Use of memokath, a second generation urethral stent for relief of urinary retention in male spinal cord injured patients

Abstract

Memokath (Engineers & Doctors A/S, Hornbaek, Denmark) a second genera tion urethral stent composed of titanium nickel alloy with shape memory effect was deployed in 10 male spinal cord injured patients with urinary retention. The stent was inserted under sterile conditions via a delivery catheter under fluoroscopic control in seven and with the aid of a flexible cystoscope in three. The proximal end of the stent was positioned at the bladder neck and 50 ml of normal saline at 45°C was flushed through the stent which resulted in expansion of the distal most four coils of the stent in the proximal bulbar urethra; thus the internal sphincter (bladder neck) and external sphincter zone were kept open by the stent. Urethral stenting helped to achieve complete vesical emptying in all 10 patients. The complications included transient autonomic dysreflexia in two, transient urinary retention due to blood clot in one, and acute urinary tract infection in one patient. With a follow up of 3-7 months, all 10 patients have been aysmptomatic, with residual urine of less than 50 ml. There has been no migration or blocking of the stent. However, these stents require replacement at 12-18 months, but it is a short procedure as the Memokath, when cooled with saline at 4°C, becomes supersoft, enabling its easy and nontraumatic removal. As these stents produce no permanent effect upon the lower urinary tract and their removal is quick, safe and atraumatic, we prefer the second generation nickel titanium alloy stent to transurethral resection of bladder neck, external urethral sphincterotomy or permanent indwelling epithelialising stent, particu larly in young spinal cord injured patients who wish to retain their fertility potential.

Memokath® stents for the treatment of detrusor sphincter dyssynergia (DSD) in men with spinal cord injury: The Princess Royal Spinal Injuries Unit 10-year experience

“…If the stent is still indicated after migration has been noted, the Memokath can be repositioned. 6,12 In our series only single-ended stents were prone to migrate. This may be because the addition of the proximal funnel on a double-ended model anchors the stent more securely.…”

“…Initial complications were often minor and included persistent haematuria (3), UTI (4), acute retention (2) and migration (3). Complications that did not present until later often contributed to removal and included significant stent migration (7), encrustation or blockage (14) and severe or complicated UTI (6).…”

“…It has been suggested that it is possible to electro-ejaculate a patient with a distally placed stent that does not obstruct the ejaculatory ducts; however, more recently this approach has fallen out of favour. 6,20 Although a feasible option in selected patients, wall stents are difficult to remove, running the risk of urethral damage, and therefore they are not an ideal temporary measure.…”

“…The indications for insertion ( Figure 2) were for dysreflexic symptoms (15), high residual urine volumes and subsequent recurrent or persistent urinary tract infection (UTI) (17), for protection of the upper tracts (6) or to predict outcome following TUS (1). All stents ( Figure 1) were inserted under direct vision using a rigid (028T, 028TW, 045TW) or a flexible cystoscope (028SW).…”

“…Initial reports of Memokath usage (in the prostatic urethra) appeared promising in the short term. [4][5][6] However, others have found that Memokaths are not without complication and should be used with caution. 7 …”