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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.

Historical Context​

Colonic mucosa grafts for substitution urethroplasty were first described by Igor A. Thyrmos in 1902.[4] The technique remained largely dormant for decades due to the morbidity of bowel harvest (formal colonic resection) and the success of simpler alternatives. Interest was revived in the late 1990s and 2000s by Xu et al. in China (colonic mucosal grafts), Mundy and Andrich in the UK (full-thickness intestinal flap interposition), and Bales / Gottlieb (jejunal free flap with microvascular anastomosis).[1][2][5][6]

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.[5][6][7][8]

  • Graft length — 10–20 cm (mean 13–15 cm), far exceeding what is available from buccal mucosa
  • Harvest — historically required sigmoid colectomy for retrieval, the major limitation of the technique[3][9]
StudynMean Graft LengthSuccessFollow-upKey Findings
Xu 2003 (initial)[6]713.1 cm86% (6/7)8.5 moColonic mucosa undergoes metaplastic change to transitional epithelium by 12 weeks
Xu 2004 (expanded)[8]1613 cm94% (15/16)6–33 mo1 meatal stenosis; Qmax >15 mL/s in all successful cases
Xu 2007 (comparative)[7]28 colonic—77% overall4.8 yrColonic mucosa feasible for pan-urethral and multi-segment strictures
Xu 2009 (long-term)[5]3615.1 cm85.7%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.[9][10][11]

Harvest techniques:

  • Transanal endoscopic microsurgery (TEM) — first described by Palmer 2013 at Lahey Hospital; rectal mucosa harvested endoscopically through a transanal platform.[9]
  • Robotic transanal minimally invasive surgery (R-TAMIS) — described by Howard / Zhao; robotic platform for more precise submucosal dissection, allowing larger grafts.[11]
  • Single-port endorobotic harvest — Ozgur 2023; single-port robotic platform with submucosal hydrodissection for precise mucosal harvest.[12]
StudynGraft LengthSuccessFollow-upKey Findings
Palmer 2016 (initial TEM)[9]4median 13.5 cm75% (3/4)18 moFirst TEM rectal mucosa harvest for urethroplasty; no colorectal complications
Granieri 2019 (TURNS multi-institutional)[10]13median 10.6 cm85% (11/13)13.5 mo69% had prior failed BMG; 46% lichen sclerosus; no bowel complications
Howard 2019 (R-TAMIS)[11]6 (+ 1 vaginal)11.4 × 3.0 cm100% (all grafts took)17 moFirst robotic rectal mucosa harvest; less reported pain than prior BMG harvest
Ozgur 2023 (single-port endorobotic)[12]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.[13][14][15][16][17]

  • Advantages — natural tube structure with mucosal lining, muscular wall, consistent vascular pedicle (appendicular artery); no hair; rich vascularization; minimal donor-site morbidity.[13][15]
  • Applications — posterior urethral reconstruction after PFUI, phalloplasty urethral reconstruction, and catheterizable channels (Mitrofanoff principle).[14][16][17][18]
  • 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.[14]
  • 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.[14][15]

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][9][10]

  • 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)[10]
  • 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)[5][6]
  • Gender-affirming phalloplasty strictures — where long grafts are needed for neophallus urethral reconstruction[10][11]

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 (undergoes metaplasia to transitional epithelium by 12 wk)Stratified squamous (non-keratinized)
Graft thicknessThin mucosal layerThick, resilient
Harvest morbidityHistorically high (colectomy); now minimal with TEM / R-TAMISLow (oral pain, numbness)
Mucus productionPresent (may cause postvoid dribbling)Minimal
Stone formation riskPresent (mucus nidus)Absent
Metabolic complicationsPossible (reabsorption, acid-base) — minimal with short segmentsNone
AvailabilityVirtually unlimitedLimited by oral cavity size

Histological Adaptation​

A key experimental finding — colonic mucosa undergoes metaplastic transformation in the urethral environment:[6][19]

  • 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
  • The continence mechanism is not damaged by colonic mucosal replacement
  • Maximum urethral pressure remains unchanged pre- and post-operatively (p > 0.05)

This metaplastic adaptation suggests colonic mucosa is biologically compatible with the urethral environment and undergoes favorable remodeling over time.

Choice of Intestinal Segment​

SegmentAdvantagesDisadvantagesBest Application
Sigmoid colon (full-thickness preferred)Proximity to perineum; robust blood supply; appropriate caliber; less metabolic disturbance than ileumRequires laparotomy; mucus production; stone riskFull-thickness interposition for bulbomembranous defects[1]
Colonic mucosa (free graft)Large graft (10–20 cm); favorable metaplasia; good long-term resultsHistorically required colectomy for harvestLong-segment / pan-urethral strictures[5][7]
Rectal mucosa (free graft)Minimally invasive harvest (TEM / R-TAMIS); no colectomy; large graft (up to 16 cm); no bowel complicationsLimited long-term data; newer techniqueAlternative to BMG when oral mucosa unavailable[9][10][11]
IleumWell-vascularized; familiar to urologistsMetabolic complications (B12 deficiency, diarrhea, cholelithiasis); mucus productionRarely used for urethroplasty; more common for bladder augmentation[20][21]
StomachAcidic secretion (less infection); less mucusHematuria-dysuria syndrome (51.7%); malignancy risk (10.3%); metabolic alkalosisNo longer recommended for lower urinary tract reconstruction[22][23]
AppendixNatural tube; muscular wall; consistent pedicle; no hair; minimal donor morbidityLimited length; single-use organ; not always availablePosterior urethral defects; catheterizable channels[14][15][16]

Complications Specific to Enterourethroplasty​

Beyond the standard urethroplasty complications, enterourethroplasty carries unique risks related to intestinal tissue.[1][20][21]

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%)[5][7]
  • Graft sacculation / pseudodiverticulum — 3% (Xu)[7]
  • Mucus production — may cause postvoid dribbling and serve as a nidus for infection and stone formation[1][20]

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).[20][21]
  • Vitamin B12 deficiency — risk with ileal resection >10 cm; can cause irreversible neurologic injury if unrecognized.[21]
  • Cholelithiasis — derangements in bile salt metabolism with ileal resection.[21]
  • Diarrhea — secretory-osmotic diarrhea with ileal resection and loss of ileocecal valve.[21]
  • 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.[22]

Contraindications to gastric segments​

Based on Castellan 2012, gastric segments are no longer recommended for lower urinary tract reconstruction:[22]

  • 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.[24] Enterourethroplasty remains a niche salvage technique for specific clinical scenarios:

  • Rectal mucosal grafts (TEM or R-TAMIS) are the most promising evolution — large grafts, minimal harvest morbidity, no bowel complications. The TURNS multi-institutional experience (13 patients, 85% success) supports their safety and efficacy as an alternative when buccal mucosa is unavailable.[10]
  • 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.[5]
  • 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. Pagura EJ, Cavallo JA, Zinman LN, Vanni AJ. Rectal mucosa graft take in staged urethroplasty. Urology. 2019;127:e1-e2. doi:10.1016/j.urology.2019.02.023.
  5. 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.
  6. 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.
  7. 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.
  8. 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.
  9. 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.
  10. 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.
  11. 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.
  12. 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.
  13. 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.
  14. 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.
  15. 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.
  16. 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.
  17. 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.
  18. 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.
  19. 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.
  20. 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.
  21. 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.
  22. 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.
  23. 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.
  24. 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.