**4. New materials**

New materials include metal stents that are designed to keep the ureter open despite extrinsic ureteral compression secondary to lymphadenopathy due to malignancy. Ureteric obstruction may result in decreased renal function, pain, or infection requiring urinary diversion (Chitale, Scott-Barrett et al. 2002; Allen, Longhorn et al. 2010). As these stents must remain in place for long periods of time, they require frequent exchanges because they are susceptible to infection and encrustation with increased indwelling time. The goal in this patient population is to develop a stent that maintains ureteral patency during extrinsic compression, is soft to minimize discomfort, and is resistant to encrustation and infection.
