Extracorporeal Shock Wave Lithotripsy

Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-invasive medical procedure that uses high-energy sound waves, called shock waves, to break kidney stones into smaller pieces. These smaller fragments can then pass more easily out of the body through the urine. It is a common treatment option for certain types and sizes of kidney and ureteral stones.

What is Extracorporeal Shock Wave Lithotripsy?

Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-surgical procedure that treats kidney and upper ureteral stones by using focused shock waves generated outside the body. These high-energy waves travel through the skin and tissue to target and shatter the stones into tiny fragments, which can then be passed naturally in the urine.

The term "extracorporeal" means outside the body, highlighting that the treatment does not require an incision. During ESWL, a specialized machine creates high-energy sound waves, known as shock waves. These waves are precisely aimed at the kidney stone using imaging guidance, such as X-rays or ultrasound. When the shock waves hit the stone, they create tiny cracks, gradually breaking it into smaller pieces. The goal is to reduce the stone to fragments small enough to pass out of the body through the urinary tract. ESWL is often considered for stones that are too large to pass on their own but are not causing severe complications that require immediate surgical removal.

Why it's done

ESWL is primarily performed to treat kidney stones and sometimes ureteral stones that are causing symptoms or complications. These can include severe pain, blood in the urine, urinary tract infections, or a blockage that prevents urine flow and could potentially damage the kidney.

Kidney stones can cause intense pain, often described as colicky pain, which can radiate from the back or side to the abdomen and groin. Other symptoms may include nausea, vomiting, and frequent, painful urination. When stones are too large to pass naturally, or if they are causing persistent symptoms or complications, treatment becomes necessary. ESWL is typically recommended for stones that are less than 2 centimeters in diameter, especially those located in the kidney or upper ureter. It is a less invasive alternative to surgical procedures for suitable stones. Your doctor will assess the size, location, and composition of your stone to determine if ESWL is the most appropriate treatment option for you.

How to prepare

Preparing for ESWL involves several steps to ensure your safety and the procedure's effectiveness. You will typically need to discuss your medical history and all medications with your doctor, stop taking certain blood-thinning drugs, fast for several hours before the procedure, and arrange for someone to drive you home afterward.

Before your ESWL procedure, your doctor will review your medical history, including any allergies, previous surgeries, and current health conditions. It is crucial to inform them about all medications you are taking, including over-the-counter drugs, supplements, and herbal remedies. Blood-thinning medications, such as aspirin, ibuprofen (Advil, Motrin IB), naproxen sodium (Aleve), warfarin (Coumadin), and clopidogrel (Plavix), usually need to be stopped several days to a week or more before ESWL. Your doctor will provide specific instructions on when to stop these medications. You will also be instructed not to eat or drink anything for several hours before the procedure, typically after midnight the night before. Arranging for a ride home is essential because you will likely receive sedation or anesthesia, which makes it unsafe to drive yourself.

What happens during

During an ESWL procedure, you will lie on a special table, often receiving sedation or general anesthesia to ensure comfort. The medical team uses imaging techniques, such as X-ray or ultrasound, to precisely locate the kidney stone. A machine then delivers focused shock waves through your skin to break the stone into smaller fragments.

Once you are positioned on the treatment table, usually on your back or side, you will receive medication to help you relax or sleep. This could be conscious sedation, which makes you drowsy but awake, or general anesthesia, which puts you completely to sleep. Your vital signs, such as heart rate, blood pressure, and oxygen levels, will be continuously monitored. To ensure the shock waves are accurately directed, a gel is applied to your skin over the kidney area. The doctor then uses X-ray (fluoroscopy) or ultrasound imaging to pinpoint the exact location of the stone. The ESWL machine then delivers a series of high-energy shock waves, typically between 2,000 and 3,000 pulses, through the skin to the stone. The procedure usually lasts about 45 to 60 minutes.

Recovery & timeline

After ESWL, you can typically go home the same day, usually within a few hours of the procedure. Recovery involves drinking plenty of fluids to help flush out the stone fragments, managing mild to moderate pain with medication, and watching for any signs of complications. Passing the stone fragments can take days to several weeks.

Immediately after the procedure, you will be monitored in a recovery area until the effects of sedation or anesthesia wear off. It is common to experience some discomfort or bruising on your back or side where the shock waves were applied. You may also notice blood in your urine for a few days, which is normal as the body begins to pass the stone fragments. Drinking a large amount of water is crucial during recovery to help move the stone fragments through your urinary tract. You might experience pain or discomfort as these fragments pass, which can be managed with over-the-counter pain relievers or prescription medication from your doctor. Most people can resume light activities within a day or two, but strenuous exercise should be avoided for a short period. A follow-up appointment, often with an X-ray or ultrasound, is usually scheduled a few weeks later to check if the stone fragments have cleared.

Risks & side effects

While ESWL is generally considered safe, potential risks and side effects can occur. Common side effects include temporary blood in the urine, bruising at the treatment site, and pain as stone fragments pass. Less common but more serious risks include infection, incomplete stone removal, or, rarely, kidney damage or a blockage from stone fragments.

The most common side effects after ESWL are temporary blood in the urine (hematuria) and bruising or tenderness on the skin where the shock waves were delivered. Many people also experience pain or discomfort as the stone fragments pass through the urinary tract, which can sometimes be severe. Less common risks include a urinary tract infection, which can sometimes lead to a more serious kidney infection. In some cases, the stone fragments may not pass easily and can form a "stone street," a blockage in the ureter that may require additional procedures. Rarely, ESWL can cause temporary kidney dysfunction, or, in very rare instances, bleeding around the kidney (perirenal hematoma) or long-term high blood pressure (hypertension). It is important to contact your doctor if you develop a fever, severe pain, or difficulty urinating after the procedure.

Success rate

The success rate of ESWL, defined as being stone-free or having only small, clinically insignificant fragments, varies significantly based on factors such as the stone's size, location, and composition. While generally effective for smaller kidney stones, many people achieve stone-free status after one or more treatments, with rates often ranging from 50% to 90%.

For stones smaller than 2 centimeters, especially those in the upper part of the kidney, ESWL typically has a good success rate. However, larger stones, stones in certain locations (like the lower pole of the kidney), or very hard stones (such as cystine stones) may be more challenging to break and pass, leading to lower success rates. Many studies report stone-free rates for ESWL ranging from about 50% to 90%, depending on the specific characteristics of the stone and the patient. It is important to understand that "success" often means the stone has been broken into pieces small enough to pass, rather than immediate complete clearance. Some individuals may require more than one ESWL treatment, or a different procedure, if the initial treatment is not fully effective. Your doctor will discuss the expected success rate based on your specific situation.

Frequently asked questions

Can ESWL treat all types of kidney stones?

No, ESWL is not suitable for all kidney stones. Its effectiveness depends on the stone's size, location, and composition. It works best for smaller stones (less than 2 cm) in the kidney or upper ureter. Very hard stones or those in difficult-to-reach locations may require alternative treatments. Your doctor will determine if ESWL is appropriate for your specific stone.

Is ESWL painful?

During the ESWL procedure, you will typically receive sedation or general anesthesia, so you should not feel pain. Afterward, it is common to experience mild to moderate pain or discomfort as the stone fragments pass through your urinary tract. This pain can usually be managed with prescribed or over-the-counter pain relievers.

How long does it take to pass all stone fragments after ESWL?

The time it takes to pass all stone fragments after ESWL varies widely among individuals. Some people may pass fragments within a few days, while for others, it can take several weeks. Drinking plenty of fluids is crucial to help facilitate the passage of these fragments through your urinary system.

Will I need more than one ESWL treatment?

It is possible to need more than one ESWL treatment. The need for repeat procedures depends on how well the stone breaks up during the first session and if all fragments pass successfully. Your doctor will monitor your progress with follow-up imaging and discuss if additional treatments are necessary.

What are the alternatives to ESWL for kidney stones?

Alternatives to ESWL include ureteroscopy, where a thin scope is passed through the urethra and bladder to remove or laser the stone, and percutaneous nephrolithotomy (PCNL), a more invasive surgical procedure for very large or complex stones. For very small stones, watchful waiting may also be an option.

Can ESWL prevent future kidney stones?

No, ESWL treats existing kidney stones but does not prevent new ones from forming. To reduce the risk of future stones, your doctor may recommend lifestyle changes, such as increasing fluid intake, dietary modifications, or medications, based on the type of stone you had and its underlying cause.

Sources

• MedlinePlus — Extracorporeal Shock Wave Lithotripsy
• Mayo Clinic — Extracorporeal Shock Wave Lithotripsy
• Cochrane Library — Extracorporeal Shock Wave Lithotripsy