During my training, I was taught that splints were used externally, for instance to stabilize fractures, whereas stents were for internal use. A recent biographic paper on Dr. Charles Stent, a dentist who invented stents around 1856 in England said that it was invented to get dental impressions, originally called Stent's mass (8). This formulation was also used as a tissue expander for neck and knee surgery and later to hold tubes open and in facial reconstruction during the WWI. The ancestry of the stent would appear to be by way of dentistry and plastic surgery.
Prostatic stents are divided into three categories: prostate springs, which include Urospiral, Prostacath, Prostacoil stents; self-expandable stents such as the Urolume; and balloon-expandable stents such as the Titan and the newer Memotherm, including intraurethral catheters and the new biodegradable ones. The available literature concerning the various types of stents consist of small series with short follow-up and no controls. There are, however, excellent recent reviews (9,10).
The use of ureteral stents began in the 1960s with the use of Silastic tubing to keep obstructed ureters open. It was used more as an indwelling catheter than as a stent to hold scarred ureters open. The tubing was passed from below. In 1969, stents were placed in peripheral arteries to prevent re-stenosis after balloon angioplasty in the peripheral vascular system (11). Since that time, stents have been adapted for use in every vessel, duct, and tube in the body.
The first described use of intraprostatic stents in the treatment of prostatic obstruction dates to 1980 when Fabian described placing a temporary stent through the prostate for high-risk patients (the urospiral) (12,13). The urospiral reportedly had problems with migration, encrustation, and recurrent infections, and did not allow cystoscopy.
The second permanent prostatic stent system was reported by Chapple et al. in 1990 (14). This group had previous experience with stents for managing strictures in the male urethra and thought it was a logical extension of the procedure to use it in prostate obstruction. The stent was made of wire mesh that became epithelialized in 6-8 mo. Most of the patients had urinary retention from BPH and were poor operative can didates. Patients with atonic neurogenic bladders were excluded. The stent was successful in 11 of 12 patients. One patient was unhappy with the procedure because of persistent frequency of urination and was found to have severe detrusor instability. In two patients, encrustations of the proximal end of the stent developed, which were dislodged and removed endoscopically. The same group's expanded experience of 54 patients was reported in 1993 (15). In this group, 93% were able to void, and 74% had no to minimal voiding symptoms. Encrustations developed in 26% and 6 of 54 required subsequent removal.
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