The appearance of kidney stones is a pathological condition that is often complicated by concomitant diseases: pyelonephritis, cystitis, hypertension. If you do not take measures to remove stones from the kidneys, it eventually leads to severe urolithiasis, chronic kidney failure and nephrectomy( kidney removal).
Kidney stones
The reasons for the formation of kidney stones include:
- genetic predisposition;
- disorders of mineral and salt metabolism;
- imbalance of calcium( primary, developing against a background of various pathologies, or secondary, caused by impaired renal function);
- insufficient intake of liquid( water);
- abuse of protein and salty foods.
The most intense pain is caused by small stones with multiple protrusions and thorns, scratching the cavity of the urinary ducts. Large diameters can block the ducts of the tubules, which leads to a deterioration in the excretory capacity of the kidneys and a decrease in the outflow of urine.
Kidney stones should be disposed of. Small in diameter stones( sand) are washed out independently, but if the diameter exceeds 0.5 mm - a crushing is necessary to prevent blockage of the ureter or the urethral canal. Modern urological methods allow you to get rid of kidney stones in a non-invasive way or with minimal surgical intervention.
Kidney stones fragmentation by ultrasound
Shock-wave lithotripsy is considered to be the main method of crushing small stones in the kidneys - an apparatus for affecting small and medium diameter calculi( stones) with the help of ultrasonic waves. The essence of the procedure is the impact on the stones of a directed high-frequency shock wave, which causes their destruction.
Lithotripsy can be performed in the following ways:
- remotely;
- is transurethral( contact);
- is percutaneous( with access through the skin).
Indications
The main indication for the procedure of lithotripsy is the formation of kidney stones.
The method of crushing is selected on the basis of the parameters of the stones:
- Size:
- remote - no more than 20 mm;
- transurethral - no more than 25 mm;
- percutaneously - over 25 mm.
- Density:
- remote - no higher than 1000 HU on the Hounsfield unit scale( otherwise treatment will not be limited to one session);
- is transurethral and percutaneous - it does not matter.
The density of stones depends on the salts and substances that they are formed. The stones are divided into:
- Oxalates are the most common formations with a variety of spines, causing severe pain when passing through the urinary tract. Their density is from 970 to 1518 HU.Often such stones have a branched structure, similar to coral, from where they received the name coral kidney stones. Can fill the entire cavity of the kidney: in this case, the resemblance to the coral is maximal.
- Phosphates and struvite stones - are formed and expand fairly quickly, but relatively soft( from 390 to 969 HU), so they are easily amenable to remote lithotripsy. They have a rounded roughened shape and do not cause severe injuries when leaving in a natural way.
- Urat - very soft stones, the density of which is 202-377 HU.Often they are treated with dissolution with the help of special solutions and only in rare cases ultrasonic crushing is required.
- Stones of mixed salts are relatively rare, but are considered to be the hardest( although they may be soft, depending on the substances and salts they are formed).
There are other types of stones that form in the kidneys, but they are rather soft, do not cause injury or crush.
Coralloid oxalate stones are not subjected to remote crushing due to the branched form. Their destruction can lead to serious complications in the escape of fragments. Transurethral contact lithotripsy can be used to remove parts of coral formation with a vacuum. But the preferred method is percutaneous lithotripsy, laparoscopy or surgical removal of stones with full surgical access.
Procedure
For the crushing of kidney stones, a special device - lithotripter is used. Most modern models are universal, have built-in x-ray guidance, ultrasonic focus and can be used for other procedures. The procedure is carried out without cuts and penetrations: a special pillow filled with a liquid is applied to the projection of the location of the stone, through which a shock wave passes through the generator and points to the concrete. Lithotriptors differ in the mechanism of generation of shock waves.
The procedure for the destruction of stones begins with the impact of shock-wave pulses of minimum power with a large gap, which allows the tissues to adapt. This reduces the risk of hematomas and bleeding. Gradually, the frequency and power of the pulses are increased.
The session is considered effective if it was possible to fragment the stone into particles easily passing through the ureteral and urethral canal. To facilitate removal of remnants of stones, a ureteral stent or a percutaneous nephrostomy can be placed.
- Electro-hydraulic generator. Has the highest efficiency, until 1987 was considered the only method, and now it is used only for 30% of devices. The power is up to 3 million pulses, which makes it possible to correct the strength of the shock wave pulse. It requires frequent preparation of water( 1 time in 3 sessions) and regular replacement of electrodes at the rate of 1 electrode per crushing of 1 stone. Therefore, electrohydraulic generators are considered costly.
- Electromagnetic generators are used on 50% of all manufactured lithotriptors. Focusing can be carried out by a lens or parabolic reflector, the wave beam can not be adjusted. Focusing with the lens is used for larger stones - its focus is 6-12 mm. The focus of the reflector does not exceed 8 mm. Because of this narrow focus, there is no possibility of crushing large kidney stones.
- The piezoelectric generator focuses with a spherical reflector, on the surface of which there are a number of piezo plates generating a shock wave. As a rule, the focus does not exceed 3 mm, therefore devices of this type of wave generation are considered effective at crushing stones up to 1 cm. The quality of crushing of stones from 1.5 cm sharply decreases and the probability of their splitting into large fragments increases, which will lead to repeated repeated sessions.
The second important characteristic of a lithotripter is the working distance - the depth at which the shock wave can reach. The working distance is chosen based on the physique of the patient and the remoteness of the calculus.
Distance of the focal zone( working distance) can be:
- small - 13-14 cm;
- medium - 14.5-15.5 cm;
- large - 160-170 cm.
In Russia, a distance of 14 cm is considered critical, so the use of devices with a lower focal distance is extremely rare.
On video about the types and indications for the procedure of crushing stones in the kidneys with the help of ultrasound:
Extracorporeal lithotripsy
Extracorporeal lithotripsy is often called distance shock wave, since it is carried out non-invasively, without penetrating the patient's body. Abbreviations such as DLT or ESWL are also often used. The procedure is allowed with kidney stones up to 20 mm in diameter and with stones in the ureter up to 15 mm. The outflow of urine should not be hampered.
There are a number of contraindications for remote lithotripsy:
- Critical growth( above 200 cm).
- Overweight( weight over 130 kg).
- Pregnancy.
- Menstruation.
- Acute inflammatory disease, including urinary organs( kidneys, bladder, urethra).
- Blood pathologies, including insufficient clotting.
- Heart pathology.
- Narrowing of the ureter, leading to a violation of the outflow of urine below the calculus.
If the patient takes blood thinning medications, then they must be canceled 7-10 days before the procedure.
Remote crushing of stones is not carried out with:
- density of stones over 1000 HU( sometimes 900 HU);
- large size( more than 20 mm).
This reduces the effectiveness of the procedure and most likely it will take more than one session to completely get rid of the stones.
Before the procedure begins, the following tests are submitted:
- General analysis of urine.
- Clinical and biochemical blood test.
- Determination of the presence of antibodies to HIV.
- Wasserman's reaction is the exclusion of syphilis( RW).
- Coagulogram( coagulability of the blood).
- Detection of HCV( hepatitis C) HBsAg( hepatitis B).
- Determination of blood type and Rh factor.
Before the procedure, a number of standard examinations are assigned:
- ECG.
- US of kidneys, bladder, pelvic organs.
- Radiography of the chest( fluorography).
During the procedure, ultrasound guidance is used, which allows the doctor not to release the calculus from the field of vision and carefully monitor its fragmentation.
The length of stay in a hospital is determined individually. In the case of small stones up to 10-12 mm, the patient can leave the hospital 4-5 hours after the procedure. At stones from 15 mm it is recommended to remain in a hospital for 2-5 days.
Extracorporeal crushing of kidney stones is considered a procedure with minimal trauma, but fragments can injure the internal surface of the ureter, bladder or urethra when exiting.
Therefore, after the procedure, it is observed:
- An admixture of blood in the urine.
- Burning during urination.
- Temperature rise to subfebrile markings( 37-38 ° C).
- Education with bruising and bleeding( rare).
On the video about remote lithotripsy:
Contact
Contact lithotripsy is a method of crushing and removing stones from the kidneys through transurethral access. The procedure is performed under general, less often spinal anesthesia. Trauma is minimal, because the introduction of instruments through the urethral canal is performed.
The main reasons for preferring contact lithotripsy:
- Contraindications for the remote mode.
- Large size of stones.
- High density of formations( over 1000 HU).
- An attack of renal colic with obstruction of ureteral lumen and impairment of urinary outflow.
- With prolonged locating of the calculus in the lumen.
- Multiple concrements.
- Ineffectiveness of 2-3 sessions of remote lithotripsy.
When answering the question of how the fragmentation takes place, it should be said that the method of transurethral lithotripsy is considered more effective, since the physician has direct access, can act on it directly, and the removal of fragments is performed by aspiration( literally - by suction through a vacuum tube).
Before the procedure, a series of general analyzes and studies are performed, similar to extracorporeal lithotripsy.
Reviews
According to urologists, the effectiveness of ultrasonic crushing of kidney stones depends on the validity of the chosen method. With small stones, you can safely apply remote shock wave lithotripsy. But with the size of the stone more than 2 cm, especially with oxalates, it is necessary to conduct contact transurethral crushing. Coralloid concrements of large size are not subject to crushing and are removed surgically.
According to patients, remote fragmentation, conducted without anesthesia, is very painful. It is not always possible to achieve complete elimination in 1 session, so you have to repeat the procedure. The main advantages of the patients are the absence of invasion: no post-invasive period, antibacterial therapy is not always prescribed, and the development of inflammation caused by the instrumental removal of stones is simply impossible. Each remote fragmentation session is quite expensive - about 7,000 rubles.