Extracorporeal shock wave lithotripsy (ESWL)

Picture of Extracorporeal shock wave lithotripsy (ESWL)

Extracorporeal shockwave lithotripsy (ESWL) uses focused sound waves to break kidney 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. 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. Narcotic analgesic is injected before start of treatment because a few thousand shocks are needed before the stone can be broken. Some patients may require additional sedation.

Complications include:

  • bloody urine. This clears in a few days.
  • colicky pain. As the stone pieces pass out, they can sometimes cause temporary blockage and pain. It may take a few weeks for all the fragments to pass out completely. A check xray and ultrasound is done 2 to 4 weeks later to confirm that all the stones pieces have passed out. Should there be any remnant stone > 5mm, a second session may be needed.
  • swollen kidney (hydronephrosis). If the broken stone pieces are still too big, they may get stuck along the ureter. If severe, a ureteroscope can be passed up to break the large stone pieces or a double-J stent inserted to unblock the kidney.
  • urinary tract infection. This is due to release of bacteria within the stone.
  • kidney haematoma (blood clot). This is usually small and resolves in a few weeks. Large haematomas cause persistent loin pain and fever and require antibiotics to prevent infection.

Desired outcomes:

  • tolerable pain during treatment
  • complete stone breakage ( > 90% success rate)
  • haematoma rate < 3%