Extracorporeal shock wave lithotripsy (ESWL)

Picture of Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy (ESWL) uses focused sound waves to break urinary stones into smaller pieces so that they can pass out easily. It is suitable for stones < 2 cm in size. 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 then generated to shatter the stone. The procedure is very safe and does not damage the kidney or surrounding organs. ESWL is mostly done as an outpatient procedure and takes up to 1 hour. Analgesic injection is given before start of treatment because a few thousand shocks need to be delivered before the stone can be broken. Some patients may require additional sedation. The success rate depends on the site of the stone and its hardness.

Complications include:

  • bloody urine. This occurs up to a few days.
  • colicky pain. As the stone fragments pass out, they cause temporary blockage resulting in pain. It may take a few weeks for all of the fragments to pass out. A check xray and ultrasound is done 2 to 4 weeks later to confirm the outcome. Should there be any remnant stone > 5mm, a second session may be needed.
  • obstructed kidney (hydronephrosis). If the stone fragments that descend are not small enough, they may get stuck along the ureter and cause further swelling of the kidney. If the blockage is severe, secondary procedures like ureteroscopy or double-J stenting may be needed.
  • urinary tract infection. This is due to release of bacteria within the stone.
  • kidney haematoma (blood clot). This is usually small and resolve over a few weeks. Large haematomas cause persistent loin pain and fever and require antibiotics to prevent infection of the blood clot.