The thermo-expandable metallic ureteric stent: an 11-year follow-up

To review our long-term use of the thermo-expandable metallic ureteric stent, (model 051, PNN Medical, Denmark) for ureteric obstruction, and review current reports on its use.

Data were collected prospectively on all patients who had a Memokath 051 ureteric stent inserted between November 1996 and November 2007. The standard stent, and wide and dual expansion versions were used. The stricture characteristics were recorded in a standard way. All stents were inserted by one surgeon in the UK and internationally, following a standard protocol.

In all, 74 stents were inserted into 55 patients in the study period (mean age 60 years, range 11-90). The indications for metallic stenting included primary stenting for malignancy, failed conventional open and endoscopic techniques, palliation, and where significant comorbidity limited repetitive stent changes. In 28 patients the obstruction was caused by malignancy, whereas in 27 it was caused by recurrent benign disease. The mean (range) hospital stay was 1.43 (0-7) days. Imaging after insertion showed normal or improved functional drainage in all but three patients, with immediate complications including urinary extravasation (one), poor thermo-expansion (one) and equipment failure (locking assembly) (one). Late complications included migration (13), encrustation (two) and fungal infections (three). In all, 14 patients needed reinsertion (mean of 7.1 months, range 1-14) after insertion for migration (eight), encrustation (two), stricture progression (three) and incorrect stent length (one). Overall, 29 patients have died with the stents in-situ. The mean (range) follow-up was 16 (4-98) months.

The thermo-expandable metallic Memokath 051 ureteric stent offers effective and durable long-term relief from ureteric obstruction, and is a safe alternative to conventional JJ stenting. In addition there is an emerging role in palliation and the primary management of ureteric strictures.