Thanks for your question.
If there are several stones in one kidney, you cannot charge 50590 more than once for that session. The -50 modifier is used only when both kidneys have stones that require ESWL treatment. So, you should bill 50590 with 50 modifier.
The Urology coding alert is an important evidence to justify this. I am attaching the article.
Proper modifier use is key to surviving these kidney stone scenarios
ESWL represented by 50590 (Lithotripsy extracorporeal shock wave) is one of the most frequently performed procedures in urology practices as well as a popular and effective treatment for renal calculus (kidney stones). Our experts give you the facts for seven tricky ESWL coding scenarios.
Scenario 1: Multiple Stones in 1 Kidney
Problem: The urologist performs ESWL to break up multiple stones in the same kidney. Can you bill CPT Codes CPT 50590 for each stone the urologist fragments?
Solution: Sorry - if there are several stones in one kidney you cannot charge 50590 more than once for that session says Carolyn Zell CPC billing manager for the Urology Team in Austin Texas.
Scenario 2: Stones in Right Kidney and Right Ureter
Problem: The urologist finds stones in both the right kidney and the right ureter. Can you bill for ESWL performed on both sites?
Solution: Whether the stones are in the renal pelvis the calyx the ureteropelvic junction the ureter or all four locations use 50590 only once per kidney for each session. The code is valued to cover those occasions when multiple stones are treated as well.
Scenario 3: Stones in Both Kidneys
Problem: Most urologists would treat bilateral stones with ESWL at different times one within the global period of the first. How can they get reimbursed for both procedures?
Solution: Usually when faced with bilateral kidney stones urologists will indicate in the preoperative note that the ESWL will be staged with one kidney initially and another several weeks later. This prospective planning for a staged procedure must be clearly documented in the preoperative note the patient's chart or the operative note of the first procedure.
Append modifier -58 (Staged or related procedure or service by the same physician during the postoperative period) to the second 50590 if done at a different time says Lisa Center CPC quality review coordinator for the Freeman Health Center in Joplin Kan.
Note: When a patient has stones in both kidneys some urologists may treat both with ESWL at the same time although this is ""rare "" Center says. Report 50590 with modifier -50 (Bilateral procedure) in this case.
Remember: Use -LT (Left) and -RT (Right) modifiers to indicate which kidney the ESWL targeted Center says. If the left kidney stone is treated first use 50590-LT; for the second ESWL use 50590-RT-58.