Harnleiterrekonstruktion mit rekonfigurierten Ileumsegmenten nach Yang-Monti: Prospektiver 4-Jahres-Bericht

Bioengineering solutions for Ureteric disorders: Clinical need, challenges and opportunities

Objectives

To summarise the causes of ureteric damage and the current standard of care, discussing the risks and benefits of available therapeutic options. We then focus on the current and future solutions that can be provided by ureteric bioengineering and provide a description of the ideal characteristics of a bioengineered product.

Methods

We performed a literature search in February 2021 in: Google Scholar, Medline, and Web of Science. Three searches were conducted, investigating: (a) the epidemiology of ureteric pathology, (b) the current standard of care, and (c) the state of the art in ureteric bioengineering.

Results

The most‐common causes of ureteric damage are iatrogenic injury and external trauma. Current approaches to treatment include stent placement or surgical reconstruction. Reconstruction can be done using either urological tissue or segments of the gastrointestinal tract. Limitations include scarring, strictures, and infections. Several bioengineered alternatives have been explored in animal studies, with variations in the choice of scaffold material, cellular seeding populations, and pre‐implantation processing. Natural grafts and hybrid material appear to be associated with superior outcomes. Furthermore, seeding of the scaffold material with stem cells or differentiated urothelial cells allows for better function compared to acellular scaffolds. Some studies have attempted to pre‐implant the graft in the omentum prior to reconstruction, but this has yet to prove any definitive benefits.

Conclusion

There is an unmet clinical need for safer and more effective treatment for ureteric injuries. Urological bioengineering is a promising solution in preclinical studies. However, substantial scientific, logistic, and economic challenges must be addressed to harness its transformative potential in improving outcomes.

Adult iatrogenic ureteral injury and stricture-incidence and treatment strategies

Iatrogenic ureteral injuries and strictures are relatively common complication of pelvic surgery and radiation treatment. Left untreated they are associated with severe short- and long-term complications such as urinoma, septic state, renal failure, and loss of a renal unit. Treatment depends on timing of diagnosis, as well as extent of injury, and ranges from simple endoscopic management to complex surgical reconstruction under usage of pedicled grafts. While recent advances in ureteral tissue engineering are promising the topic is still underreported. Historically a domain of open surgery, laparoscopic and robotic-assisted approaches have proven their feasibility in small case series, and are increasingly being utilized as means of reconstructive surgery. This review aims to give an outline of incidence and treatment of ureteral injuries and strictures in light of the latest advances.

Long-term results of ileal ureteric replacement: a 25-year single-centre experience

OBJECTIVE

To report the long-term outcomes of ileal ureteric replacement (IUR) in complex reconstruction of the urinary tract.

PATIENTS AND METHODS

From 1991 to 2016, IUR was performed in 157 patients with structural or functional ureteric loss. In 52 patients, bilateral IUR became necessary. Implantation sites where either the native urinary bladder (n = 79) or intestinal reservoirs (n = 78). In the latter group, the technique was used at the time of primary urinary diversion (n = 34), in a secondary approach (n = 29), and in undiversion or conversion procedures (n = 15). Anti-refluxive implantation was performed in 37 patients. In eight patients the ileal ureter was implanted into the cutis as an ileal conduit. All patients were followed prospectively according to a standardised protocol.

RESULTS

The mean follow-up was 54.1 months. In 114 patients with dilatation of the upper urinary tract before surgery a significant improvement of the dilatation was confirmed in 98 patients. Serum creatinine levels decreased or remained stable in 147 of the 157 patients. Reflux was present in all cases without and in six cases with an anti-reflux mechanism. In six patients, operative revision became necessary because of severe metabolic acidosis, mucus obstruction or stenosis of the ileal ureter.

CONCLUSIONS

To our knowledge, this is the world's largest single-centre series of IUR reported to date. Long-term follow-up confirms that this approach is a safe and reliable solution, even under complex conditions. Anti-refluxive implantation is recommended for intestinal reservoirs, whereas reflux prevention seems to be of minor importance when the native bladder is chosen as the site of implantation.

[Ureteral stricture as a late complication of radiotherapy : Possible treatment options]

Ureteral strictures are uncommon complications of radiotherapy which are often recognized late. Their consequences range from harmless dilatation of the ureter to loss of renal function and potential life-threatening urosepsis.Therapy of radiogenic ureteral stricture is a challenging task for every urologist. Several surgical strategies including minimally invasive procedures, reconstruction and partial or complete replacement of the ureter are available.This article provides an overview of the various options in the treatment of radiogenic stricture of the ureter, focusing on the use of ileum and colon segments for ureteral substitution.

[Avoidance and management of complications in open surgical ureter reconstruction]

Open surgical reconstruction of the ureter is a urological procedure with a potentially high risk of complications. The correct selection of patients and time of operation are important aspects regarding the treatment strategy. Position and length of the affected ureter segment to be reconstructed determine the surgical intervention possibilities. The psoas hitch procedure is a well-established technique for distal reconstruction of the ureter where most iatrogenic injuries occur. In more proximal or complex defects, several procedures are available. Partial or complete replacement of the ureter with bowel is still considered the standard for bridging long ureteral defects but is accompanied with higher intra- and postoperative complication rates. In specific patients and situations, autotransplantation of the kidney and subcutaneous pyelovesical bypasses are clinical options. Using mucosal grafts or tissue engineering may be new therapeutic prospects to cover ureteral defects but the clinical impact still needs to be clarified. All therapeutic strategies share the fact that great surgical expertise and experience are necessary as the operative technique must be mastered to avoid severe complications.

Strategies for open reconstruction of upper ureteral strictures

This article presents a review of the literature regarding surgical techniques and outcomes for reconstruction of strictures involving the upper ureter. The preoperative assessment for proximal ureteral stricture is briefly reviewed, followed by a discussion of ureteroureterostomy, transureteroureterostomy, ureterocalicostomy, bladder flaps, downward nephropexy, bowel interposition grafts, onlay or tubular grafting, renal autotransplantation, and nephrectomy. The future direction for reconstruction of the proximal ureter is proposed.

Management of a hypoplastic lower urinary tract: a case report

This case relates to a child with an antenatal diagnosis of severe bilateral hydronephrosis with congenital anomalies of the ureters, bladder, and urethra. We describe the presentation and surgical management, highlighting the complexity of this anomaly and the surgical technique used to reconstruct the lower urinary tract. To our knowledge, there has not been a similar case in the literature and the use of a segment of colon for ureteric substitution in children has not been previously reported in the literature.

[Ureteral reconstruction after ureterorenoscopic injuries]

Ureteral injuries are caused by iatrogenic reasons in about 75% of cases. Among urological procedures ureterorenoscopy (URS) is mainly described as the reason for ureteral injury, although complication rates of URS are generally low. Injuries of the ureter are divided into five grades by the AAST. Grades I-II are referred to as partial and grades III-V as complex ureteral injuries. To avoid higher complication rates there should be no delay in confirmation of diagnosis and initiation of therapy. Correct therapy depends on grade of injury. Partial ureteral injuries are treated by endoscopic inlay of a ureteral stent for approximately 14-21 days. In complex injuries endoscopic ureteroureterostomy could be attempted but leads to rather poor long-term results depending on the length of devascularization of the injured ureter.Procedures with and without use of bowel for ureteral reconstruction and replacement have been described. The type of operative procedure should be selected based on location and degree of ureteral injury. Besides ureteral reconstruction, autotransplantation of the affected kidney can be required in individual cases.