Prostatic stent
A prostatic stent is a stent used to keep open the male urethra and allow the passing of urine in cases of prostatic obstruction and lower urinary tract symptoms (LUTS). Prostatic obstruction is a common condition with a variety of causes. Benign prostatic hyperplasia (BPH) is the most common cause, but obstruction may also occur acutely after treatment for BPH such as transurethral needle ablation of the prostate (TUNA), transurethral resection of the prostate (TURP), transurethral microwave thermotherapy (TUMT), prostate cancer or after radiation therapy. Classification. There are two types of prostatic stent: temporary and permanent. Although a  permanent prostatic stent is not a medical treatment, it falls under the classification of a surgical procedure. Placement of a permanent prostatic stent is carried out as an outpatient treatment under local, topical or spinal anesthesia and usually takes about 15–30 minutes. A temporary prostatic stent can be inserted in a similar manner to a Foley catheter, requiring only topical anesthesia. Society. Legal approval in the United States. At the present time, there is one temporary prostatic stent that has received U.S. Food and Drug Administration (FDA) approval. The Spanner temporary prostatic stent maintains urine flow and allows natural voluntary  urination. The prostatic stent is a completely internal device and can be inserted and removed as easily as a Foley catheter. It permits normal bladder and sphincter functioning and can be worn comfortably by patients. The temporary prostatic stent is typically used to help patients maintain urine flow after procedures that cause prostatic swelling, such as brachytherapy, cryotherapy, TUMT, TURP. It has also become an effective differential diagnostic tool for identifying poor bladder function separate from prostatic obstruction. Research. Permanent stents are often metal coils, which are inserted into the male urethra. The braided mesh is designed to expand radially , applying constant gentle pressure to hold open the sections of the urethra that obstruct the flow of urine. The open, diamond-shape cell design of the stent allows the stent to eventually become embedded in the urethra, thus minimizing the risk for encrustation and migration. Permanent stents are used to relieve urinary obstructions secondary to benign prostatic hyperplasia (BPH), recurrent bulbar urethral stricture (RBUS), or detrusor external sphincter dyssynergia (DESD). The main motive for removal of permanent stents is worsening of symptoms even with device fitted. Other reasons have been migration, clot retention, hematuria, and urinary retention. The only FDA  approved permanent stent is the Urolume. Usually, permanent stents are used only for men who are unwilling or unable to take medications or who are reluctant or unable to have surgery. Most doctors do not consider permanent stents a viable long-term treatment for most men.