Kidney Stone Fragmentation with Sound Waves (ESWL) in Turkey

Kidney stone fragmentation with sound waves (ESWL) is an effective treatment method that does not require a surgical incision and enables stones in the kidney and urinary tract to be broken into pieces with high-energy shock waves applied from outside the body. The stones are broken into small pieces and naturally passed through the urine.

In response to the question of how the ESWL treatment method is applied, during the procedure the location of the patient’s stone is determined with imaging techniques and focused sound waves are sent to the targeted area. These waves create pressure on the stone and cause it to break, and the need for anesthesia is generally minimal.

The recovery process after the kidney stone fragmentation procedure varies depending on the patient’s stone size and general health condition. Mild pain and blood in the urine may be seen during the passage of the fragmented stones, but this is mostly temporary and improves in a short time.

Within the scope of who ESWL is applied to and what its risks are, this method is generally suitable for kidney stones of certain sizes and is not preferred in the presence of pregnancy, bleeding disorders, or infection. Appropriate patient selection increases treatment success and reduces the risk of complications.

What Is ESWL and What Is Its Historical Development?

Kidney stone disease is a health problem as old as human history. In past years, the treatment of kidney stones was quite difficult. Patients underwent open surgeries with large surgical incisions, had to stay in the hospital for weeks, and it took months for them to return to normal life. The infection risks, incisional hernias, and serious bleeding caused by open surgeries were among the greatest disadvantages of the period. However, medical technology is in constant progress. In the early nineteen-eighties, a physical principle accidentally discovered during aviation and space research in Germany created almost a revolution in the world of medicine. The power of the shock waves created by raindrops hitting the bodies of aircraft was noticed, and this principle was adapted to the human body.

Thus, the first ESWL devices emerged. At first, patients were placed inside large water-filled tubs. The waves passed through the water and reached the kidney. Over time, these devices underwent an incredible evolution. The tubs disappeared, the devices became smaller, and they turned into much more focused, comfortable table systems. Today, patients can come to the hospital in their daily clothes and walk home after a one-hour procedure. The absence of a surgical incision, the minimal need for anesthesia, and the almost nonexistent risk of infection have made this method one of the most valuable and indispensable inventions of modern medicine.

Why Do Kidney Stones Form and Which Factors Are Effective?

Kidney stones form when certain minerals and salts in the urine crystallize and come together. Under normal conditions, there are protective substances in urine that prevent this crystallization. However, sometimes this balance is disrupted. The concentration of substances such as calcium, oxalate, and uric acid in the urine increases and exceeds the capacity that the fluid can dissolve. In this case, these substances begin to form sediment. Over time, these small sediments combine and turn into grains of sand and then into the hard stone forms we know.

The main factors that disrupt this balance and accelerate stone formation are as follows:

• Insufficient water consumption
• Excessively salty diet
• Genetic predisposition
• Sedentary lifestyle
• Obesity

Low water consumption causes the urine to become concentrated and its color to darken. Concentrated urine is a perfect environment for stone formation. Genetic factors are also extremely important. Individuals with a family history of kidney stones are much more likely to encounter this disease at some point in their lives. In addition, the sedentary lifestyle and fast-food-heavy, salty diets of the modern age put excessive strain on the kidneys. Especially in summer, not replacing the water lost through sweating causes urology clinics to fill with people suffering from kidney pain.

How Do ESWL Devices Produce Shock Waves?

Although ESWL devices appear complex from the outside, their basic working principles are quite clear. The aim is to focus a powerful energy produced outside the body on a stone located deep within the body with millimetric precision. Different technologies have been developed over the years to produce this energy. According to their method of generation, the devices are basically divided into three groups.

The first technology is electrohydraulic systems. In these systems, there are two electrodes inside a water-filled chamber within the device. A very high electric current is suddenly delivered between these electrodes. This spark formed in water causes the water to suddenly vaporize and emit a very powerful shock wave, like a tiny explosion. The resulting wave is collected by a special reflective dish and directed directly toward the stone.

The second and much more widely used system today is electromagnetic generators. Here, the working principle can be compared to a giant loudspeaker. A metal membrane is suddenly vibrated using a powerful magnetic field. This sudden vibration pushes the water and produces very regular and stable shock waves. The greatest advantage of electromagnetic devices is that the waves can be focused much more sharply on the stone and the lifespan of the device is longer.

The third system is piezoelectric technology. These devices contain thousands of tiny crystals. When electricity is applied to these crystals, they all expand and contract simultaneously. This synchronized movement creates tiny pressure waves in the water. The greatest characteristic of these waves is that the point at which they reach the target, that is, the focal point, is extremely small. In this way, the waves do not spread to surrounding tissues while passing through the skin, and the pain felt by the patient is kept at the lowest level.

How Do Shock Waves Break the Stone Without Damaging the Body?

To understand this issue, it is necessary to look at how sound and energy travel through different environments. A large part of the human body consists of water and soft tissues. When shock waves pass through water or soft tissues, they encounter no resistance. Just as a sound wave in the sea can travel problem-free for kilometers, the waves entering the body also pass gently through muscles, fat, and organs without harming them. However, when the wave strikes a hard object, that is, a kidney stone, the physical aspect of the matter changes completely.

The two main physical mechanisms that occur during stone fragmentation are as follows:

• Pressure-dependent fragmentation
• Cavitation effect

Pressure-dependent fragmentation occurs at the moment the wave first hits the stone. The shock wave strikes the front surface of the stone like a very hard slap. This impact creates a severe vibration in the crystal structure of the stone. As the wave passes through the stone and exits its back surface, it meets the urine fluid surrounding the stone. The energy reflected back from the fluid this time pulls the stone from the inside outward. As a result of these opposite forces, small pieces begin to break off from the back of the stone.

The cavitation effect is a fascinating event that occurs at the microscopic level. As shock waves pass through the liquid, they create microscopic air bubbles. These bubbles suddenly expand under the effect of the wave and then collapse violently inward in a fraction of a second. These millions of microscopic explosions occurring right on the surface of the stone erode the surface of the stone, just as rough waves gradually carve out rocks. When these two mechanisms are repeated continuously, that hard kidney stone turns into very fine sand within minutes.

Who Are Suitable Candidates for ESWL Treatment?

Not every kidney stone case is the same, and not every treatment method suits everyone. Although ESWL is a very comfortable method, its success depends greatly on choosing the right patient. The patient’s kidney structure, weight, general health condition, and the characteristics of the stone must be examined meticulously. If this evaluation is not done correctly, the patient may be put through a process from which they will not benefit.

The characteristics that suitable candidates who will benefit most from the treatment should have are as follows:

• Stone size smaller than twenty millimeters
• Normal kidney anatomy
• Ideal body mass index
• No bleeding disorder
• No pregnancy

Shock waves generally provide excellent results for stones smaller than twenty millimeters, that is, below two centimeters. If the stone is larger than this, even if it is broken, the risk of the enormous amount of sand and gravel produced blocking the urinary tract becomes much higher. Therefore, in large stones, directing the patient directly to closed surgery is a safer strategy. In pregnant women, this procedure is absolutely not applied because the effects of sound waves on the baby in the womb cannot be predicted. Likewise, ESWL is not preferred in people who use blood thinners and cannot stop these medications because of the risk of bleeding inside the kidney.

How Does the Location of the Stone in the Kidney Affect the Success of ESWL?

The kidney is a complex organ containing different chambers and a wide central cavity. These chambers are called calyces, and the central cavity is called the pelvis. The urine produced by the kidney first collects in these chambers, flows into the pelvis, and finally travels downward to the bladder through the thin channel we call the ureter. Where the stone is located in which chamber of the kidney or in which part of the pelvis is one of the most critical factors determining the passage rate after fragmentation.

If the stone is located in the middle cavity (pelvis) of the kidney or in the upper chambers, this is quite advantageous anatomically. Because the outlets of these chambers look directly downward toward the opening of the canal. After the stone is broken by shock waves, it can easily pass into the urinary canal, almost like sliding down a slide with the help of gravity. The success of fragmentation and passage is always much higher in upper and middle stones.

However, if the stone is located in the lower chambers of the kidney (lower calyx), the physical conditions become a little more difficult. The lower chamber resembles a blind pocket located at the very bottom of the kidney. In order for the fragmented particles to exit this pocket and reach the urinary canal, they need to move uphill. This struggle against gravity is quite difficult. If this lower pocket in the patient’s kidney is anatomically very narrow or its angle is steep, even if the stone is completely fragmented, it may remain accumulated in that pocket. Therefore, the situation is evaluated in detail in lower pole stones. In stones in the urinary canal, it is decided whether focusing can be done by looking at whether the stone corresponds to bony structures.

What Is the Relationship Between the Hardness of the Stone and ESWL Success?

It is not possible to understand how hard a patient’s stone is by looking from the outside only with ultrasound or a normal X-ray. This is where advanced radiological imaging techniques come into play. The computed tomography (CT) performed before the procedure not only shows the location and size of the stone, but also maps its density and hardness. On tomography, the hardness of the stone is measured with a unit called the “Hounsfield Unit,” abbreviated as HU.

Stones whose HU value measured on tomography is below one thousand are relatively soft and fragile stones that easily lose resistance against shock waves. ESWL sessions applied to these stones usually result in a short time and with high success. However, when the HU value rises to one thousand two hundred, one thousand three hundred, or above, the physical resistance increases greatly. These stones, which have contents such as calcium oxalate monohydrate or cystine, have a structure almost as hard as concrete. When shock waves hit these stones, they cannot transfer their energy inside and are reflected back from the surface, just like a rubber ball bouncing off a wall. Trying to break such hard stones with sound waves usually results in failure, and in these cases, it is recommended to directly use laser fragmentation methods.

What Preparations Are Made Before the ESWL Procedure?

After the method is decided, there are some simple but very important preparations that need to be made until the day of the procedure. First of all, the patient’s general health condition is reviewed. Kidney functions and the presence of any urinary tract infection are checked with a simple blood and urine test. If an active infection is detected in the urine, it is necessary to first eliminate the infection with antibiotic treatment, because when the stone is broken, trapped bacteria may enter the bloodstream.

In addition, the medications regularly used by the patient are carefully questioned. Some drug groups that need to be stopped or adjusted under doctor supervision before the procedure are as follows:

• Blood thinners
• Aspirin derivatives
• Rheumatism medications

Since shock waves create a minimal vibration in the kidney tissue, these medications, which delay blood clotting, may cause unwanted minor bleeding around the kidney during or after the procedure. Therefore, blood thinners may need to be discontinued a few days before the procedure or switched to injectable forms. There is no harm in the patient having a light breakfast on the morning of the procedure, but it is important to avoid foods that cause excessive gas. Because dense gas accumulation in the intestines can act as an invisible wall that prevents sound waves from reaching the stone.

What Awaits the Patient During the ESWL Session?

When you enter the procedure room, you are greeted by a technological table and a fragmentation head integrated into it. There is no need to completely remove your clothes; it is enough that only your waist or back area where the fragmentation procedure will be performed remains exposed. After you lie down on the table, the technician or the relevant specialist determines the location of the stone millimetrically with the help of ultrasound or fluoroscopy (X-ray) devices. Once the target is determined, the head of the device is placed against your skin with a special fluid similar to ultrasound gel applied in between. This gel allows the sound waves to pass directly into your body without dispersing in the air.

When the procedure starts, the first thing you will hear is a rhythmic and solid “click click” sound. Each sound represents a shock wave sent into your body. The device is deliberately started at a very low energy level at first. The purpose of this is to give the kidney vessels time to constrict and allow the kidney to gradually adapt to this vibration. After a few minutes, the energy and shot rate are gradually increased. In an average session, between two thousand and three thousand shock waves are sent to the stone depending on its size. It is very important for the patient to remain as still as possible during this process and to breathe calmly. Irregular or very deep breaths cause the kidney to move up and down and the stone to shift away from the target. The procedure is usually completed within thirty to fifty minutes.

Is the ESWL Procedure Painful and Is Anesthesia Required?

This is one of the most frequently wondered questions and the issue that makes patients the most anxious before the procedure. Since a strong acoustic energy is sent from the outside into the body, the procedure is not completely without sensation. When the shock waves hit the skin, a sensation like repeated elastic impacts may be felt, and deep in the kidney a dull pressure may be perceived. However, this is definitely not in the form of a knife cut or unbearable pain.

In today’s modern ESWL applications, a wide variety of options are offered to ensure the comfort of the patient. In the vast majority of adult patients, a strong painkiller injection administered about half an hour before the procedure through the hip or vein is sufficient to get through the process comfortably. If the patient is extremely anxious or has a very low pain threshold, a mild drowsy state (sedation) can be created with relaxing medications. Full general anesthesia, that is, completely putting the patient to sleep, is very rare in adults; it is generally preferred in children in order to completely eliminate fear and movement.

What Should Be Done for the Stones to Pass After ESWL?

Getting up from the ESWL device and going home shows only that the first stage of the treatment is over. The second and in fact the most important stage that will determine the success of the treatment is the process of washing out and passing those broken sands and small fragments through the urinary tract. The only driving force that will clear these residues inside the kidney is the volume of fluid you consume. After the procedure, movement begins in the urinary tract, and complete clearance of the stones may take several weeks.

The steps that need to be followed to accelerate this passage process and prevent blockage of the canals are as follows:

• Drinking plenty of water
• Walking
• Jumping rope
• Using the prescribed medications

Drinking at least two and a half to three liters of water per day ensures that the fragments are rapidly carried downward without becoming stagnant in the kidney. The light yellow color of your urine is the clearest sign that you are drinking enough water. Just drinking water and lying down is not enough; it is necessary to benefit from gravity. Brisk walks or light jumping movements at home incredibly accelerate the descent of the stones in the canal. In addition, some medications that widen the thin urinary canal called the ureter and relax its contractions may also be prescribed so that the fragments fall into the bladder much more painlessly.

What Are the Possible Side Effects of ESWL Treatment?

As with every medical intervention, fragmentation with sound waves also has some expected and temporary side effects. These are generally the body’s natural responses to mechanical vibration. Knowing how the process works prevents panic. The most common situation is that the color of the urine becomes pinkish or reddish during the first few days after the procedure. This is a normal bleeding caused by mild irritation in the inner lining of the urinary tract during the fragmentation of the stone and returns to normal quickly as fluid is consumed.

Other temporary side effects that may frequently be encountered after the procedure are as follows:

• Bleeding in the urine
• Bruising on the skin
• Mild lower back pain
• Nausea

Mild redness and, in some patients, bruising may be seen in the back or waist area where the shock waves contact the skin. These bruises disappear spontaneously within a few days, just like bruises that occur when you hit somewhere. As stone fragments begin to fall into the canal, dull pain radiating to the back may occur; this condition can be easily controlled with the prescribed painkillers. In very rare situations, large broken fragments may line up one after another and completely block the urinary canal. If this condition, called “stone street,” causes severe pain, a small closed intervention may be required to open that path.

Which Closed Surgical Methods Can Be Used Instead of ESWL?

If the size of your stone exceeds the limits of ESWL, if its location is not suitable for sound waves to reach, or if analyses show that your stone is very hard, fragmentation sessions are not stubbornly continued. Other closed surgical options offered by technology come into play. These methods are modern techniques based on entering directly into the kidney and fragmenting the stone under direct vision. The two most commonly used main methods are RIRS and PNL.

RIRS (Flexible Ureteroscopy) is a scarless procedure performed entirely by entering through the natural openings of the urinary tract. With a very thin flexible instrument that has a camera at its tip and can bend in every direction, it is possible to advance through the urinary canal to the chambers of the kidney. The stones are clearly seen on the screen and are turned into dust within seconds with a thin laser wire sent through the instrument. The patient is usually discharged on the same day or the next morning. It is a highly successful alternative that is not affected by the hardness of the stone.

PNL (Percutaneous Nephrolithotomy) is a method generally applied for giant stones larger than two or two and a half centimeters. Only a small hole of about one centimeter is opened from the patient’s back toward the kidney. Through the tube sent through this hole, the kidney is entered with optical devices. The large stones inside are fragmented with mechanical or pneumatic lithotripters and removed one by one through the same hole. In patients with a very large stone burden, providing complete clearance in a single session with PNL instead of struggling with ESWL for months is the gold standard of modern urology.

Is ESWL Safe in Children?

Kidney stone disease in children is an issue that causes great concern for families and requires very meticulous work to protect kidney health. The biggest question mark in families’ minds is whether these powerful shock waves harm the developing kidney of a tiny child. Very long-term clinical follow-ups and studies have clearly proven that ESWL is extremely safe in children, even in babies a few months old. The waves do not prevent the growth of kidney tissue or leave permanent damage.

Interestingly, child anatomy is more advantageous for this treatment compared to adults. Children’s tissues are much more elastic. Since their urinary canals (ureters) are much shorter than those of adults, the broken stone fragments fall down the canal and into the bladder incredibly easily and quickly. The only point that needs attention is anesthesia. Since it is not possible for children to lie still during the procedure, the procedures are definitely performed under mild general anesthesia (sleeping) and under the control of anesthesiologists in order not to lose the target.