BJU International 2002 89 (4cr), 466

T. Hamasaki, Y. Hashimoto and T. Nishimura*

Department of Urology, Kitamurayama Public Hospital, Higasine, Yamagata, and * Nippon Medical School, Sendagi, Bunkyo, Tokyo, Japan

Method 

References 

Authors 

Patients with urinary retention and whose lower urinary tract obstruction cannot be surgically treated because of severe complications must have an indwelling urethral catheter placed. Recently, such high-risk patients have been managed using new methods like hyperthermia [1], laser therapy [2–3], balloon dilatation of urethra and urethral stenting [4–8]. The Memokath catheter (Engineers & Doctors A/S, Hornbaek, Denmark) is made from a shape-memory nickel-titanium alloy of high biocompatibility, to allow the expansion of the single-wire coiled stent (by warming). This feature makes it possible to locate the stent in the correct part of the urethra and then expand it. The combination of material and design makes the stent easy to handle both for implantation and removal, and provides a better solution than conventional coiled stents. Placing the stent in the correct position is the key to successful treatment; various arrangements are incorporated into the procedure for both removable and permanent stents. In practice, the stent can be implanted easily but sometimes thermal setting in the correct position is difficult. We report a method of correcting the position of the stent once it is implanted.

Indications 

References 

Authors 

The method was used in 17 patients (mean age 82 years, range 54–92) treated between April 2000 and April 2001. The stent was implanted in these patients because they had urinary retention from BPH or prostatic carcinoma (15) or a neurogenic bladder (two), for which pharmacotherapy had not been effective. The patients had other general complications (cardiovascular, neoplasms, spine injury and cerebral infarction) which prevented invasive surgery. The mean (range) duration of retention was 8.1 (2–19) months.

The Memokath stent is designed to expand and become fixed in the urethra when warmed to 45°C and to soften for easy removal when cooled to <10°C. The stents are available in lengths of 30–70 mm in increments of 10 mm, and as a standard type (outer diameter 22 F, expanding portion 34 F) or as a thick stent (outer diameter 24 F, expanding portion 44 F).

For implantation, the urethral mucosa is locally anaesthetized using lidocaine jelly, and urethrography undertaken to select the appropriate length of stent. The stents are implanted under radiographic guidance. Before placing the stent a 10 F renal pelvic balloon catheter is passed through an implantation sheath. The stent is inserted into the urethra, using the balloon catheter as a guide, and placed in the correct position beyond the urethral sphincter, under radioscopy (Fig. 1). Urethrography is used after placing to confirm that the stent does not interfere with the urethral sphincter. If the urethrogram shows that the position is incorrect a 10 F renal pelvic balloon is passed through an implantation sheath. After confirming that the renal pelvic balloon is through the stent, the balloon is dilated with 0.5 mL physiological saline. It is then possible to hold the urethral stent between the balloon and the implantation sheath, so that the urethral stent can be moved freely to the correct position (Fig. 2).

The stents used in the present patients were the thick type, 30 mm long in three patients, 40 mm in eight and 50 mm in six. The time required for placement was longer for the first two patients (40 and 30 min) than for the others (15–20 min). The stent was incorrectly placed in the first patient, and was displaced into the bladder when there was an attempt to re-position it using a cystoscope; the complete procedure had to be repeated and thus the present method was developed to re-position incorrectly placed stents thereafter.

After the procedure all the patients were able to void with no need for balloon catheters in situ; however, this report concerns only the technique, and the evaluation did not include quantitative assessments of urination, e.g. CMG or uroflowmetry. None of the patients required removal of the Memokath for subsequent complications or side-effects, and although some were incontinent, they did not wish to have the stent removed. The patients continue to be followed biannually with lower abdominal X-ray and endoscopy, to assess the need for stent replacement if there are stone deposits or other complications; the current mean (range) follow-up is 21.2 (6–25) months. This technique of using a ureteric balloon catheter to adjust the position of the stent is simple and quick. The experience with the first patient highlighted the difficulties of using an endoscope with simple grasping forceps.

Indications 

Method 

Authors 

Indications 

Method 

T. Hamasaki, MD, Chief Clinical Assistant, Urologist.

Y. Hashimoto, MD, Clinical Assistant, Urologist.

T. Nishimura, MD, Professor, Chairman, Urologist.