50590

Lithotripsy, extracorporeal shock wave

Extracorporeal Shock Wave Lithotripsy (ESWL) is a non-invasive therapeutic procedure primarily utilized for the fragmentation of urinary calculi located in the kidney or the upper ureter. The procedure employs a device called a lithotripter, which generates high-energy acoustic pulses (shock waves) outside the body. These shock waves are focused precisely on the stone using real-time imaging, such as fluoroscopy or ultrasound. As the energy waves encounter the dense structure of the stone, the resulting mechanical stress and cavitation cause the stone to break into smaller, sand-like particles. These fragments are then small enough to be excreted naturally through the urinary tract during voiding. The procedure is typically performed in an outpatient setting under general anesthesia or heavy intravenous sedation to ensure the patient remains immobile, allowing for consistent targeting of the stone. A water-filled cushion or a water bath is used to couple the shock wave generator to the patient's skin, facilitating the transmission of energy with minimal trauma to the intervening soft tissues. ESWL is most effective for stones that are between 5 mm and 20 mm in diameter and are composed of materials that respond well to fragmentation, such as calcium oxalate dihydrate. Following the procedure, patients are monitored for successful fragment passage and potential complications like hematuria or 'steinstrasse' (stone street), where fragments temporarily block the ureter.

Clinical Indications

  • Symptomatic renal calculi (kidney stones)
  • Upper ureteral calculi typically located above the pelvic brim
  • Calculi usually ranging from 5 mm to 20 mm in diameter
  • Patient preference for a non-invasive treatment over endoscopic or surgical intervention
  • Failure of conservative management for spontaneous stone passage
  • Obstructive uropathy caused by a stone amenable to shock wave fragmentation

Procedure Steps

  1. Patient is positioned supine or prone on the lithotripter table based on stone location.
  2. Induction of general anesthesia or monitored anesthesia care (MAC) to prevent movement.
  3. Initial localization of the urinary calculus using fluoroscopic X-ray or ultrasound guidance.
  4. Application of a coupling medium (gel) and positioning of the water-filled bellows against the flank.
  5. Fine-tuning of the shock wave focal point to ensure it aligns with the stone's center.
  6. Initiation of shock wave delivery, starting at lower energy levels and gradually increasing based on stone response and patient tolerance.
  7. Delivery of approximately 2,000 to 3,000 shock waves per session while continuously monitoring stone fragmentation via imaging.
  8. Periodic adjustment of the focal point if the stone shifts or fragments.
  9. Assessment of stone disintegration at the conclusion of the shock wave delivery.
  10. Recovery and post-procedural monitoring for pain management and hydration.

Coding Guidelines

  • CPT 50590 is a unilateral code. If performed on both kidneys during the same session, modifier -50 (Bilateral Procedure) should be applied.
  • The use of fluoroscopy or ultrasound for intraprocedural stone localization is considered bundled into 50590 and is not reported separately.
  • If a cystourethroscopy with ureteral stent placement (52332) is performed during the same session to facilitate fragment passage, it is separately reportable with modifier -51.
  • The global period for 50590 is typically 90 days. Repeat ESWL sessions within this period may require modifier -76 (Repeat procedure by same physician) or -58 (Staged procedure).
  • Do not report 50590 in conjunction with other lithotripsy codes like 52353 (laser lithotripsy) for the same stone.
  • If the procedure is performed at an Ambulatory Surgery Center (ASC), facility coding rules apply.

Associated ICD-10 Codes