What Is a Urinary Stent?

Urethral stent implantation has been greatly developed in China in recent years. At present, the common method in clinical practice is to place a urethral stent in the urethral stricture to open the narrow or blocked urethra. This stent is made of stainless steel, synthetic fiber silicone or nickel-titanium alloy. It can be placed on the urethral stricture through cystoscopy to expand the originally narrow and closed posterior urethra. It can make most patients who have difficulty urinating place a urethral stent. After returning to urination.

Urethral stent implantation has been greatly developed in China in recent years. At present, the common method in clinical practice is to place a urethral stent in the urethral stricture to open the narrow or blocked urethra. This stent is made of stainless steel, synthetic fiber silicone or nickel-titanium alloy. It can be placed on the urethral stricture through cystoscopy to expand the originally narrow and closed posterior urethra. It can make most patients who have difficulty urinating place a urethral stent. After returning to urination.

1. Urethral Stent 1. Introduction

Prostatic hyperplasia is a common and frequently-occurring disease in middle-aged and elderly men, with an incidence rate of 50% to 90% over the age of 50, which generally causes urethral stricture and urinary retention. Existing treatments such as open surgery or cavity surgery have a high risk. Even patients cannot accept surgery at all, and drug treatment is difficult to effectively relieve the symptoms of obstruction. The suprapubic bladder fistula or indwelling catheter is given to the patient. Life brings inconvenience, inevitable retrograde urinary tract infections and various complications, which not only affects the survival time of patients, but also reduces the quality of life of patients. In addition, benign urethral hyperplasia, urethral neoplasia, and posterior urethral stricture and obstruction can also cause urinary retention.

The advent of metal stent has provided new treatment technology to solve this difficult problem. Urethral stent implantation has been greatly developed in China in recent years. At present, the common method in clinical practice is to place a urethral stent in the urethral stricture to open the narrow or blocked urethra. This stent is made of stainless steel, synthetic fiber silicone or nickel-titanium alloy. It can be placed on the urethral stricture through cystoscopy to expand the originally narrow and closed posterior urethra. It can make most patients who have difficulty urinating place a urethral stent. After returning to urination.

Figure 1. Schematic of urethral stent

Figure 2. Schematic diagram of urethral stent implantation site

2. Urethral stent 2. Classification of metal urethral stent

Nickel-titanium memory alloy expandable urethral stent has excellent biocompatibility and corrosion resistance, and has peculiar memory characteristics and super elasticity. The stent is softened at 0-10 ° C (ice water), within a certain range. The shape can be changed, and the stent can be delivered into the narrow area of the body through the conveyor. Under the body temperature, the stent can immediately return to the original shape, generating a continuous soft radial expansion force, acting on the urethral wall, restoring the stenosis and unblocking the urethra The inner wall is tightly attached, allowing the mucosa to be embedded, promoting epithelial cell coverage and preventing the formation of stones.

(1) According to the different methods of wire weaving, it is divided into woven urethral stent and woven urethral stent. Choose different diameter stent according to the patient.

a. Woven urethral stent

Made of titanium-nickel memory alloy material, it has good supporting force and shaping force. The stent is tightly integrated with the urethral stricture. It is characterized by high-temperature sizing and good biocompatibility. The stent stimulates the urethral epithelium less (such as Figure 3A).

b. Braided urethral stent

Made of titanium nickel memory alloy material, it has good supporting force, shaping force and good weaving characteristics. The stent is tightly integrated with the urethral stricture (see Figure 3).

Figure 3. Schematic diagram of urethral stent

(2) Classification based on implantation time

a. Permanent bracket

The permanent stent adopts a tubular mesh design, mostly composed of titanium, nickel and its alloys, and has good biocompatibility.It can be covered by the urethral epithelium after implantation in the urinary tract, and can be completely completed in 3 to 6 months. Epithelialization.

b. Temporary support

Unlike the permanent stent, it plays a supporting role in the urinary tract rather than embedded in the urethral wall. Absorbable biodegradable stent is a temporary stent developed in recent years. It consists of high molecular glycolic acid polymer (PGA) or lactic acid polymer (PLA). It has the characteristics of good histocompatibility, small inflammatory response, low infection rate, no crystals on the surface, and no need to remove or replace.

3. Urethral stent 3. How to place urethral stent

The urethral stent placement can be performed under cystoscopy, X-ray or B-ultrasound, using different stent implanters (as shown in Figure 4A). Various inserter specifications, select according to your needs.

(1) Operation under cystoscope: conventional disinfection of 0-degree cystoscope and optical fiber. Local or epidural anesthesia is performed on the patient, and stenosis is checked with cystoscopy. An appropriate stent is selected based on the measured urethral stricture length. Withdraw the cystoscope and insert the cystoscope into the hole in the holder with the stent. The stented device is then inserted into the urethra with the cystoscope over the narrow section. Place the stent under direct vision. After placement, observe the position of the stent. If the position of the stent is not suitable, adjust it with biopsy forceps.

(2) Operate under X-ray or B-mode: Insert the device (as shown in Figure 4B) into the human urethra along the guidewire. When the device passes through the narrow section and the proximal position is 10 mm higher than the predetermined position, When the distal position exceeds the distal end of the narrow segment, open the safety lock, hold the rear handle to remain stationary, and under X-ray or B-ultrasound, retract the front handle to release the bracket. Exit the inserter.

(3) Hybrid method: If the above methods can be combined with each other, they can achieve better results than the single placement method and improve the success rate of surgery.

Figure 4. Urethral stent implanter

4. Urethral stent 4. Common complications after stent placement

(1) Hematuria: Intermittent hematuria may occur after stent placement, which may be related to the patient's long-term use of a urethral catheter, which may cause urinary tract infection and mucosal erosion. After the stent is implanted, the stent is exposed, which further aggravates urethral mucosal damage.

(2) Lower urinary tract infection: This is related to the presence of residual urine volume, bare stent, and decreased overall or local resistance of the patient.

(3) Urinary incontinence: This is due to improper placement of the stent, and the lower end of the stent crosses the membrane.

(4) Reverse ejaculation: The reason is that the front end of the stent is close to the bladder neck, which results in that the inner urethral opening cannot be closed during ejaculation.

(5) Urinary retention: Urinary retention still occurs after placement of a prostate stent. There are usually five cases: a. Postoperative blood clot obstruction; b. Patients with chronic chronic urinary retention who have long-term urine tubes and bladder before surgery. Detrusor fibrosis; c. The upper part of the prostate urethra is not covered by the stent; d. Granular tissue or epithelial hyperplasia in the rack causes stenosis; e. The prostate tissue continues to grow beyond the ends of the stent and blocks the stent.

A large number of clinical reports show that the short-term efficacy of stent therapy is accurate, but its therapeutic effect has a tendency to decline over time, and there are still some issues to be addressed: 1) Prostatic hyperplasia is a benign progressive disease. As the age increases, it may exceed the range supported by the stent when it continues to increase. 2) After the stent is implanted, there will be different degrees of granulation tissue and epithelial proliferation. 3) How to better grasp the indications and contraindications, choose the appropriate size and length of the stent and place it in the appropriate position.

Urethral stent extended reading:

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