Extracorporeal shock wave lithotripsy (ESWL)

How ESWL works

How ESWL works

Extracorporeal shock wave lithotripsy (ESWL) uses focused sound waves to break kidney / ureter stones into smaller pieces so that they can pass out more easily. It is suitable for stones < 2 cm in size. The success rate depends on the site of the stone and its hardness. The patient lies on a water-filled cushion and the stone is localized by means of X-ray or ultrasound. High-energy sound waves are generated by the machine to shatter the stone.


Dr Chin doing ESWL

Dr Chin doing ESWL

Stone localised on xray

Stone localised on xray


The procedure is very safe and does not damage the kidney or surrounding organs. ESWL is easily done as an outpatient procedure and takes about 1 hour. Analgesic / sedation injection is needed because a few thousand shocks are delivered to break the stone.

Complications include:

  • bloody urine.This occurs for a few days only.
  • colicky pain. As the stone fragments pass out, they cause temporary blockage and pain results. It may take a few weeks for these fragments to completely pass out. Hence, one has to drink plenty of water to help flush out the small stones. A check xray and ultrasound is done 2 to 4 weeks later to confirm the outcome. Should there be any remnant stone > 5 mm, a second session may be needed.
  • swollen kidney (hydronephrosis). If the stone fragments that descend are still too big, they may get stuck along the lower ureter. If severe, a double-J stent may need to be inserted to unblock the kidney.
  • urinary tract infection.This is due to release of bacteria within the stone.
  • kidney haematoma.This is usually small and resolve over a few weeks. Large haematomas cause persistent loin pain and fever and require antibiotics to prevent infection.