The surgical management of LUTS or urinary retention secondary to BPH is not without risks, especially in the older patient or those with significant co-morbidities. The urethral stent was developed for these patients as an alternative to long-term urethral or suprapubic catheterization. Stents, such as the Urolume, which allow epithelial incorporation, are troubled by high rates of infection, encrustation and migration. Also, epithelial in-growth can cause luminal narrowing to an extent which requires stent removal which can be an extremely difficult procedure.
The Memokath stent is manufactured from a nickel-titanium alloy that has the property of “shape-memory”; this describes a process by which a deformed piece of alloy is restored to its original shape by heating. When a Memokath stent is placed in the prostatic urethra, it is flushed with warm saline causing it to lock into position. Flushing it with cold saline renders the stent soft, which facilitates its removal.
A recent review by J. N. Armitage and colleagues from London was performed to examine the available data from clinical trials on the effectiveness of the Memokath stent when used for the treatment of BPH. The review is published in the October 2006 issue of BJU Int.
In all, 14 cases series described the use of the Memokath stent in 839 men with BPH. All patients were at high operative risk. Most studies were of poor quality with an inadequate follow-up. Treatment failure rates were 0-48% but the duration follow-up was often unclear. Treatment failures were defined the need for stent removal, replacement or repositioning or for inadequate symptom score improvement. Stent migration was the most commonly reported cause of failure. The stent had a low rate of immediate failure due to malpositioning of only 4%. Stent insertion was associated with a reduction in the IPSS of 11-19 points.
In all, the inadequacy of study design, follow-up and lack of standard measures of failure makes for a meta-analysis of the available data unable to be performed. No conclusions, other than the need for a more carefully designed trial, can be drawn from this review.
By Michael J. Metro, M.D.
BJU Int. 2006 Oct;98(4):806-10