[Update on ureteral reconstruction 2024]

Ureteral strictures can occur along the entire course of the ureter and have many different causes. Factors involved in the development include, among other things, congenital anomalies, iatrogenic injuries during endoscopic as well as open or minimally invasive visceral surgical, gynecological, and urological procedures as well as prior radiation therapy. Planning treatment for ureteral strictures requires a detailed assessment of stricture and patient characteristics. Given the various options for ureteral reconstruction, various methods must be considered for each patient. Short-segment proximal strictures and strictures at the pyeloureteral junction are typically surgically managed with Anderson-Hynes pyeloplasty. End-to-end anastomosis can be performed for short-segment proximal and middle ureteral strictures. Distal strictures are treated with ureteroneocystostomy and are often combined with a Boari and/or Psoas Hitch flap. Particularly, the treatment of long-segment strictures in the proximal and middle ureter remain a surgical challenge. The use of bowel interposition is an established treatment option for this, offering good functional results but also potential associated complications. Robot-assisted surgery is increasingly becoming a minimally invasive treatment alternative to reduce hospital stays and optimize postoperative recovery. However, open surgical ureteral reconstruction remains an established procedure, especially after multiple previous abdominal operations.

Preoperative stricture length measurement does not predict postoperative outcomes in robotic ureteral reconstructive surgery

PURPOSE

We sought to determine whether preoperative stricture length measurement affected the choice of procedure performed, its correlation to intraoperative stricture length, and postoperative outcomes.

METHODS

The Collaborative of Reconstructive Robotic Ureteral Surgery (CORRUS) database was queried for patients undergoing robotic ureteral reconstructive surgery from 2013 to 2021 who had surgical stricture length measurement. From this cohort, we identified patients with and without preoperative stricture length measurement via retrograde pyelogram or antegrade nephrostogram. Outcomes evaluated included intraoperative complications, 30-day complications greater than Clavien-Dindo grade II, hardware-free status, and need for additional procedures.

RESULTS

Of 153 patients with surgical stricture length measurements, 102 (66.7%) had preoperative radiographic measurement. No repair type was more likely to have preoperative measurement. The Pearson correlation coefficient between surgical and radiographic stricture length measurements was + 0.79. The average surgical measurement was 0.71 cm (± 1.52) longer than radiographic assessment. Those with preoperative imaging waited on average 5.0 months longer for surgery, but this finding was not statistically significant (p = 0.18). There was no statistically significant difference in intraoperative complications, 30-day complication rates, hardware-free status at last follow-up, or need for additional procedures between patients with and without preoperative measurement. The only significant predictive factor was preoperative stricture length on 30-day postoperative complications.

CONCLUSIONS

Despite relatively high prevalence of preoperative radiographic stricture length measurement, there are few measures where it offers clinically meaningful diagnostic information towards the definitive surgical management of ureteral stricture disease.

Unveiling the Challenges in Tandem Ureteral Stent Management for Malignant Ureteral Obstruction: Failure Rate, Risk Factors, and Durability of Their Replacement

BACKGROUND

Malignant ureteral obstruction (MUO) is a sequela of advanced malignant disease that requires renal drainage, with tandem ureteral stents (TUSs) being a viable option. This study aimed to evaluate the TUS failure rate, associated risk factors, and the feasibility of replacing failed TUSs with a new pair of stents.

METHODS

A retrospective analysis of MUO patients treated with TUS insertion from 2014 to 2022 was conducted. TUS failure was defined as urosepsis, recurrent urinary tract infections, acute kidney failure, or new hydronephrosis on imaging. Cox proportional hazard regression analysis identified the independent predictors of TUS failure.

RESULTS

A total of 240 procedures were performed on 186 patients, with TUS drainage failing in 67 patients (36%). The median time to failure was 7 months. Multivariate analysis revealed female gender (OR = 3.46, p = 0.002), pelvic mass (OR = 1.75, p = 0.001), and distal ureteral obstruction (OR = 2.27, p = 0.04) as significant risk factors for TUS failure. Of the failure group, 42 patients (22.6%) underwent TUS replacement for a new pair. Yet, 24 (57.2%) experienced a second failure, with a median time of 4.5 months. The risk factors for TUS second failure included a stricture longer than 30 mm (OR = 11.8, p = 0.04), replacement with TUSs of the same diameter (OR = 43, p = 0.003), and initial TUS failure within 6 months (OR = 19.2, p = 0.006).

CONCLUSIONS

TUS insertion for the treatment of MUO is feasible and has good outcomes with a relatively low failure rate. Primary pelvic mass and distal ureteral obstruction pose higher risks for TUS failure. Replacing failed TUSs with a new pair has a success rate of 42.8%. Consideration should be given to placing larger diameter stents when replacing failed TUS.

Complications after Nephron-sparing Interventions for Renal Tumors: Imaging Findings and Management

The two primary nephron-sparing interventions for treating renal masses such as renal cell carcinoma are surgical partial nephrectomy (PN) and image-guided percutaneous thermal ablation. Nephron-sparing surgery, such as PN, has been the standard of care for treating many localized renal masses. Although uncommon, complications resulting from PN can range from asymptomatic and mild to symptomatic and life-threatening. These complications include vascular injuries such as hematoma, pseudoaneurysm, arteriovenous fistula, and/or renal ischemia; injury to the collecting system causing urinary leak; infection; and tumor recurrence. The incidence of complications after any nephron-sparing surgery depends on many factors, such as the proximity of the tumor to blood vessels or the collecting system, the skill or experience of the surgeon, and patient-specific factors. More recently, image-guided percutaneous renal ablation has emerged as a safe and effective treatment option for small renal tumors, with comparable oncologic outcomes to those of PN and a low incidence of major complications. Radiologists must be familiar with the imaging findings encountered after these surgical and image-guided procedures, especially those indicative of complications. The authors review cross-sectional imaging characteristics of complications after PN and image-guided thermal ablation of kidney tumors and highlight the respective management strategies, ranging from clinical observation to interventions such as angioembolization or repeat surgery. Work of the U.S. Government published under an exclusive license with the RSNA. Online supplemental material and the slide presentation from the RSNA Annual Meeting are available for this article. Quiz questions for this article are available in the Online Learning Center. See the invited commentary by Chung and Raman in this issue.

The "Cut-to-the-Light" Technique Laser Endoureterotomy for Complete Ureteral Obstruction Resurfaces! A New Application of an Old Technique

Objective

To describe our new endoscopic approach in treating iatrogenic ureteral stenosis using the “cut-to-The-light” technique.

Methods

Case of a 54 year-old female patient who underwent a right percutaneous nephrolithotomy to treat a staghorn calculus with two subsequent complimentary ureteroscopies complicated by a severe proximal ureteral obstruction. An antegrade flexible uretereroscope and a retrograde rigid ureteroscope were used to locate the stenosis. With the aid of a 365-µm Ho: YAG laser fiber (settings 0.4 J, 12 Hz), we managed to successfully create a small incision in the stenotic lesion, the rigid ureterscopy light was clearly seen by the antegrade flexible ureteroscope and a through-and-through guidewire was then placed, securing the ureter. Ureteral dilatation was then performed followed by a full thickness incision of the ureteral stenosis. A single 8Fr, 28 cm double J ureteral stent was finally placed after stone fragmentation.

Results

The operating time was 200 mins. No blood loss. No fever or signs of UTI were seen shortly after the operation. The Foley catheter was successfully removed at day one post-op. The hospital stay was short of only 2 days.

Conclusion

The “cut-to-the-light” technique is a new application in the arsenal of ureteral stricture treatment that has been scarcely described in the literature before. The use of this method seems to offer excellent outcomes thus demonstrating the importance of this minimally invasive technique as an alternative to conventional invasive methods used. We believe that studies with larger samples and longer follow up are needed in order to fully determine the benefits of this method and to assess and reveal its suitable application and its drawbacks.

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.

Robot-assisted Transplant Ureteral Repair to Treat Transplant Ureteral Strictures in Patients after Robot-assisted Kidney Transplant: A Case Series

OBJECTIVE

To describe the use of robotic-assisted transplant ureteral repair (RATUR) for treating transplant ureteral stricture (TUS) in 3 patients who had undergone robot assisted kidney transplant (RAKT).

METHOD

We reviewed the medical records of 3 patients who experienced TUS after RAKT and who underwent RATUR between 2017 and 2020. The patients' RAKT, post-transplant clinical course, endourological interventions, reoperation, and recovery were assessed.

RESULTS

All patients diagnosed with TUS presented with deterioration of kidney function after RAKT. Method of diagnosis included ultrasound, antegrade ureterogram, and CT scan. All 3 patients had a short (<1 cm) area of TUS and underwent RATUR. For 2 patients, distal strictures were bypassed with modified Lich-Gregoir ureteroneocystostomy reimplantation. One patient was treated with pyelo-ureterostomy to the contralateral native ureter. No intraoperative complications, conversions to open surgery, or significant operative blood loss requiring blood transfusion for any patient were observed. Also, no patients had urine leaks in the immediate or late postoperative period. After RATUR, 2 patients developed Clavien grade II complications with rectus hematoma or urinary tract infection.

CONCLUSION

RATUR is a technically feasible operation for kidney transplant patients with TUS after RAKT. This procedure may provide the same benefits of open operation without promoting certain comorbidities that may occur from open surgical procedures.

Biodegradable Stent with mTOR Inhibitor-Eluting Reduces Progression of Ureteral Stricture

In this study, we investigated the effect of mTOR inhibitor (mTORi) drug-eluting biodegradable stent (DE stent), a putative restenosis-inhibiting device for coronary artery, on thermal-injury-related ureteral stricture in rabbits. In vitro evaluation confirmed the dose-dependent effect of mTORi, i.e., rapamycin, on fibrotic markers in ureteral component cell lines. Upper ureteral fibrosis was induced by ureteral thermal injury in open surgery, which was followed by insertion of biodegradable stents, with or without rapamycin drug-eluting. Immunohistochemistry and Western blotting were performed 4 weeks after the operation to determine gross anatomy changes, collagen deposition, expression of epithelial–mesenchymal transition markers, including Smad, α-SMA, and SNAI 1. Ureteral thermal injury resulted in severe ipsilateral hydronephrosis. The levels of type III collagen, Smad, α-SMA, and SNAI 1 were increased 28 days after ureteral thermal injury. Treatment with mTORi-eluting biodegradable stents significantly attenuated thermal injury-induced urinary tract obstruction and reduced the level of fibrosis proteins, i.e., type III collagen. TGF-β and EMT signaling pathway markers, Smad and SNAI 1, were significantly modified in DE stent-treated thermal-injury-related ureteral stricture rabbits. These results suggested that intra-ureteral administration of rapamycin by DE stent provides modification of fibrosis signaling pathway, and inhibiting mTOR may result in fibrotic process change.