Patient lying on table under Extracorporeal Shockwave Lithotripsy Machine
Extracorporeal Shockwave Lithotripsy, “ESWL” for short, was developed in the 1980′s. It works by using sound waves to break kidney stones. It is the least invasive stone surgery.
Patients lay on their back on a special operating table. After sedation, an gel apparatus that looks like a giant breast implant (see second photo) is placed against the patient’s back side on the site where the kidney stone is present. Loud and powerful sound waves are then produced by various methods, depending on machine type.
We used to have patients inside a large pool of water, but switched to a more convenient gel-based media to transmit the sound waves.
Targeting of the Stone During Soundwave Lithotripsy
The challenge then is to use the ESWL machine’s X-Rays to identify and target the sound waves onto the stone. On average, 2,000 shock waves are then delivered to the stone and “treatment success” during the operation is noted when a sharply denoted stone at the beginning of treatment on X-Ray is more “fuzzy” or hazy towards the end.
Obviously, the hard part for some patient comes AFTER the treatment, when these fragments have to actually pass.
Thus, our clinical experience and research recommends this treatment to patients with smaller stones (<1cm) so that the fragments after ESWL would be small enough to pass easily.
In those patients who have larger stones or several stones that are targeted with ESWL, we typically recommend placing a stent (a plastic tube resembling a straw) to help prevent the kidney from becoming blocked while the stone fragments are passing down and out.
Placing a stent requires a urologist to look inside the bladder with a cystoscope (camera).
Soundwave Lithotripsy Machine
After treatment is complete, patients are awaken and taken to the recovery area. A couple of hours of observation are typical afterwards. Patients are expected to have pain that is normally eased with tablet pain medications.
This surgery is normally done in the outpatient setting and thus patients are sent home same day unless there are other health problems that require an admission to the hospital.
Typically less than one hour, but may be longer depending on how long it takes to sedate a patient, how well the stone is targeted and whether a stent needs to be placed. Like a lot of things in surgery, the actual treatment is quick, but the setup in the OR, patient positioning, sedation and preparation takes often more time than expected.
ESWL Treatment Head
May be done with moderate sedation General anesthesia (heavy sedation with a ventilator) is recommended for best results. With general anesthesia, we are able to control patient's breathing and thus allow for better targeting of the stone.