Extracorporeal Shock Wave Lithotripsy (ESWL)

Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-surgical procedure that uses focused sound waves, generated outside the body, to break kidney stones or other urinary tract stones into small fragments that can then pass out naturally in the urine.

A machine called a lithotripter sits beside or beneath the patient and directs thousands of precisely aimed shock waves at the stone. The repeated impact cracks the stone from the inside out, turning it into sand-like particles. These tiny pieces travel down the ureter (the tube connecting the kidney to the bladder) and are flushed out when the patient urinates, usually over the days and weeks after treatment.

ESWL is most commonly used to treat stones in the kidney or upper ureter (the upper part of the tube between the kidney and bladder) that are causing pain, blockage, or recurrent infections. It works best on stones that are not too large and are made of a type of mineral that shock waves can crack.

• Kidney stones (nephrolithiasis) that have not passed on their own
• Stones in the upper ureter causing pain or obstruction
• Stones causing repeated urinary tract infections
• Stones that are blocking urine flow and threatening kidney function
• Stones detected incidentally that are considered likely to cause future problems

ESWL is not suitable for every patient or every stone. Your urologist (kidney and urinary tract specialist) will assess whether another approach is needed. Situations where ESWL is usually avoided include:

• Pregnancy, because shock waves may harm the developing baby
• Uncontrolled bleeding disorders or patients on blood thinners that cannot be paused
• Very large stones or stones that are very hard (such as cystine or brushite stones), which shock waves often cannot break effectively
• Stones located in the lower ureter, where other techniques often work better
• Severe narrowing or blockage below the stone that would prevent fragments from passing
• Active urinary tract infection that has not yet been treated
• A cardiac pacemaker, in some situations — the team will assess this individually
• Severe obesity, which may prevent the shock waves from reaching the stone

ESWL is generally considered a low-risk procedure compared with open surgery, but it does carry recognised complications that patients should understand before agreeing to treatment.

• Pain or discomfort in the back or side during and after treatment, as shock waves pass through tissue
• Blood in the urine (haematuria) for a few days after the procedure — this is common and usually resolves on its own
• Passage of stone fragments, which can cause temporary pain or a sensation of gravel passing through the urinary tract
• Incomplete stone break-up, meaning a second session or a different procedure may be needed
• Steinstrasse (literally 'stone street') — a chain of stone fragments that builds up in the ureter and partially or fully blocks urine flow, sometimes requiring further treatment
• Urinary tract infection, which may need antibiotics
• Bruising of the skin or underlying tissue near the treatment area
• Rare: injury to the kidney tissue, including bruising of the kidney (renal contusion) or, very rarely, internal bleeding around the kidney
• Rare: the procedure does not work at all if the stone is too hard or too large

Good preparation helps the procedure go smoothly and reduces the chance of complications. Your medical team will give you specific instructions; the points below describe what is typically expected.

Before the procedure, patients are usually asked to fast (have nothing to eat or drink) for several hours, as some form of sedation (medication to help you relax or sleep lightly) or anaesthesia (medication to prevent pain) is commonly used. Blood thinners and certain other medications are often paused for a number of days beforehand — the doctor will advise on this based on your current medicines. Smoking and alcohol are best avoided in the days leading up to the procedure because both can slow recovery.

Several tests are usually carried out before ESWL to confirm the size, location, and composition of the stone, and to make sure the patient is fit for the procedure. These commonly include:

• Imaging: an X-ray (KUB — kidney, ureter, bladder), ultrasound (USG), or CT scan to map the stone precisely
• Urine test to check for infection, which must be treated before ESWL goes ahead
• Blood tests to check kidney function and clotting ability
• Sometimes an EKG (electrocardiogram, a heart tracing) if there are cardiac concerns

On the day of the procedure, the steps generally follow this order:

• 1. The patient changes into a hospital gown and an intravenous (IV) line is placed in the arm to give fluids and medication.
• 2. Sedation or anaesthesia is administered so that the patient is comfortable and feels little or no discomfort from the shock waves.
• 3. The patient lies on a treatment table. Depending on the machine used, the area over the stone may be placed against a water-filled cushion or the patient may be partially submerged in a water bath — water conducts the shock waves efficiently.
• 4. The team uses real-time X-ray (fluoroscopy) or ultrasound imaging to locate the stone precisely and aim the shock waves at it.
• 5. The lithotripter delivers several thousand shock waves over the course of the session. The number of waves and the duration vary depending on the stone and the equipment used.
• 6. Imaging may be repeated during the session to check how well the stone is breaking up.
• 7. Once the session is complete, the IV line is removed and the patient is moved to a recovery area.

Most patients are monitored in a recovery area for a few hours after ESWL and, in many cases, are able to go home the same day. The recovery period at home is usually shorter than after surgical stone removal, but there are important steps to follow to help the stone fragments pass and to watch for complications.

• Hydration: drinking generous amounts of water in the days and weeks after the procedure helps flush the stone fragments out through the urine — the team will advise on how much is appropriate for you.
• Urine straining: patients are often asked to urinate through a fine filter or strainer to catch stone fragments, which may then be sent for laboratory analysis to identify the stone type.
• Pain management: some discomfort in the back, side, or groin is normal as fragments pass; the medical team will recommend suitable pain relief.
• Blood in the urine: a pinkish or reddish colour in the urine is common for a few days and is not usually a cause for alarm, but persistent or heavy bleeding should be reported to the doctor.
• Activity: most patients can return to light daily activities within a day or two, but strenuous exercise and heavy lifting are usually restricted for a short period — the doctor will advise.
• Follow-up imaging: a repeat X-ray, USG, or CT scan is usually scheduled within a few weeks to check whether the stone fragments have cleared and whether the procedure was successful.
• Watch for signs of infection or obstruction: fever, chills, severe pain, or inability to urinate should be reported to a doctor promptly, as these may signal a blocked ureter or infection.
• Dietary and lifestyle advice: the urologist may recommend changes to diet, fluid intake, or specific supplements to reduce the chance of new stones forming in the future.