Extracorporeal shock wave lithotripsy (ESWL) is a form of treatment for people suffering from kidney stones. It uses sound waves to break up stones in the urinary tract, after which they are passed in the urine due to the particles' greatly decreased size. Generally it is a very safe procedure without the need for general anesthesia, but like all medical interventions, has a risk of side effects.
Pain is a common side effect of the procedure and is usually a result of the stone fragments passing. The discomfort is common due to the fact that the urethra is a sensitive structure that was not meant to push stones through, but the level of discomfort is not as high as it would be if the stone was passing at its original pre-lithotripsy size.
Hematuria (Blood in the urine)
Blood in the urine is a common side effect. It will occur as the stone particles are passed in the urine. If the bleeding persists, it could possibly point to retained stone fragments, which may not have been broken down to sufficiently small sizes for passage in urine. Sometimes this occurs and repeat procedures will be necessary.
Infection can be a complication of ESWL due to the fact that many of the stones can harbor bacteria. In fact, bacteria can cause stone formation by altering the pH of urine. Breaking up the stones can cause release of bacteria and their toxins. This is why antibiotics are commonly given before the procedure.
Through various mechanisms like free radical production and bubble formation (which is actually how the stone is broken into pieces), lithotripsy can damage the kidney. The most common side effects that can be seen right after lithotripsy are bleeding and edema (swelling) in or around the kidney. This can result in long-term decrease in renal function.
Erosions in the stomach and duodenum have been reported with ESWL, and the damage has a similar mechanism as renal damage. Damage to the pancreas has also been identified, with increase in amylase levels (enzyme secreted by pancreas, especially when injured) seen even when clinical evidence of pancreatitis is absent.
Initially, lithotripsy has been observed to cause constriction of the blood vessels to the kidney resulting in increased blood pressure and a decrease of blood flow to the kidney. Studies that followed showed that over the long term, ESWL patients had a measurable increase in diastolic blood pressure. Thus patients with existing hypertension and those at risk for future hypertension should be counseled before undergoing treatment.
The recurrence of stones is higher after lithotripsy than after other medical interventions. This seems to be the case because of residual stone debris that is not cleared. These act as foci around which future stones can form.