PROCEDURE

Most patients are positioned supine on the lithotripter bed; however, those with stones in anteriorly located kidneys, medial portions of a horseshoe kidney, or transplanted kidneys should be positioned prone to reduce the skin-to-stone distance and remove skeletal structures from the shock wave path. Once the patient is positioned, the stones are localized using fluoroscopy and, in some cases, ultrasound.

During lithotripsy, the body must be coupled with the shock wave source. This process eliminates the transition between ambient air and the patient’s skin, which would otherwise attenuate the shock wave and cause complications such as ecchymoses and skin breakdown. Because soft tissue has an acoustical impedance similar to that of water, coupling can be achieved either by submerging the patient in a water bath, as in earlier systems, or by applying a water cushion with a silicone membrane directly to the patient’s skin.

The number of shock waves applied to the stones will impact the degree of fragmentation. Each manufacturer determines a machine-specific dosage that should not be exceeded.

POSTOPERATIVE CARE AND COMPLICATIONS

After lithotripsy, patients are encouraged to ambulate and to increase fluid intake to promote stone passage. Postprocedural gross hematuria is common and transient. A mild to moderate degree of abdominal or flank pain is also common; however, severe and persistent pain suggests complications such as hematoma or impaction of stone fragments, which should prompt evaluation with CT scan.

In the absence of a more acute indication, follow-up is typically performed at 2 weeks and includes repeat imaging to assess the success of stone fragmentation and passage. If necessary, residual stones may be treated with a repeat ESWL procedure or other techniques.