One-stage urethral reconstruction using colonic mucosa graft: An experimental and clinical study

Minimally invasive robotic ureteral reconstruction using endoscopic submucosal dissection harvested colorectal mucosa graft for ureteral stricture

To evaluate the feasibility and safety of using colorectal mucosal grafts (CMG) harvested via endoscopic submucosal dissection (ESD) for ureteral reconstruction in patients with ureteral stricture. Eight patients with ureteral stricture underwent robotic ureteral reconstruction using CMG harvested by ESD. Preoperative assessments included clinical history, physical examination, and various imaging studies. The ESD procedure was performed with standard precautions to obtain sufficient graft material. Postoperative follow-up involved endoscopic examinations and retrograde pyelograms to assess colorectal complication and ureteral patency. The average age of patients was 44 years, and the median BMI was 24.6 kg/m². The causes of stricture included ureteral stones, urinary tract infections, and ureteral polyps. The median stricture length was 3.5 cm. The average size of the harvested CMG was 4 × 2.4 cm. The success rate of the grafting procedure was 100%, with no gastrointestinal complications observed. Endoscopic examination one week postoperatively revealed well-healed wounds. No recurrent ureteral strictures were noted during a median follow-up period of 5 months. The average glomerular filtration rate (GFR) of the affected kidneys was 61 ml/min. Harvesting CMG via ESD for ureteral reconstruction is feasible and safe, with minimal complications and promising short-term outcomes. This technique provides a viable alternative for patients contraindicated for oral mucosal grafts, potentially reducing morbidity associated with traditional intestinal mucosa harvesting methods.

Urethro vaginal injuries associated with pelvic fracture - A spectrum of clinical presentation and management

BACKGROUND

Blunt trauma to the paediatric pelvis is associated with urethral rupture, sometimes even without a bony fracture. While such rupture of the male urethra has received considerable mention, female urethral injury is both less common and has received less attention.

OBJECTIVE

We describe 4 cases of urethro vaginal injury associated with pelvic fracture, its varied presentations and the modalities employed in its management.

PATIENTS AND METHODS

A retrospective study was done to identify 4 patients who presented to our institution between 2007 and 2018. All 4 girls suffered a loss of a urethral segment ranging from the distal urethra (n = 2) to complete urethral loss (n = 2) and rupture of the bladder neck in one. All 4 girls also had associated vaginal injury resulting in varied clinical presentation including total urinary incontinence, urocolpos, vaginal voiding via an acquired hypospadias and urinary retention with late onset haematocolpos. All were managed initially with SPC and three of them underwent urethral substitution with Monti ileal tube in two and vestibular mucosal flap in one. The hypospadiac neo-meatus was continent and was left alone. The ruptured vagina was repaired by rectus muscle interposition, direct suturing, posterior vaginal U flap or colonic patch. An appendicular Mitrofanoff was added for safety in 2 girls.

RESULTS

Follow up was done till June 2019 (range 1-12 years). All patients voided satisfactorily and were fully continent. Normal menstrual function was present in the 3 post pubertal children.

CONCLUSION

A traumatic force capable of causing urethral injury may often result in associated vaginal injury and should not be overlooked. Thus urinary retention is not the only presentation of urethral injury in girls. Fistulation to the vagina may result in continent or incontinent vaginal voiding if the vagina has not been transected and urocolpos/haematocolpos in those with vaginal transection. Various modalities maybe employed to maintain continuity of the urethra and vagina including use of bowel and local flaps.

Use of rectal mucosal grafts in substitution urethroplasty: an early series

Background

To evaluate the feasibility of use of rectal mucosal grafts for augmentation urethroplasty.

Methods

A series of five patients who underwent rectal mucosal graft urethroplasty for urethral stricture disease were identified. Descriptive statistics were used to describe these patients. Primary endpoints were recurrence of stricture and perioperative morbidity.

Results

Five patients underwent rectal mucosal graft augmentation urethroplasty. Four had a history of prior buccal mucosal graft (BMG) urethroplasty and one had a history of head and neck cancer. Rectal mucosa was noted to be thinner and required more tailoring than buccal mucosa. All patients had patent urethras at time of postoperative retrograde urethrogram. A small diverticulum was noted in one patient with no further sequelae. No complications from rectal mucosal graft harvest were noted. All patients with prior buccal grafting subjectively preferred the rectal graft due to fewer side effects. Subjectively, patients with prior buccal grafts preferred the post-operative recovery following rectal mucosal graft urethroplasty.

Conclusions

Rectal mucosal graft augmentation urethroplasty is a safe alternative in patients with contraindications to buccal grafting with limited morbidity.

Urethral Reconstruction with Rectal Mucosa Graft Onlay: A Novel, Minimally Invasive Technique

PURPOSE

Alternative grafts are needed for patients who are not suitable candidates for oral mucosa graft harvest or who have a paucity of oral mucosa graft available for reconstruction. Circumferential colonic mucosal grafts have demonstrated feasibility for urethral reconstruction, although sigmoid resection has been required for graft retrieval. We report the feasibility and short-term outcomes of urethral reconstruction using a rectal mucosa graft harvested by a novel, minimally invasive, transanal endoscopic microsurgical technique.

MATERIALS AND METHODS

We retrospectively reviewed the records of all patients who underwent transanal endoscopic microsurgical rectal mucosa graft harvest and onlay urethroplasty since the technique was first implemented in 2013. Graft failure was defined as inability to pass a 16Fr cystoscope in the grafted urethra.

RESULTS

All 4 strictures were bulbopendulous with a median length of 13.5 cm (range 10 to 21). Median followup was 18 months (range 12 to 28). Stricture etiology was lichen sclerosus in 3 patients and failed hypospadias interventions in 1. Three patients had undergone at least 1 prior urethroplasty. In 1 patient stricture recurred in the graft 10 months following reconstruction. There were no colorectal complications.

CONCLUSIONS

To our knowledge this is the first study demonstrating urethral reconstruction using a rectal mucosa graft harvested by the transanal endoscopic microsurgical technique. Initial data revealed that this technique is feasible and safe, and minimizes graft harvest morbidity. Transanal endoscopic microsurgical harvest of a rectal mucosa graft may provide an alternative graft material for patients with long segment urethral strictures who are not candidates for oral mucosa graft harvest. Further experience and longer followup are needed to validate these findings.

The Selection of Procedures in One-stage Urethroplasty for Treatment of Coexisting Urethral Strictures in Anterior and Posterior Urethra

OBJECTIVE

To explore selection of the procedures in one-stage urethroplasty for treatment of coexisting urethral strictures in the anterior and posterior urethra.

METHODS

Between 2008 and 2014, a total of 27 patients with existing strictures simultaneously at anterior urethra and posterior urethra were treated in our hospital. Two types of procedures were selected for treatment of the anterior urethral strictures. A penile skin flap and the lingual mucosa were used for augmented urethroplasty in 20 and 7 cases, respectively. Three types of procedures, namely, non-transecting end-to-end urethral anastomosis (n = 3), traditional end-to-end urethral anastomosis (n = 17), other grafts substitution urethroplasty, including pedicle scrotal skin urethroplasty (n = 2), and lingual mucosal graft urethroplasty (n = 5), were utilized in the treatment of posterior urethral strictures.

RESULTS

The patients were mean followed up 30 months with an overall success rate of 88.9%. The majority of the patients exhibited wide patent urethras on retrograde urethrography and the patients' urinary peak flow ranged from 14.2 to 37.9 ml/s. Complications developed in 3 patients (11.1%). Of the 17 patients who underwent traditional urethral end-to-end anastomosis, urethral strictures occurred in 2 patients at 4 and 6 months after the operation. These patients achieved a satisfactory voiding function after salvage pedicle scrotal skin urethroplasty. A urethral pseudodiverticulum was observed in another patient 9 months after pedicle penile flap urethroplasty; and after a salvage procedure, he regained excellent voiding function.

CONCLUSION

Synchronous anterior and posterior strictures can be successfully reconstructed with a combination of substitution and anastomotic urethroplasty techniques.

Urethral reconstruction using bone marrow mesenchymal stem cell- and smooth muscle cell-seeded bladder acellular matrix

BACKGROUND

Congenital or acquired abnormalities may lead to a urethral defect that often requires surgical reconstruction. The traditional methods often lead to complications, including urethrocutaneous fistulae and strictures. In this study, we proposed to construct a tissue-engineered sheet graft (TESG) using a bone marrow mesenchymal stem cell (BMSC)- and smooth muscle cell (SMC)-seeded bladder acellular matrix (BAM) for urethral reconstruction.

METHODS

Rabbit BMSCs and SMCs were isolated, expanded, and identified in vitro before seeding into BAM as the experimental group, whereas BAM-only was the control group. The graft was used to construct TESG for implantation into the rabbit omentum for 2 weeks before urethral reconstruction. We divided 24 male rabbits into four experimental groups six each, and six other were the control group. Histological analysis was performed at 2 weeks, 4 weeks, 8 weeks, and 16 weeks postoperatively. Retrograde urethrography was performed at 16 weeks postoperatively.

RESULTS

All experimental rabbits survived to they were humanly killed. At 8 weeks, there was no difference between the graft and the normal urethra with no severe shrinkage. At 8 and 16 weeks after TESG grafting in vivo, multilayer urothelium covered the graft, neovascularization was visible within the center of TESG, and organized smooth muscle bundles were present. Retrograde urethrography failed to demonstrate diverticula formation or urethral stricture. Three control rabbits died within 4 weeks postoperatively. Autopsy showed their urethras to be almost completely blocked whereas another three hosts displays urethral strictures.

CONCLUSION

A TESG was constructed using a BMSC- and SMC-seeded BAM for urethral reconstruction.

Tissue-engineered buccal mucosa using silk fibroin matrices for urethral reconstruction in a canine model

BACKGROUND

To investigate the feasibility of urethral reconstruction using tissue-engineered buccal mucosa (TEBM) with silk fibroin (SF) matrices in a canine model.

MATERIALS AND METHODS

Autologous oral keratinocytes and autologous fibroblasts were isolated, expanded, and seeded onto SF matrices to obtain TEBM. The TEBM was assessed using hematoxylin and eosin staining and scanning electron microscopy. A 5-cm urethral mucosal defect was created in 10 female canines. Urethroplasty was performed using TEBM in five canines in the experimental group and with SF matrices without cells in the five canines in the comparison group. Retrograde urethrography was performed after 6 mo of grafting. The urethral grafts were analyzed grossly and histologically.

RESULTS

The oral keratinocytes and fibroblasts exhibited good biocompatibility with the SF matrices. TEBM could be constructed using SF matrices. The canines implanted with the tissue-engineered mucosa voided without difficulty. The retrograde urethrography revealed no sign of stricture. The histologic staining showed that epithelial cells developed gradually and exhibited stratified epithelial layers at 6 mo. In the comparison group, the canines had difficulty voiding, and the retrograde urethrography showed urethra stricture. The histologic staining showed that one to two layers of epithelial cells developed.

CONCLUSIONS

The TEBM using SF matrices could be a potential material for urethra reconstruction.

Traumatic strictures of the posterior urethra in boys with special reference to recurrent strictures

PURPOSE

We report 18 years' experience of traumatic urethral strictures in boys with emphasis on recurrent strictures.

MATERIALS AND METHODS

Thirty-four boys with pelvic fracture urethral strictures underwent 35 repairs: 23 in the primary group (initial suprapubic cystostomy, but no urethral repair) and 12 in the re-do group (previously failed attempt(s) at urethroplasty elsewhere). The median age at operation and stricture length was 8.4 years and 3 cm in the primary and 9 years and 5.4 cm in the re-do group, respectively. Anastomotic urethroplasty was performed wherever possible, or failing this a substitution urethroplasty. Median follow up was 9 years for primary group and 8 years for re-do group.

RESULTS

Primary group: urethroplasty was successful in 22/23, with 10 by perineal and 13 by additional transpubic approach. Two have stress incontinence. Erectile function is unchanged in all and upper tracts are maintained. One had recurrent stricture. Re-do group (12 including 1 recurrence from primary group): anastomotic urethroplasty was done in 5 and substitution urethroplasty in 7. Patients needing substitution had long stricture (>5 cm), stricture extending to distal bulb, or high riding bladder neck. All patients are voiding urethrally. Two patients with substitution required dilatation for early re-stenosis. One appendix substitution required delayed revision. Two have stress incontinence. Erectile function was unaffected. Upper tracts are maintained.

CONCLUSIONS

Anastomotic urethroplasty was successful in over 95% of primary cases. In re-do cases it was viable in only 41% of cases; the rest required substitution urethroplasty. Urethral substitution also gave acceptable results.

Production of an optimized tissue-engineered pig connective tissue for the reconstruction of the urinary tract

Nonurological autologous tissues are used for urethral reconstruction to correct urinary tract disorders but are still leading to complications. Other substitutes have been studied on small animal models without great success. For preclinical tests, we selected the porcine model for its similarity to the human urinary tract. Up to now, porcine skin fibroblasts were not able to synthesize enough extracellular matrix under standard conditions to sustain the formation of an adequate tissue for transplantation purposes. Therefore, our goal was to optimize the harvesting site and culture conditions to obtain a thick and easy to handle porcine fibroblast tissue. The oral mucosa was found to be the ideal harvesting site, and a culture temperature of 39°C enabled the formation of a good porcine fibroblast sheet. We successfully superimpose three fibroblast sheets that merged into a thick and resistant tissue where physiological extracellular matrix was produced. Mechanical resistance evaluation by uniaxial traction on the three-layer fibroblast constructs also demonstrated its suitable properties. The production of this porcine connective tissue offers an interesting option in the field of urological tissue engineering. Autologous experiments on a larger animal model are now possible and accessible, allowing the performance of long-term in vivo studies.

Evaluation of the biocompatibility and mechanical properties of naturally derived and synthetic scaffolds for urethral reconstruction

The aim of this study was to evaluate the mechanical properties and biocompatibility of biomaterials, including bladder submucosa (BAMG), small intestinal submucosa (SIS), acellular corpus spongiosum matrix (ACSM), and polyglycolic acid (PGA), to identify the optimal scaffold for urethral tissue engineering. Tensile mechanical testing was conducted to evaluate mechanical properties of each scaffold. Rabbit corporal smooth muscle cells were cultured with the extracts of biomaterials and mitochondrial metabolic activity assay was used to determine the cytotoxicity of scaffold. The pore sizes of each scaffold were measured. Additionally, smooth muscle cells were seeded on biomaterials. Cell infiltration was evaluated. Mechanical evaluation showed that Young modulus, stress at break in ACSM were prior to those in other biomaterials (p < 0.05). MTT assay confirmed that all scaffolds supported normal cellular mitochondrial metabolic without inducing cytotoxic events. SEM demonstrated that PGA has the largest pore size (>200 microm). The ACSM has different pore sizes in urethral (<5 microm) and cavernosal surfaces (>10 microm). Widespread distribution of cells could be observed in PGA 14 days after seeding. Multilayer cellular coverage developed in BAMG and urethral surface of ACSM without any sign of cellular invasion. Moderated cellular penetration could be found in SIS and cavernosal surface of ACSM. Although each scaffold demonstrated suitable mechanical properties, which is similar to normal urethra, ACSM showed better response in some parameters than those in other biomaterials. It suggested that this scaffold may be an alternative for urethral reconstruction in the future. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res, 2010.

Entero-urethroplasty for the salvage of bulbo-membranous stricture disease or trauma

OBJECTIVE

To describe a salvage procedure for bulbo-membranous stricture disease or trauma.

PATIENTS AND METHODS

Over a 10-year period 11 patients with otherwise unsalvageable strictures of the bulbo-membranous urethra or defects after trauma were treated by interposition of a tailored intestinal flap. An intestinal flap, on average 8 cm in length, was harvested from the ileum, the stomach, the right colon or (preferably) the sigmoid colon, and tailored to a calibre of 26-30 F. It was then sutured between the stump of the prostate and the distal bulbar or proximal pendulous urethra either following the normal perineal route for the urethra or a more direct route through a trench cut in the superior pubic ramus.

RESULTS

Three patients developed proximal anastomotic contractures requiring interval dilatation in one and revision in two. Two patients developed a stone in the gut segment one of which was removed traumatically causing irreparable damage to the neourethra. The results were otherwise satisfactory.

CONCLUSION

For an otherwise unsalvageable bulbo-membranous stricture or defect, a tailored flap of intestine, preferably sigmoid colon, gives satisfactory results. Of the two potential routes for the neourethra, we have more experience with the normal route but the direct route has several advantages.

Urethral substitution with ileum in traumatic bladder neck-vagina fistula

A five-year-old girl presented with post traumatic urinary incontinence secondary to rupture of the bladder neck into the vagina. Operative repair included a midline exposure with resection of the symphysis pubis, separation of the bladder neck from the vagina, repair of the torn bladder neck and urethral substitution with ileum. Normal continence and voiding was achieved.

Urethral substitution using autologous lingual mucosal grafts: an experimental study

OBJECTIVE

To investigate the feasibility of urethral substitution using free lingual mucosa grafts (LMGs) in a dog model.

MATERIALS AND METHODS

The study included 10 female mongrel dogs in which a 4 x 1 cm(2) section of urethral mucosa was excised. The defect was immediately repaired with a size-matched free LMG harvested from the inferior lateral surface of the tongue. A 12 F urethral catheter was kept inside the urethra for a mean of 7 days. At 3 months after the procedure, the patency of the urethra was assessed by both insertion of a 12 F catheter and by retrograde urethrography. Dogs were killed, the grafted areas excised, and evaluated by gross and histopathological examination.

RESULTS

All dogs survived the procedure and there were no tongue complications. One of the 10 dogs developed a slight urethral stricture near the proximal anastomosis. The remaining nine dogs voided spontaneously with no difficulty. Retrograde urethrography showed that no strictures or fistulas had formed. The LMGs shortened by 9.5% after surgery, from a mean (sd) of 4 (0.13) to 3.62 (0.11) cm (statistically significant, P < 0.05). Histological examination showed that the LMGs were well-incorporated into the urethral walls and covered by a keratinized squamous epithelium. Neovascularization was evident beneath the grafts.

CONCLUSION

We successfully developed an dog model for free LMGs and showed the feasibility of this approach for urethral substitution.

Urethral reconstruction using autologous and everted vein graft: an experimental study

Urethral reconstruction is one of the problematic issues in pediatric surgery. To evaluate the efficacy of vein graft for urethral reconstruction in rabbits, about 3 cm of distal urethra was excised under microscopic magnification. In groups A, B, and D, the urethra was replaced with the internal jugular vein. In group B, before performing anastomosis, vein grafts were everted. In group C (control group) after removing the urethra, a catheter was inserted without substituting the urethra and then fixed. Groups A, B, and C were kept for 3 months. Group D was divided into five subgroups each consists of two rabbits, which were killed at days 7, 10, 14, 22, and 30 for evolutionary histopathological studies. Gross evaluation, retrograde urethrography, and histopathological studies were also performed in other groups. Retrograde urethrography and gross evaluation revealed no sign of stricture and fistula formation in six and eight rabbits in groups A and B, respectively. However, those complications were observed in all the rabbits in group C. The grafted part of the neourethra was epithelialized with uroepithelium in all rabbits in group A (vein graft) and group B (everted vein graft) but only partial epithelialization was observed in three rabbits of group C. Severe fibrosis with stricture formation was developed in six rabbits in the control group. In group D, epithelialization gradually replaced necrosis and inflammation, within 1 month. This study showed that vein, everted or not, can be used as a substitute for urethra. It also suggests that new epithelialization might be formed from ingrowing of the uroepithelium from the proximal part.