Prostate Adenoma - Surgery

Among the variety of methods currently offered for the treatment of prostate adenoma (prostate gland), the operation "open adenomectomy" remains the most radical method of treating this disease.

The rapid development of conservative therapy methods for prostate adenoma has resulted in a revision of the indications for surgical treatment. Currently, surgery is considered absolutely indicated only in the presence of complications of the disease. According to the recommendations of the 3rd meeting of the International Coordination Committee on the Problem of Prostate Adenoma (1995), absolute indications for surgical treatment have been determined:

• urinary retention (inability to urinate after at least one catheterization):
• recurrent massive hematuria associated with prostate adenoma;
• renal failure caused by prostate adenoma;
• bladder stones;
• recurrent urinary tract infection due to prostate adenoma;
• large diverticulum of the bladder.

In addition, the operation is indicated for patients whose prognosis for the course of prostate adenoma (prostate gland) does not allow one to expect a sufficient clinical effect from conservative methods (the presence of an enlarged middle lobe of the prostate, severe infravesical obstruction, a large amount of residual urine) or if the drug treatment already being carried out does not give the necessary result. In other cases, conservative treatment may be recommended as the first stage.

Surgery for prostate adenoma (prostate gland) can be undertaken for emergency indications or on a planned basis. Emergency adenomectomy means its performance outside of planned work for urgent indications. Emergency adenomectomy is emergency, when it must be performed within 24 hours from the moment of acute onset of the disease (complication), and urgent, when it must be performed no later than 72 hours from the moment the patient is admitted to the urology department.

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Operation "emergency adenomectomy"

The operation "emergency adenomectomy" is indicated:

• in case of life-threatening bleeding;
• in case of acute urinary retention and the general satisfactory condition of the patient.

Acute urinary retention rarely resolves on its own. In most cases, bladder catheterization is a necessary measure.

Emergency adenomectomy is contraindicated in the presence of an acute inflammatory process in the urinary system, concomitant diseases in the decompensation stage (stage III hypertension, chronic coronary heart disease, diabetes mellitus, etc.), and terminal stage chronic renal failure.

The nature and purpose of preoperative preparation determine those deviations in the patient's health that must be eliminated to reduce the risk of complications and the severity of the postoperative period. In the presence of changes in the cardiovascular and respiratory systems, appropriate drug therapy is administered. Much attention is paid to the treatment of concomitant kidney and urinary tract infections. For this purpose, patients are prescribed uroantiseptics and broad-spectrum antibiotics according to the sensitivity of the urine microflora, giving preference to the least nephrotoxic drugs. The state of the blood coagulation system is examined and appropriate treatment is prescribed to prevent postoperative complications. In the presence of diabetes mellitus, antidiabetic therapy is administered, and, if necessary, patients are transferred to insulin injections. In the presence of concomitant chronic prostatitis, it is important to undergo an appropriate course of therapy before surgery.

A detailed description of the techniques of various methods of surgical treatment of prostate adenoma is given in special monographs and manuals on surgical urology, therefore in this guide we will consider only general and fundamental provisions.

Depending on the access to the prostate, a distinction is made between transvesical, retropubic, and transurethral adenomectomy.

Transurethral endourological treatment of prostate adenoma

Over the last decade, TUR of the prostate adenoma has been increasingly introduced into clinical practice. The use of transurethral surgery has significantly expanded the indications for surgical treatment of patients with prostate adenoma and concomitant intercurrent diseases, who until recently were doomed to lifelong urinary diversion by cystostomy. Improvements in endoscopic equipment and accumulated experience have expanded the capabilities of TUR and allowed this method to be used in patients with large prostate adenoma (more than 60 cm ² ), as well as in the case of retrotrigonal growth, which was previously a contraindication to this operation. TUR of the prostate can be performed both on a planned basis and for emergency indications (in acute urinary retention).

Among the various methods of treating prostate adenoma, TUR currently occupies a leading place, which is undoubtedly due to its low trauma and high efficiency. This method of surgical treatment has a number of advantages over open surgery.

• No soft tissue trauma when accessing the prostate.
• Strictly controlled hemostasis during surgery.
• Shorter rehabilitation of patients in the postoperative period.
• Possibility of surgical treatment in individuals with intercurrent diseases.

To carry out TUR, certain instrumental and technical support is required.

In the early postoperative period of TURP, bleeding may also develop due to local fibrinolysis in the prostate tissue or systemic intravascular blood coagulation.

Late bleeding (on the 7th-8th, 13th-14th, 21st day) is most often associated with the discharge of postoperative scab. They usually have an intermittent course and in most cases they can be stopped conservatively (hemostatic therapy, installation of a urethral catheter with tension). If bleeding does not stop within 24 hours, repeated endoscopic intervention is indicated, aimed at coagulation of bleeding vessels. In the pathogenesis of late bleeding, an important role is played by the presence of chronic infection in the prostate, as well as purulent-inflammatory complications that arise in the immediate postoperative period, contributing to the inhibition of wound surface healing processes and early discharge of the scab. Given this, all patients with a history of chronic lower urinary tract infection need preoperative preparation in the form of antibacterial therapy, taking into account the etiology.

One of the serious postoperative complications of TUR of the prostate is the development of water intoxication of the body (TUR syndrome), the frequency of which varies from 0.5 to 2%. In the pathogenesis of TUR syndrome, the main role is played by the entry of a large amount of irrigation fluid into the bloodstream during endoscopic surgery through intersected venous vessels of different calibers when using hypoosmolar solutions for irrigation of the bladder during surgery. The longer the surgery, the greater the amount of fluid sucked in and the larger the diameter of the venous trunks, the more fluid can penetrate into the venous collectors, determining the degree of water intoxication of the body. Consequently, undetected damage to the venous sinus during surgery increases the likelihood of this complication. TUR syndrome is manifested by a number of symptoms that occur in the early postoperative period (within the first day). These are bradycardia, decreased blood pressure, changes in biochemical parameters and electrolyte composition of the blood (hyponatremia, hypokalemia) against the background of hypervolemia. Several stages can be distinguished in the development of TUR syndrome. The initial manifestations that should alert the urologist already during the operation are considered to be an increase in blood pressure, the appearance of chills. If the necessary measures are not taken to correct this condition, then its sharp deterioration is noted in the future: a drop in blood pressure, massive hemolysis of red blood cells, the development of oligoanuria. general anxiety, cyanosis, shortness of breath, chest pain and convulsions. In the absence of an effect from the therapy of acute renal and hepatic failure and gross electrolyte disturbances, the patient dies.

If TUR syndrome occurs, it is necessary to carry out emergency conservative measures aimed at normalizing the water-electrolyte balance and stabilizing hemodynamics. To prevent TUR syndrome, it is necessary to:

• use only isotonic washing solutions;
• strive to reduce the time of surgery by improving visibility (use of high-quality optical equipment, video-TUR). improving the skills of the urologist;
• strictly adhere to the principles of performing TURP.

In addition, in order to prevent increased intravesical pressure, it is recommended to use resectoscopes with constant irrigation of fluid, special mechanical valves, active aspiration systems, etc.

Among the inflammatory complications encountered after TUR of the prostate, acute inflammatory diseases of the lower urinary tract and scrotal organs (urethritis, funiculitis, epididymoorchitis, prostatovesiculitis, cystitis) occupy a prominent place, the cause of which is most often associated with an exacerbation of a chronic infectious process against the background of a urethral catheter.

It is also necessary to dwell on other complications of TUR of the prostate, not the least of which are iatrogenic injuries of the urinary tract. These are injuries of the urinary bladder (perforation of the wall, damage to the triangle of Lieto), damage to the orifices of the ureters, often occurring during resection of pronounced intravesical lobes of the hyperplastic prostate, damage to the urethra and prostate, which can cause stricture of the urethra, disruption of the integrity of the external sphincter of the urethra, leading to urinary incontinence, damage to the seminal tubercle. Most often, they occur at the stage of mastering the TUR technique due to non-compliance with the technique of performing the operation, therefore, it is obvious that it is necessary to strictly adhere to all the rules of transurethral intervention and have a certain experience that allows the urologist to avoid these complications.

Among the late complications of TUR of the prostate, it is necessary to note stricture of the urethra and sclerosis of the neck of the bladder. Stricture of the urethra most often occurs in the anterior sections and is associated with three main factors: trauma to the mucous membrane when passing the endoscope through the urethra, inflammatory changes in the urethra, chemical damage to the urethra that occurred against the background of a urethral catheter. Sclerosis of the neck of the bladder after TUR of the prostate is less common than after open adenomectomy, but its incidence is relatively high (8-15%). Most often, this complication occurs in patients after TUR of small adenomas combined with chronic bacterial prostatitis.

As with other surgical interventions on the prostate, with TUR there is a risk of retrograde ejaculation, the frequency of which ranges from 75 to 93% of cases, which must be taken into account when determining surgical tactics in patients with preserved sexual function.

Transurethral Electrovaporization of the Prostate

Along with TUR, a new method of treating prostate adenoma has recently been increasingly introduced - electrovaporization (or electroevaporation) of the prostate. This method is based on the TUR technique using a standard endoscopic kit. The difference lies in the use of a new roller electrode (vaporrod, or roller), which is presented in several modifications that differ in the direction of energy distribution. Unlike TUR, with electrovaporization, in the area of contact of the roller electrode with the prostate tissue, tissue evaporation occurs with simultaneous drying and coagulation. By analogy with TUR, this operation can be called transurethral electroevaporation of the prostate.

The current strength used in electrovaporization is 25-50% greater than in standard TUR. At the same time, the depth of coagulation in transurethral electrovaporization is approximately 10 times greater than in TUR, which significantly reduces tissue bleeding during surgery. This distinguishes this treatment method from TUR, which is accompanied by bleeding of varying intensity during surgery.

Since the technique of transurethral electroevaporation surgery does not involve obtaining material for histological examination to exclude latent prostate cancer, all patients should undergo a blood serum test for PSA content. In case of its increase before the operation, preliminary fine-needle multifocal prostate biopsy is indicated.

Indications for transurethral electroevaporation are the same as for TUR. Most often, epidural anesthesia is used to ensure adequate pain relief during transurethral electroevaporation. After the operation, a urethral catheter is installed for 1-2 days.

The results of using transurethral electroevaporation have proven its effectiveness for small and medium-sized prostates, which allows us to consider this method of treatment as an independent one for this category of patients.

Electroincision of prostate adenoma

Along with transurethral electroresection and electrovaporization, another method of electrosurgical treatment has recently found wide application - electroincision of the prostate. The method was proposed by E. Beer in 1930, but it was not widely used until the 1970s, when it began to be used relatively widely instead of TUR in patients with prostate adenoma and sclerosis of the bladder neck. Unlike TUR, which involves electrosurgical removal of tissues in a circle using a cutting loop, incision does not remove the tissues of the prostate and bladder neck, but rather performs a longitudinal dissection. Thus, incision of the prostate obviously requires a prostate biopsy in the preoperative period if a malignant process is suspected.

Indications for prostate dissection:

• young age of the patient with preserved sexual function;
• small prostate volume (the weight of the gland should not exceed 20-30 g);
• the distance from the seminal tubercle to the neck of the bladder is no more than 3.5-4.0 cm:
• predominantly intravesical growth of adenoma;
• absence of malignant lesions of the prostate.

Electroincision is performed at 5, 7 and 12 o'clock on a conventional clock face with a spear-shaped electrode. The incision is made through the entire thickness of the hyperplastic tissue to the surgical capsule from a point located 1.5 cm distal to the ureteral orifice. At the end of the operation, bleeding vessels are coagulated, and the bladder is drained with a urethral catheter for 24 hours.

The advantage of this technique over others, where the prostate is dissected at 4, 6 and 3, 8 and 9 o'clock on the conventional clock face, is that the incision is performed along the natural interlobular boundaries of the prostate, which is associated with less tissue trauma and the risk of bleeding. However, a final choice between dissection and resection can only be made with urethrocystoscopy, which allows for a clear determination of the size of the prostate and the shape of its growth.

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Prostate adenoma - operations: laser surgery methods

The history of lasers in urology spans over 30 years. The basis for using laser technologies in the treatment of prostate adenoma was the desire to improve the results of TUR by reducing the number of complications, primarily hemorrhagic ones. Laser energy is used for coagulation, dissection and evaporation of tissue. Up to 60-70% of laser energy is absorbed, and 30-40% is reflected by tissues. The absorption of laser radiation, the tissue effects it causes and the depth of damage are determined by the wavelength and power. The achieved thermal effect also depends on the type of tissues exposed, their combination and vascularization.

It should be borne in mind that high-power radiation focused in a small volume, even with a relatively short application time, can quickly lead to carbonization of the tissue, preventing further treatment. On the other hand, lower energy density with a longer exposure time ensures deep coagulation.

Coagulation and evaporation are basic techniques of laser surgery for prostate adenoma. Treatment can be performed using contact and non-contact methods.

• Laser vaporization of the prostate.
  • Contactless (Side-fire).
  • Contact.
• Laser coagulation of the prostate.
  • Contactless (Side-fire).
  • Contact.
  • Interstitial.

A combined method is also used, which involves the use of these techniques simultaneously. A separate method is interstitial laser coagulation of the prostate.

For remote (non-contact) endoscopic laser coagulation, fiber-optic fibers such as Urolase (Bard), Side-fire (Myriadlase), ADD (Laserscope), Prolase-II (Cytocare), Ablaster (Microva-sive) are used with special tips that direct the laser beam at an angle to the longitudinal axis of the fiber. In this case, the angle of incidence in various designs ranges from 35° to 105°. In foreign literature, the method is called visual (endoscopic) laser ablation of the prostate (VLAP or ELAP). The non-contact method differs from the contact method in lower energy concentration, since the removal of the fiber tip from the tissue surface increases the dispersion of the laser beam and reduces the energy density.

Transurethral contact laser vaporization of the prostate under endoscopic control is performed by direct contact of the fiber tip with the tissue. In this case, due to the creation of a high energy density at the point of contact of the fiber with the tissue, a high temperature is achieved, leading to the evaporation effect. For contact vaporization, fibers with special sapphire tips or light guides with a lateral beam direction are used, the tip of which is protected by a special quartz cap: STL, Ultraline, Prolase-I.

The advantage of the method is the possibility of one-stage removal of hyperplastic tissue under visual control. However, this procedure requires more energy and is longer than the contactless method. Thus, energy costs for an adenoma weighing 20-40 g are from 32 to 59.5 kJ, and with a weight of more than 40 g they can reach 62-225 kJ with a procedure duration of 20 to 110 minutes. Usually, a power of 60-80 W is used.

The incidence of intra- and postoperative bleeding, urinary incontinence, sexual dysfunction and urethral strictures with contact vaporization is significantly lower than with TUR. One of the most common complications of the method is prolonged postoperative urinary retention, which occurs in 5-8% of patients.

The combined technique involves a combination of contact and non-contact methods. The operation is divided into 2 stages. First, the prostate is dissected using the contact method at 5, 7, and 12 o'clock on the conventional clock face, and then the hyperplastic tissue is coagulated at 2, 6, and 10 o'clock, respectively. The method gives good results with a small number of complications.

Recently, there have been reports of a new endoscopic method of resecting prostate adenoma using a holmium laser. The technique of the operation differs significantly from that described above. The holmium laser provides a better evaporation effect with a smaller (up to 2 mm) coagulation depth, which allows it to be successfully used for tissue dissection. The method involves resecting the middle and lateral lobes of the prostate along the periphery, followed by dissection in the transverse direction and removal. This technique still needs to be studied.

The least invasive method of laser therapy for prostate adenoma is interstitial laser coagulation of the prostate, in which a light guide (5 CH) is inserted directly into the prostate tissue transurethrally under endoscopic control or transperitoneally under ultrasound guidance. For this purpose, fiber optic fibers with pointed tips are used, which diffusely disperse the laser radiation in the form of a sphere.

After the tip is inserted into the prostate tissue, it is heated for a long time (3-10 min) to 66-100 °C, induced by a low-power laser (5-20 W). The use of low energies is necessary to prevent carbonization (charring) of the tissue, which reduces the degree of penetration of laser radiation and can cause overheating and damage to the tip itself. The treatment is carried out under epidural or intravenous anesthesia. As a result of the exposure, a zone of coagulation necrosis with a diameter of up to 2.5-3 cm is formed around the tip. Depending on the size and configuration of the prostate, it is necessary to change the position of the fiber from 2 to 10 times during the procedure, which affects the total duration of the operation. The average operation time is 30 minutes. In this case, the total energy dose is from 2.4 to 48 kJ (on average 8.678 kJ).

Treatment of patients significantly reduces the severity of disease symptoms. increases Qmax, reduces Vост, and reduces prostate volume by 5-48%. After laser therapy, irritative symptoms and temporary postoperative urinary incontinence are observed less frequently than after TUR. Complications in the early postoperative period include irritative symptoms in 12.6%, bacteriuria in 35.6%, pain in 0.4%, secondary bleeding in 2.1%, and stress urinary incontinence in 0.4% of patients.

Thus, laser surgical treatment methods for prostate adenoma are clinically effective and relatively safe. The main reason limiting their distribution is economic: the cost of the equipment required for laser surgery is many times higher than that for standard electroresection or electrovaporization of the prostate.

Transurethral microwave thermotherapy

Fundamentally different processes are observed in the thermotherapy mode (45-70 °C) when the threshold of temperature tolerance of prostate cells is reached, corresponding to 45 °C. The upper temperature limit of the thermotherapy mode is currently not clearly defined. Different authors give values within 55-80 °C. Thermotherapy is a minimally invasive method based on the effect of unfocused electromagnetic energy on prostate tissue. In this case, the energy is supplied to the prostate using a transurethral antenna. A thermotherapy session is usually single, lasting 60 minutes.

Transurethral access provides:

• predominant effect on the neck of the urinary bladder and the prostatic part of the urethra, the area of localization of alpha-adrenergic receptors;
• predominant impact on the transitional zone of the prostate, where the main centers of adenoma proliferation are concentrated;
• the best conditions for creating a urine outflow channel (taking into account the small depth of penetration of microwaves).

The mechanism of action of transurethral microwave thermometry is the formation of a necrotic zone in the depth of the prostate tissue while maintaining the prostatic part of the urethra intact. In this regard, almost all microwave thermotherapy devices are equipped with a cooling system. The consequence of temperature exposure is the formation of a necrotic focus in the depth of the prostate. Subsequent replacement of necrotic areas with denser fibrous tissue leads to traction of the walls of the urethra to the periphery, which decreases urethral resistance and IVO. In addition, thermal denaturation of alpha-adrenergic receptors of the bladder neck, prostate and prostatic part of the urethra explains the effect of transurethral microwave thermometry on the dynamic component of obstruction by persistent alpha-adrenergic blockade. The specific effect of microwaves on prostate tissue leads to the formation of a zone of ultrastructural cellular changes around the necrotic focus, in which the antiproliferative effect of thermotherapy is manifested. At the periphery of the heating source, effects characteristic of hyperthermia are observed.

The fundamental point of planning a thermotherapy session in a specific clinical situation is the use of the optimal dose of absorbed energy, which is determined by the ratio of the output power and the cooling mode of the urethra. It should be borne in mind that insufficient cooling can lead to an increase in the number of complications due to thermal injury to the urethra, while too intensive cooling leads to a decrease in the effectiveness of thermal action. The lower the temperature of the cooling liquid, the lower the maximum temperature in the depth of the tissue and, accordingly, the greater the distance from the urethra is the peak of the maximum temperature.

Comparison of urodynamic parameters after transurethral microwave thermometry and TUR shows that surgical treatment has a reliable advantage, but this thermal method has a comparable symptomatic effect. But, taking into account postoperative complications, it can be said that thermal treatment is significantly safer than electroresection.

The following side effects were observed during thermotherapy: bladder spasm (in 70% of patients), minor hematuria (50-70%), dysuria (48%), pain in the urethra or perineum (43%). These symptoms did not require discontinuation of treatment and disappeared on their own after some time. Ejaculation disorders were noted in 8.14% of patients after thermotherapy.

The most common complication of thermotherapy was acute urinary retention, which was observed in almost all patients who underwent high-intensity exposure. The development of acute urinary retention requires drainage of the bladder with a urethral catheter or by trocar cystostomy.

Transurethral radiofrequency thermal destruction

The idea of a hard temperature effect in case of pronounced obstructive manifestations was implemented in the method of transurethral radiofrequency thermal destruction (or thermal ablation) of the prostate (70-82 °C). This method is based on the use of the energy of electromagnetic oscillations of the long-wave radio range. Unlike other types of electromagnetic energy, the penetration of radio radiation is much less dependent on the properties of the environment. This makes it possible to use this method in case of prostate adenoma in combination with pronounced sclerotic changes and calcification of the prostate, i.e. when the use of other types of thermal treatment is limited.

An antenna mounted on the base of a urethral catheter converts the energy of a high-frequency electromagnetic field into heat, which causes tissue destruction as a result of a local increase in temperature to 80 °C and higher. As a result of a single hour-long procedure, an extensive zone of coagulation necrosis is formed around the prostatic section of the urethra in a radius of 10 mm or more. After the rejection of necrotic masses, a cavity is formed in this area in 6-8 weeks, which leads to the elimination of infravesical obstruction. Since the method involves thermal destruction of the prostatic section of the urethra, there is no need to cool it. Only local cooling of the seminal tubercle and striated sphincter is performed. A computer security system does not allow the temperature in the area of the anterior wall of the rectum to rise above the critical level of 42 °C. Considering the large volume of tissue that is subject to destruction, the method can be used in patients with severe infravesical obstruction and with cystostomy drainage to restore spontaneous urination.

Comparison of the results of transurethral radiofrequency thermal destruction and TUR showed that in terms of effectiveness this method cannot compete with surgical treatment, but in some cases they demonstrate comparable results.

The most common complication of transurethral radiofrequency thermal destruction with preserved independent urination is acute urinary retention, which develops in almost all patients. Expressed destructive changes in the area of the prostatic section of the urethra create objective difficulties in inserting a urethral catheter, which requires emergency cystostomy. Given the need for long-term drainage of the bladder (up to 10 days or more), it is advisable to perform the procedure with puncture cystostomy.

Balloon dilation

Balloon dilation is a direction in the treatment of prostate adenoma based on attempts at mechanical dilation of the prostatic section of the urethra, and has a long history. A metal dilator for this purpose was first used by Mercier in 1844. Subsequently, several balloon systems for dilation with different designs were proposed. There is also a combination of balloon dilation of the prostatic section of the urethra with a simultaneous session of water hyperthermia. In this case, a liquid heated to 58-60 °C is fed into the balloon under pressure.

Theoretically, the effect of balloon dilation is mechanical expansion of the urethra, commissurotomy (intersection of the anterior and posterior interlobar commissures), compression of the prostate and an effect on the alpha-adrenergic receptors of the bladder neck and prostatic urethra.

The manipulation is performed under local anesthesia with endourethral gel. The balloon catheter is installed under endoscopic or radiological control. The balloon is expanded under a pressure of 3-4 atm. to approximately 70-90 CH.

Clinical observations demonstrate short-term positive dynamics of subjective and objective indicators in approximately 70% of patients. However, after a year, the effect is preserved in only 25% of patients. The most common complication of the method is macrohematuria. The results of subsequent randomized studies indicated unsatisfactory long-term results of balloon dilation, which is why the 3rd International Conference on Prostate Hyperplasia did not recommend this method for widespread use.

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Urethral stents

Palliative methods of eliminating infravesical obstruction in prostate adenoma include the installation of endourethral stents, which have recently seen an increase in interest. Implantation of urethral stents can be used as an independent method of treating prostate adenoma or as the final stage of various treatment methods when it is necessary to ensure adequate long-term drainage of the bladder. The main arguments in favor of using internal drainage systems are a reduced risk of urinary infection, a reduction in the duration of hospitalization, and rapid social adaptation of the patient. The use of stents is contraindicated in the presence of recurrent urinary infection, bladder stones and neoplasms, neurogenic bladder, urinary incontinence, and dementia.

For intraurethral drainage of the bladder, several devices of various designs have been proposed, which can be divided into temporary and permanent according to the time they remain in the back of the urethra. Temporary stents include intraurethral catheters, urological coils of the first and second generations, as well as self-absorbing stents.

Nissenkorn and Barnes intraurethral catheters are made of polyurethane. They have a fixing socket (like Maleko) at the end and a thread for extraction. Cases of Nissenkorn catheter installation for up to 16 months have been described.

Temporary stents of the first generation include Urospiral, Endospire and Prostacath. This type of stent is a tightly twisted steel spiral with a diameter of 20 to 30 CH, which ends with a bridge and a fixing ring. Stents are produced in several sizes, and Endospire and Prostacath have a gold coating. The main fragment of the spiral is placed in the prostatic, and the fixing ring is in the bulbar section of the urethra so that the transition bridge is in the area of the external sphincter of the bladder. Stents are installed under X-ray or ultrasound control using endoscopic instruments or special guide catheters.

The use of advanced materials, such as titanium-nickel alloys with a memory effect (nitinol), led to the emergence of second-generation urospirals: Memokath and Prostacoil.

The advantage of stents with a memory effect is their ability to change their dimensions under the influence of different temperatures. The Memokath stent is a urospiral with an external diameter of 22 CH and an internal diameter of 18 CH. Before insertion, the stent is cooled and installed in the prostatic section of the urethra under visual control using a flexible cystoscope. When irrigated with a solution heated to 50 °C, the stent expands and is tightly fixed to the wall of the urethra. If necessary, the urethra is irrigated with a cold solution (10 °C), after which the stent can be easily moved to a new position or removed.

The Prostacoil spiral is also made of nitinol and consists of two fragments connected by a bridge. Its diameter in a cooled state is 17 CH, while in a straightened state it reaches 24-30 CH. Stents are produced with a length of 40 to 80 mm. The stent is installed in a cooled state using a special guide catheter under X-ray or ultrasound control. The long fragment of the spiral is installed in the prostatic section, and the short one in the boulevard section of the urethra. This stent is removed using the method described above.

Clinical results indicate high efficiency of temporary stents. According to various authors, symptomatic improvement is observed in 50-95% of patients.

After stent installation, improvement of urodynamic parameters is noted, and Qmax can increase by 2-3 times. A significant decrease in V and a decrease in detrusor pressure are observed according to cystomanometry data.

Complications of internal drainage using temporary stents:

• stent migration;
• urinary infection;
• stent inlay;
• irritative symptoms and stress urinary incontinence;
• urethrorrhagia.

Their frequency depends on the type of stent and drainage time. More complications are noted when using first-generation stents. Clinical experience with Memokath and Prostacoil coils indicates a complication rate of 7-9%, with virtually no cases of stent migration or incrustation.

The production of self-absorbable stents is related to the field of the latest biotechnology, and their clinical application is at the experimental stage. They look like a urospiral, they are made of polyglycolic acid polymers. Stents with different programmed absorption times from 3 to 25 weeks have been developed and tested: PGA 3-4 weeks, PDLLA 2 months, PLLA - 4-6 months. They are planned to be used for internal drainage of the bladder after various endoscopic and thermal procedures (laser ablation, laser or radiofrequency interstitial coagulation of the prostate, transurethral thermotherapy, thermotherapy, focused ultrasound thermoablation, etc.). The first experience of clinical use of self-absorbable stents indicates the achievement of good results with a minimum number of complications.

Permanent stents are intended for lifelong drainage of the bladder and look like an elastic mesh tube made of metal wire. These include: ASI titanium stent. Urolume Wallstent. Ultraflex and Memotherm. After the stent is installed, the mucous membrane of the urethra grows into its mesh structure with subsequent epithelialization after 3-6 months. Due to this, it is almost impossible to remove the stent after a long period of standing.

The ASI stent, made of titanium, is a foldable structure with a diameter of 26 CH, which is placed on the balloon of the urethral catheter before insertion. The stent is installed under X-ray or ultrasound control. After inflating the balloon in the prostatic section of the urethra, it straightens to 33 CH, due to which it is firmly fixed to the urethral wall.

Urolume and Uroflex stents have a similar structure and appearance of a spiral metal mesh. Urolume is produced in lengths from 15 to 40 mm and has a diameter of 42 CH in the straightened state. Stents of this type are installed under endoscopic control using a special tube with an optical channel. inside which the stent is in a compressed state. After selecting a position with a special pusher, the stent is moved into the urethra, where it straightens and is fixed due to its elastic properties. At the same time, if there is an error in positioning, it is almost impossible to move the stent to a new position, which requires its removal.

The Memotherm stent is also a mesh structure, which, however, has a different weave from the previous devices, it is made of nitinol. Initially, it is installed with a similar tool using the method described above. If it is necessary to change the position of the stent, it is irrigated with a cold solution, after which it can be moved or removed. It is possible to re-install the stent in a cooled state using endoscopic forceps. After heating, the stent is straightened and fixed in this position to the urethral wall.

Thus, based on the analysis of existing methods of treating prostate adenoma, it can be said that at the current stage of development of urology, there is no ideal method. The impressive arsenal of means used today poses a difficult task for specialists to choose a method that best suits a specific clinical situation. Determining the indications for a particular type of exposure ultimately comes down to maintaining a balance between the effectiveness and safety level of the treatment method in question. In this case, one of the determining factors is ensuring the necessary quality of life for the patient.