]
StomachAcidic secretion (less infection); less mucusHematuria-dysuria in 7/29 and reservoir malignancy in 3/29 in one long-term gastrocystoplasty/reservoir cohort; not urethroplasty-specific rates; metabolic alkalosisNo longer recommended 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) — 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 stenosis — most common complication of colonic mucosal graft urethroplasty (5–13%)[4][6]
  • Graft sacculation / pseudodiverticulum — Xu reported 2/65 after mixed substitution procedures; this is not a colonic-graft-specific rate.[6]
  • Mucus production — may cause postvoid dribbling and serve as a nidus for infection and stone formation[1][19]

Bowel-related / metabolic​

  • Metabolic imbalance — bowel mucosa in contact with urine can cause electrolyte disturbances. Severity depends on segment length and contact time (hyperchloremic metabolic acidosis with ileum / colon; hypochloremic alkalosis with stomach).[19][20]
  • 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. This led to the recommendation against using gastric segments for lower urinary tract reconstruction.[21]

Contraindications to gastric segments​

Based on Castellan 2012, the authors recommended against gastric segments for lower urinary tract reconstruction after their reservoir/augmentation cohort; this is not a 29-patient enterourethroplasty series:[21]

  • 51.7% complication rate (15/29 patients)
  • Hematuria-dysuria syndrome in 7 patients (intractable in 1)
  • Malignancy in 3 patients (10.3%) at 11–14 yr — all died of metastasis
  • Multiple major reoperations required

Current Role and Future Directions​

The AUA Urethral Stricture Disease Guideline (2023) recommends oral mucosa as the first-choice graft for substitution urethroplasty.[23] Enterourethroplasty remains a niche salvage technique for specific clinical scenarios:

  • Rectal mucosal grafts (TEM or R-TAMIS) are the most promising evolution — allow a large graft without colectomy. The TURNS cohort had 11/13 without recurrence at median 13.5 months and no observed bowel complication, but did report glans dehiscence, fistula and compartment syndrome. Larger, longer studies are needed to define safety.[9]
  • Colonic mucosal grafts have the most robust long-term data (85.7% success at 53.6 mo) but adoption has been limited by the need for colectomy.[4]
  • Full-thickness intestinal interposition (Mundy technique) remains a true last-resort salvage procedure for otherwise unsalvageable bulbomembranous defects.[1]
  • Tissue engineering using acellular matrices, cell-seeded scaffolds, and 3D bioprinting represents the frontier and may eventually reduce the need for autologous tissue harvest entirely.[3]

Videos​

Enterourethroplasty
Operative technique

References​

  1. Mundy AR, Andrich DE. Entero-urethroplasty for the salvage of bulbo-membranous stricture disease or trauma. BJU Int. 2010;105(12):1716-20. doi:10.1111/j.1464-410X.2009.09005.x.

  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.

  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.

  10. Howard KN, Zhao LC, Weinberg AC, et al. Robotic transanal minimally invasive rectal mucosa harvest. Surg Endosc. 2019;33(10):3478-3483. doi:10.1007/s00464-019-06893-w.

  11. Ozgur I, Justiniano CF, Wood HM, Gorgun E. Single-port endorobotic rectal mucosa harvest for urethral reconstruction. Dis Colon Rectum. 2023;66(2):e54-e57. doi:10.1097/DCR.0000000000002577.

  12. Chen SH, Yeong EK, Tang YB, Chen HC. Free and pedicled appendix transfer for various reconstructive procedures. Ann Plast Surg. 2012;69(6):602-6. doi:10.1097/SAP.0b013e31827475e2.

  13. Aggarwal SK, Goel D, Gupta CR, Ghosh S, Ojha H. The use of pedicled appendix graft for substitution of urethra in recurrent urethral stricture. J Pediatr Surg. 2002;37(2):246-50. doi:10.1053/jpsu.2002.30265.

  14. Koshima I, Inagawa K, Okuyama N, Moriguchi T. Free vascularized appendix transfer for reconstruction of penile urethras with severe fibrosis. Plast Reconstr Surg. 1999;103(3):964-9. doi:10.1097/00006534-199903000-00030.

  15. O'Rourke TK, Gn M, Patel HV, et al. The urologist and the appendix: a review of appendiceal use in genitourinary reconstructive surgery. Urology. 2022;159:10-15. doi:10.1016/j.urology.2021.10.007.

  16. Büyükünal SN, Cerrah A, Dervişoğlu S. Appendix interposition in the treatment of severe posterior urethral injuries. J Urol. 1995;154(2 Pt 2):840-3. doi:10.1097/00005392-199508000-00140.

  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.

  18. Xu Y, Qiao Y, Sa Y, et al. An experimental study of colonic mucosal graft for urethral reconstruction. Chin Med J. 2002;115(8):1163-5.

  19. Martini A, Villari D, Nicita G. Long-term complications arising from bowel interposition in the urinary tract. Int J Surg. 2017;44:278-280. doi:10.1016/j.ijsu.2017.07.030.

  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.

  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.