Onlay Repair Technique for the Management of Ureteral Strictures: A Comprehensive Review

Newly modified 'pseudo flap' without compromising vascularity to enhance repair of long distal ureteral loss: A retrospective analysis of a prospective database

Objective

To present an alternative technique called pseudo-flap for reconstructing long ureteral defects as an alternative to Boari flap. Despite being used for more than 70 years by urologists for tension-free reconstruction of distal and mid-ureteral defects, the Boari flap exhibits high complication rates, with an average of 27% (range 5.5%-30.4%). These complications arise from compromised blood supply, attributed to incisions made on all three sides of the flap and dependence on the flap base as the sole source of blood supply.

Methods

We retrospectively reviewed patients who underwent our modified technique by a single surgeon between 2008 and 2021. We used a semi-oblique cystotomy on the lowest part of the anterior and contralateral aspects of the bladder after complete release from adhesions and sacrificing the superior vesical pedicle, if necessary. The innovative part of the technique involved making short relaxing incisions at different levels on both sides of a pseudo-flap while pushing the bladder dome upward to reach the healthy ureter in a tension-free manner, followed by anastomosis with a non-refluxing or refluxing technique.

Results

Fifteen patients underwent the pseudo-flap technique with a mean follow-up of 16.9 months. Four had prior radiation, three had hyperthermic intraperitoneal chemotherapy (HIPEC) for peritoneal carcinomatosis, and one had a ureteral stricture in a transplanted kidney. Eight procedures were performed during intraoperative consultations.Only one patient (7%) developed a major complication (Clavien-Dindo grade ≥2). This patient developed postoperative leak, and none developed obstructive hydronephrosis, suggesting stricture or flap ischemia. The mean length of the flap was 9.3 cm.

Conclusion

Our pseudo-flap technique has lower complication rates than the traditional Boari flap. It is not technically challenging, minimally compromises blood supply and is thus especially suitable for complex, highly morbid patients with decreased tissue vascularity, such as those with prior radiation and peritoneal carcinomatosis.

Recent trends and perspectives in reconstruction and regeneration of intra/extra-oral wounds using tissue-engineered oral mucosa equivalents

Many conditions, including cancer, trauma, and congenital anomalies, can damage the oral mucosa. Multiple cultures of oral mucosal cells have been used for biocompatibility tests and oral biology studies. In recent decades, the clinical translation of tissue-engineered products has progressed significantly in developing tangible therapies and inspiring advancements in medical science. However, the reconstruction of an intraoral mucosa defect remains a significant challenge. Despite the drawbacks of donor-site morbidity and limited tissue supply, the use of autologous oral mucosa remains the gold standard for oral mucosa reconstruction and repair. Tissue engineering offers a promising solution for repairing and reconstructing oral mucosa tissues. Cell- and scaffold-based tissue engineering approaches have been employed to treat various soft tissue defects, suggesting the potential clinical use of tissue-engineered oral mucosa (TEOMs). In this review, we first cover the recent trends in the reconstruction and regeneration of extra-/intra-oral wounds using TEOMs. Next, we describe the current status and challenges of TEOMs. Finally, future strategic approaches and potential technologies to support the advancement of TEOMs for clinical use are discussed.

Laparoscopic ventral onlay ureteroplasty with buccal mucosa graft for complex proximal ureteral stricture

INTRODUCTION

There is lack of papers dedicated to the laparoscopic buccal mucosa graft (BMG) ureteroplasty of the complex upper ureteral stricture. The aim of this study is to evaluate the results of laparoscopic BMG ureteroplasty in patients with complex proximal ureteral stricture.

MATERIAL AND METHODS

Twenty-four patients underwent laparoscopic ventral onlay BMG ureteroplasty for long or recurrent proximal ureteral stricture not amenable to uretero-ureteral anastomosis over 2019-2022. Patient demographics, operative time, estimated blood loss, length of stay, follow-up, intra- and postoperative complication rate and percentage of stricture-free at last visit were analyzed.

RESULTS

The mean stricture length was 3.6 cm. The mean operative time was 208.3 min, while mean blood loss was 75.8 mL. The length of hospital stay was 7.3 days. No intraoperative complications were observed. Postoperatively, seven patients developed complications (29.2%). Five patients experienced a Grade II (according to Clavien nomenclature). Two patients developed a Grade IIIa complication, which included leakage of the anastomosis site. The mean follow-up was on the 22 months with stricture free rate 87.5%.

CONCLUSION

Patients with proximal ureteral strictures could be effectively treated by laparoscopic ventral onlay ureteroplasty with a buccal mucosa graft.

Dorsal oral mucosa graft urethroplasty for female urethral stricture reconstruction: A narrative review

Female urethral stricture is currently a challenging situation. In general, urethra dilatation can be selected for treatment, but the complications and high recurrence rate urge doctors to consider other treatments. Recently, dorsal oral mucosa graft urethroplasty is concerned by more and more surgeons, but there are not enough reports so far. A comprehensive search of dorsal oral mucosa graft urethroplasty was performed. According to the existing literature, there are applications of buccal mucosa and lingual mucosa, and compared with other kinds of grafts, the success rate is higher. However, there is a lack of multicenter, large sample and long follow-up studies. And there is still no enough comparative study between different types of oral mucosa. In summary, dorsal oral mucosa graft urethroplasty is an effective option for the management of female urethral stricture. More multicenter and large sample studies with long-term follow-up data are needed.

Analysis of the efficacy and risk factors of surgical treatment of recurrent UPJO in adults

BACKGROUND

To compare the efficacy of secondary pyeloplasty and balloon dilation and to analyze the risk factors for secondary surgical failure in patients with recurrent uretero-pelvic junction obstruction (UPJO).

METHODS

We retrospectively analyzed 65 patients with recurrent UPJO who underwent secondary surgery between September 2011 and March 2019, of whom 33 had complete baseline data and follow-up data. General clinical information, perioperative data, and follow-up results were collected from patients. Risk factors for surgical failure in patients with recurrent UPJO were analyzed using logistic regression.

RESULTS

The failure rates of secondary pyeloplasty and balloon dilation in secondary surgery were 16.7% and 33.3%, respectively. Univariate analysis showed that ureteral stenosis length and operative time were associated with secondary pyeloplasty and balloon dilatation failure (p < 0.05), and ureteral stenosis length was an independent risk factor for secondary pyeloplasty failure (OR = 0.074, 95% CI: 0.006-0.864, p = 0.038). In the balloon dilation group, treatment failure rates were significantly lower in patients with stenotic segment lengths less than 1 ± 0.32 cm than in patients with stenotic segment lengths greater than 1 ± 0.32 cm (p = 0.019).

CONCLUSIONS

The secondary pyeloplasty may provide better benefit. Ureteral stricture length is an independent risk factor for failure of secondary pyeloplasty and a potential risk factor for balloon dilatation. Operation time is a potential risk factor for pyeloplasty and balloon dilatation.

Application of antibody-conjugated small intestine submucosa to capture urine-derived stem cells for bladder repair in a rabbit model

The need for bladder reconstruction and side effects of cystoplasty have spawned the demand for the development of alternative material substitutes. Biomaterials such as submucosa of small intestine (SIS) have been widely used as patches for bladder repair, but the outcomes are not fully satisfactory. To capture stem cells in situ has been considered as a promising strategy to speed up the process of re-cellularization and functionalization. In this study, we have developed an anti-CD29 antibody-conjugated SIS scaffold (AC-SIS) which is capable of specifically capturing urine-derived stem cells (USCs) in situ for tissue repair and regeneration. The scaffold has exhibited effective capture capacity and sound biocompatibility. In vivo experiment proved that the AC-SIS scaffold could promote rapid endothelium healing and smooth muscle regeneration. The endogenous stem cell capturing scaffolds has thereby provided a new revenue for developing effective and safer bladder patches.

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We developed an anti-CD29 antibody-crosslinked submucosa of small intestine scaffold (AC-SIS).

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AC-SIS is capable of specifically capturing urine-derived stem cells (USCs) as well as possesses a sound biocompatibility.

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AC-SIS promotes in situ tissue regeneration by facilitating the repair of bladder epithelium, smooth muscle and angiogenesis.

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Design and application of endogenous stem cell capturing scaffolds provides a new strategy for bladder repair.

Autologous Bilayered Adipose-Derived Mesenchymal Cell-Gelatin Sheets Reconstruct Ureters in Rabbits

Repair of ureteral defects or strictures due to disease or trauma is usually dependent upon surgery that often requires either reoperation or an alternative treatment. By taking advantage of tissue engineering and regenerative techniques, it may be possible to define new approaches to ureteral repair. In this study, we fabricated autologous bilayered adipose-derived mesenchymal cell (AMC)-gelatin sheets and transplanted them into rabbits to replace surgically excised ureteral segments. AMCs harvested from abdominal adipose tissues of female New Zealand White rabbits were cultured on collagen-coated dishes and labeled with PKH26, a red fluorescent dye, for later identification. Monolayers of the cultured PKH26-labeled AMCs were detached and applied to gelatin hydrogel sheets. Two gelatin sheets were then united with the AMC monolayers apposed together, forming a bilayered AMC-gelatin sheet. Following each partial ureterectomy, a bilayered autologous AMC-gelatin sheet was transplanted, joining the proximal and distal ends of the remaining the ureter (n=9). Control animals underwent the same procedure except that the transplant was achieved with a bilayered acellular-gelatin sheet (n=9). At 4 and 8 weeks after transplantation, the proximal regions of ureters treated with the control bilayered acellular-gelatin sheets exhibited flexures and dilations, which are not characteristic of unoperated ureters. In contrast, the bilayered AMC-gelatin sheet transplanted rabbits did not have ureteral flexures or dilations. About midway between the proximal and distal ends, both the control and experimental reconstructed ureteral walls had smooth muscle layers; however, those in the experimental reconstructed ureteral walls were significantly thicker and better organized than those in the control reconstructed ureteral walls. Some AMCs differentiated into smooth muscle marker-positive cells. The experimental ureteral walls contained smooth muscle cells derived from the PKH26-labeled AMCs and others that were derived through migration and differentiation of cells from the remaining proximal and distal ends of the original ureter. In addition, the lumina of the 8-week reconstructed ureteral tissues in experimental rabbits did not show histological strictures as seen in the control ureters. These results suggest that the bilayered AMC-gelatin sheets have the potential to replace defective tissues and/or reconstruct damaged ureters.

Modified robotic-assisted laparoscopic pyeloplasty in children for ureteropelvic junction obstruction with long proximal ureteral stricture: The "double-flap" technique

OBJECTIVE

The objective of this study is to introduce a novel technique of robotic-assisted laparoscopic pyeloplasty (RALP) for ureteropelvic junction obstruction (UPJO) with long proximal ureteral stricture in children.

MATERIALS AND METHODS

Clinical information on patients who underwent a modified RALP between July 2018 and May 2019 in our center was collected retrospectively. Our surgical modifications mainly include "double-flap" tailoring of the renal pelvis and anastomosis of spatulate ureter with the double-flap. Demographic, perioperative, postoperative, and follow-up information was recorded in detail.

RESULTS

A total of 13 patients were included in the study. All the patients underwent a modified RALP without conversion to open surgery. They were followed up with a median time of 36 months. The anteroposterior diameter of the renal pelvis was 1.19 ± 0.21 at 6 months after the surgery, which was significantly lower than that on admission (3.93 ± 0.79). The split renal function of the children was also significantly improved from 0.37 ± 0.05) to 0.46 ± 0.02 at 6 months after surgery (p < 0.05). The diuretic renography revealed that all the patients have a T1/2 time less than 20 min postoperatively. The children were in good condition during the follow-up period.

CONCLUSIONS

Modified RALP is an effective surgical treatment for children with UPJO with long proximal ureteral stricture. The success rate of this modification has been preliminarily confirmed.

Tissue engineering in reconstructive urology-The current status and critical insights to set future directions-critical review

Advanced techniques of reconstructive urology are gradually reaching their limits in terms of their ability to restore urinary tract function and patients' quality of life. A tissue engineering-based approach to urinary tract reconstruction, utilizing cells and biomaterials, offers an opportunity to overcome current limitations. Although tissue engineering studies have been heralding the imminent introduction of this method into clinics for over a decade, tissue engineering is only marginally applied. In this review, we discuss the role of tissue engineering in reconstructive urology and try to answer the question of why such a promising technology has not proven its clinical usability so far.

Comment on renal autotransplantation: A final option to preserve the kidney after an iatrogenic ureteral injury

To the Editor, Autologous Renal Transplantation (ART) since firstly described in 1963 by Hardy, has been used in various cases. There are various reasons for the transplantation such as iatrogenic ureteral damage, chronic kidney pain, unresectable renal tumors or renovascular diseases. Indications concerning the suitable patients for this kind of procedure are gradually increasing. Nevertheless, each case is unique, and the treatment must be personalized [...].

Validation of robotic-assisted ureteroplasty with buccal mucosa graft for stricture at the proximal and middle ureters: the first comparative study

Although ureteroplasty with buccal mucosa graft for long-segmental ureteral stenosis has been developed long ago, evidence was still restricted to case series in published literature. This study aims to validate ureteroplasty with buccal mucosa graft (BMG) in long-segment stricture at the proximal and middle ureters under designed comparative methods. From April 2015 to January 2019, we performed robotic-assisted ureteroplasty with BMG with a two-phase design and compared ureteroplasty and BMG (phase 2 surgery) with endoscopic stenting (phase 1 surgery). Paired data of effective renal plasma flow (ERPF), glomerular filtration rate (GFR), hydronephrosis grade, and physical and psychological domains of the World Health Organization Quality of Life (WHOQOL)-BREF were compared. A total of 29 patients were enrolled, and only three (10%) patients had hydronephrosis resolution after treatment with endoscopic stenting (p = 0.250 to baseline). Compared to endoscopic ureteral stent, Hedges' g of ureteroplasty with BMG was 0.56 (95% CI 0.43-0.69), 0.63 (95% CI 0.46-0.80), 0.80 (95% CI 0.56-1.04), and 1.06 (95% CI 0.69-1.43) in EGFR, GFR, physical domain of WHOQOL-BREF, and psychological domain of WHOQOL-BREF, respectively (All significance; p < 0.001). After 12-month follow-ups, no recurrence of stricture was reported. In conclusion, Robotic-assisted ureteroplasty with BMG onlay is efficient in reconstruction of long-segment stricture of the proximal and middle ureters.

Evaluation of Bi-Layer Silk Fibroin Grafts for Tubular Ureteroplasty in a Porcine Defect Model

Ureteral reconstruction with autologous tissue grafts is often limited by tissue availability and donor site morbidity. This study investigates the performance of acellular, bi-layer silk fibroin (BLSF) scaffolds in a porcine model of ureteroplasty. Tubular ureteroplasty with BLSF grafts in combination with transient stenting for 8 weeks was performed in adult female, Yucatan, mini-swine (N = 5). Animals were maintained for 12 weeks post-op with imaging of neoconduits using ultrasonography and retrograde ureteropyelography carried out at 2 and 4 weeks intervals. End-point analyses of ureteral neotissues and unoperated controls included histological, immunohistochemical (IHC), histomorphometric evaluations as well as ex vivo functional assessments of contraction/relaxation. All animals survived until scheduled euthanasia and displayed mild hydronephrosis (Grades 1-2) in reconstructed collecting systems during the 8 weeks stenting period with one animal presenting with a persistent subcutaneous fistula at 2 weeks post-op. By 12 weeks of scaffold implantation, unstented neoconduits led to severe hydronephrosis (Grade 4) and stricture formation in the interior of graft sites in 80% of swine. Bulk scaffold extrusion into the distal ureter was also apparent in 60% of swine contributing to ureteral obstruction. However, histological and IHC analyses revealed the formation of innervated, vascularized neotissues with a-smooth muscle actin+ and SM22α+ smooth muscle bundles as well as uroplakin 3A+ and pan-cytokeratin + urothelium. Ex vivo contractility and relaxation responses of neotissues were similar to unoperated control segments. BLSF biomaterials represent emerging platforms for tubular ureteroplasty, however further optimization is needed to improve in vivo degradation kinetics and mitigate stricture formation.

The Expanding Use of Buccal Mucosal Grafts in Urologic Surgery

The advent and success of buccal mucosal grafts as a substitution material in the urinary tract has changed the landscape of reconstructive urology. Due to its ease to harvest, low morbidity, and advantageous properties, there has been a growing number of applications for buccal mucosal grafts in upper and lower urinary tract reconstruction as well as genital reconstruction. In this article, we review the historical application and the evolution of buccal mucosal grafts and provide an up-to-date review on its utilization in urologic procedures.

Lyophilized Polyvinylpyrrolidone Hydrogel for Culture of Human Oral Mucosa Stem Cells

This work shows the synthesis of a polyvinylpyrrolidone (PVP) hydrogel by heat-activated polymerization and explores the production of hydrogels with an open porous network by lyophilisation to allow the three-dimensional culture of human oral mucosa stem cells (hOMSCs). The swollen hydrogel showed a storage modulus similar to oral mucosa and elastic solid rheological behaviour without sol transition. A comprehensive characterization of porosity by scanning electron microscopy, mercury intrusion porosimetry and nano-computed tomography (with spatial resolution below 1 μm) showed that lyophilisation resulted in the heterogeneous incorporation of closed oval-like pores in the hydrogel with broad size distribution (5 to 180 μm, d₅₀ = 65 μm). Human oral mucosa biopsies were used to isolate hOMSCs, expressing typical markers of mesenchymal stem cells in more than 95% of the cell population. Direct contact cytotoxicity assay demonstrated that PVP hydrogel have no negative effect on cell metabolic activity, allowing the culture of hOMSCs with normal fusiform morphology. Pore connectivity should be improved in future to allow cell growth in the bulk of the PVP hydrogel.

Buccal ureteroplasty for recurrent extended strictures and obliterations of distal ureter

At the current stage of development of urology, selection of the surgical method for cases of severe obstructive diseases of the upper urinary system remains a challenge. This study aimed to explore the results of application of a buccal graft (BG) to remedy extended recurrent strictures and obliterations of the distal ureter. Seven patients with the mentioned diseases had undergone surgery: for six of them, the method of choice was complete BG ureteroplasty, one had onlay ureteroplasty. One intervention was laparoscopic, the remaining surgeries were open. The length of the replaced ureteral defect was 5–8 cm. In five cases, the flap was additionally vascularized with the iliac muscle, in one we used omentum tissue, in another — both the iliac muscle and the omentum. There were no fatalities registered, nor severe complications as per the Clavien–Dindo classification. The patients were followed-up for 4–18 months; as of today, no recurrence cases were identified. Control examinations showed complete patency of the neoureter and good vascularization of the BG. Thus, this method can be an option in cases disallowing distal ureter restoration with tissues of the patient's own urinary tract or segments of the gastrointestinal tract.