746 Single-Centre Experience with Three Metallic Ureteric Stents (Allium URS, Memokath-051 and Resonance) for Chronic Ureteric Obstruction

Aim To evaluate efficacy of Allium URS, Memokath 051 and Resonance metallic ureteric stents as an alternative to polymer stents/nephrostomy in managing chronic ureteric obstruction (CUO). Method Retrospective analysis of consecutive patients with CUO managed with Allium URS, Memokath-051 or Resonance (September 2015/July 2020). Baseline patient variables (age, gender, underlying aetiology, ASA) and stricture characteristics (length, level, continuity) were recorded. Intra- and post-operative clinical and radiological follow-up assessments at 6 weeks, 3 months and then every 6 months, as well as any emergency attendances, were reviewed for placement success, stent complications, serum creatinine, and mortality. Outcomes included placement success rate, functional stent survival, and mean renal function. Results Overall, 129 stent insertion episodes (SIEs) (Allium URS: 23, Memokath 051: 48, Resonance: 58) occurred in 76 patients (Allium URS: 16; Memokath-051: 31; Resonance: 29). Placement success was high (Allium URS: 95.7%; Memokath-051 and Resonance: both 100%). Median functional stent survival was 11.4 months for Allium URS, 5.5 months for Memokath-051 and 11.7 months for Resonance. 47.8% of Allium URS SIEs (11/23), 64.6% of Memokath-051 SIEs (31/48) and 19% of Resonance SIEs (11/58) experienced complication (most frequently obstruction followed by migration and infection). There were no complications for Resonance SIEs for benign indication. In the first year following SIE, serum creatinine ranged from +21.3% to + 46.7% for Allium URS, -7.8% to + 8.9% for Memokath-051, and -9.4% to + 27.3% for Resonance. Conclusions Allium URS, Memokath 051 and Resonance metallic ureteric stents are all viable management options of CUO. Resonance was particularly efficacious for patients with benign aetiology.

647 Management of Malignant Upper Urinary Tract Obstruction

Background Malignant Upper Urinary Tract Obstruction (MUUTO) is a common emergency presentation. These are often complex patients and require multiple specialty input to make time-critical decisions. There are currently no national guidelines for the management of MUUTO, a review was conducted to assess the management and outcomes of MUUTO. Aim To agreed and review a pathway for patients with MUUTO in order to streamline patient care and to review the management. Method The pathway was devised by several consultants at Oxford University Hospital. Through retrospective data collection, the outcomes over six months were reviewed. Results Over the six-month period 49 interventions were performed for MUUTO; 44 Percutaneous Nephrostomy (PCN) and five cystoscopies with retrograde ureteric stents (RUS). Patients were admitted to urology in 45% of cases and oncology in 39%. The obstruction was located above the pelvis in 16 (33%) of the cases and within the pelvis in 25 (51%). The most common cancers causing obstruction were bladder cancer (41%), prostate (16%), and colorectal (14%). MDT advice was sought in 63% of cases. The mean time from diagnosis to the intervention was four days. Of the five retrograde inserted ureteric stents, four were unsuccessful and the patients proceeded to PCN. At the conclusion of data collection, 26 (53%) patients had died. Discussion The most striking findings were the high failure rate of RUS and the overall poor prognosis of MUUTO. As such this review suggests that more patients should proceed directly to PCN for decompression.

Effect of Metallic Ureteric Stents on Magnetic Resonance Imaging: Implications for Malignant Ureteral Obstruction

Metallic ureteric stents are increasingly used for the management of malignant ureteric obstruction, a commonly encountered complication in urological and other malignancies. However, there has been limited evaluation of complications associated with these stents, including those that might arise from the use of magnetic resonance imaging (MRI). While most devices are deemed nominally “MRI-safe,” their implication on the quality of imaging produced has not been evaluated in clinical trials, and in our practice, significant artefact has been encountered with some ureteric stents—specifically, the Teleflex Rüsch DD tumour stent—compromising image quality and diagnostic certainty.