Extracorporeal shock wave lithotripsy (ESWL)

Picture of Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shock wave lithotripsy (ESWL) is the used of focused sound waves to break urinary stone 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 then generated by the machine 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 about 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.

Complications include:

  • bloody urine. This can occur for up to a few days.
  • colicky pain. As the stone fragments pass out, they cause temporary blockage and pain results. As it may take a few weeks for these fragments to completely pass out, drink plenty to flush out these stone fragments. 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.
  • swollen kidney (hydronephrosis). If the stone fragments that subsequently descend are too big, they may get stuck along the ureter. If severe, a ureteroscope or a double-J stent may need to be inserted.
  • 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 this haematoma.