Modifiers for multiple stones raise questions


We have never seen so many changes in coding and billing for any service that would equal the changes we’ve seen for reporting multiple stones in the urinary system. Over the past 3 years, we’ve witnessed multiple opinions and differing payment results.

We have never seen so many changes in coding and billing for any service that would equal the changes we’ve seen for reporting multiple stones in the urinary system. Over the past 3 years, we’ve witnessed multiple opinions and differing payment results.

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You might recall that we first published an article based on Medicare’s rules allowing for the reporting of treatment of separate lesions (“How to bill for stones in the same kidney”). Based on Medicare’s ruling and our understanding of the intent of this ruling, our article stated that you could bill separately for the treatment of multiple stones using the principle that a stone was no different than a lesion in work effort when in fact the stone was non-contiguous and diagnosed prior to treatment.

The AUA then received a letter from Niles R. Rosen, MD, head of the National Correct Coding Initiative, stating that it was not permissible to bill for multiple stones at any location on the same side in the urinary system, based on the fact that stones were not lesions. The AUA appealed that decision.

Last August, Medicare, in an effort to further reduce an identified abuse of modifier –59, introduced a new series of modifiers –X (E, S, P, U) to be used in place of modifier –59 in Medicare. The “X” modifiers were implemented on Jan. 1, 2015 and provide a new set of definitions for separate procedures. These new definitions provide a fresh look at multiple procedure allowance.

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The reason Dr. Rosen cited for not billing for multiple stones has now been changed and may again allow billing for multiple stones when extra work effort is provided and supported by documentation. Unfortunately, Medicare has not published detailed instructions on how to use the modifiers. Therefore, the correct use of at least two of the modifiers could be interpreted in several ways. We anticipate that Medicare will publish additional regulations and/or details on their recommended use in the near future.

NEXT: AUA weighs in on modifier use

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AUA weighs in on modifier use

In the meantime, the AUA has published, in the Feb. 17 AUA Policy & Advocacy Brief, its recommendations for billing Medicare and private payers for procedures to remove multiple stones using “X” modifiers and the –59 modifiers.

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We recommend that you read the brief closely and follow these recommendations from the AUA’s Coding and Reimbursement Committee (CRC) and use the modifiers as detailed in the brief. If you have further questions after reviewing this article and the AUA brief, feel free to email questions to The AUA has no rulemaking authority. However, we can assume that payers will adopt some or all of their recommendations.

In general, with one possible exception, the AUA is recommending that you not charge for multiple stones in a single kidney, or multiple stones in a single ureter. In addition, the association has stated that one cannot report the same procedure if performed for two stones in the same structure. You can, however, bill for multiple stones if they are in different structures (defined by the AUA as a kidney, a ureter, or the bladder).

Our take on the recommendations

We work closely with the AUA on issues related to coding and reimbursement and rarely disagree with the organization on coding interpretations such as these. This is one of those rare incidences that we hope they are wrong on two issues. Why draw the line at providing the same procedure for two separate stones in two separate areas of the kidney or ureter, and why was structure limited to big structures instead of smaller structures?

To be more specific, why is each calyx not a different structure? Is the parenchyma a different structure from the renal pelvis? Why is separate operative technique mentioned as a defining factor in use of modifiers? Can separate work effort be documented and charged if the same procedure code is provided on more than one diagnosed stone on the same side?

Our concerns are twofold: one for patients and the other for our colleagues who have developed the expertise to remove the complete stone burden from a kidney laden with multiple stones. We have seen the statistics showing that this method of treating multiple stones prevents a higher percentage of recurrent stones.

If the urologist is not paid for the extra work, and the facility is not paid for the extra time, equipment, and supplies required to treat the stone in the calyces as well as a stone obstructing the ureteropelvic junction, then the urologist may be encouraged or required to take out the symptomatic stone and leave behind the stones in the calyces.

For the patient, this could mean multiple recurrent calculi and recurrent trips to the OR that could have been prevented. If the facility is willing to absorb the extra cost, we have already seen that many urologists will absorb the extra time and effort to relieve the full stone burden without extra pay in order to provide the highest quality care.

We have always interpreted the basic premise of the resource-based relative value scale (RBRVS)-based payment system to allow extra payment for extra work based on the CPT surgical package. This belief is based on two key principles:

  • Relative value units are based on vignettes indicating average work provided in a defined circumstance. (Supplies are also based on these basic vignettes in the form of ambulatory payment classfications or Practice Expense Values in an outpatient setting.)

  • Physicians work in an elaborate system of global periods, modifiers, and associated rules addressing circumstances defining included services, services that are excluded, and circumstances in which billing for additional services are allowed.

In the case of stones and stone treatment, we believe the RBRVS payment is based on the work for removal of a single stone, and the new modifiers and the associated definitions provided by Medicare seem to indicate an intent to meet the needs related to increased work effort and time provided in treating multiple stones.

NEXT: –59 modifier, "X" modifiers


The Medicare fee-for-service model is primarily based on the premise that services that are medically necessary and reasonable should be paid in a manner that is commensurate with the codes reported and are inclusive of the average services and work effort required according to the CPT description. Payer payment rules and bundling edits were developed to prevent double payment for any service.

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The –59 modifier was created to allow a provider to report unusual circumstances that required extra work at the same encounter that were normally considered to be included in the services provided. The definition gave us flexibility but was designed to allow us to receive payment for services “not ordinarily encountered or performed on the same day by the same individual,” to quote a key part of the definition. Medicare has restated the same concept, and its definition of the XU modifier “does not overlap usual components of the main service.”

According to CMS, the four “X” modifiers were establish to define specific subsets of the –59 modifier. (Modifier –59, according to the current Medicare guidelines, can still be used.) The four new modifiers are defined as follows:

  • XE Separate Encounter, A Service That Is Distinct Because It Occurred During A Separate Encounter

  • XS Separate Structure, A Service That Is Distinct Because It Was Performed On A Separate Organ/Structure

  • XP Separate Practitioner, A Service That Is Distinct Because It Was Performed By A Different Practitioner

  • XU Unusual Non-Overlapping Service, The Use Of A Service That Is Distinct Because It Does Not Overlap Usual Components Of The Main Service.

The correct use of these modifiers in billing for multiple stones will depend on the interpretation of “separate structure” and “unusual non-overlapping service,” the perceived potential for abuse, and payer instructions on how they plan to pay.

NEXT: Examples of 'X' modifier use


Examples of ‘X’ modifier use

Here are some examples of how you should code for multiple stones based on AUA recommendations:

Example 1. Ureterscopy with lithotripsy of a stone in the ureter and a stone in the kidney. Indwelling ureteral stent is inserted.

• 52356

• 52353-XS for Medicare (–59 for private)

As these are two separate stones in two separate structures

Example 2. Ureterscopy with lithotripsy of a stone in the upper calyx and a stone in the pelvis. Indwelling ureteral stent is inserted.

• 52356

As these are two separate stones in the same structure

Example 3. Ureterscopy with lithotripsy of a stone in the upper ureter and a stone in the lower ureter. No indwelling ureteral stent is inserted.

• 52353

As these are two separate stones in the same structure.

One of the issues that we see not directly defined by Medicare is a scenario in which two separately diagnosed stones in the same structure are treated with different operative techniques. The question we have is, could this be addressed with the use of modifier –XU?  Note: Based on the definition of procedural global, we do not think that treating the same stone with multiple techniques during the same operative session should be reported with more than one CPT code. The new modifiers do not change this opinion. 

Based on our interpretation of the AUA article, treatment of separate stones in the same structure with the same operative technique would not be allowed to be reported; again, we ask, could this be addressed with –XU? We await final interpretation for Medicare on this issue as well.

NEXT: "One problem that has to be addressed"


Unfortunately, one problem that has to be addressed is that some of our colleagues are willing to “push the envelope” and bill for stones that require little or no extra work. Our job as consultants is to provide you with the correct way to report using the best logic we can to interpret the rules provided by CPT and the payers. Payers set up the rules to prevent payment to anyone trying to abuse the system.

We are in hopes that CMS will publish interpretations/regulations that will allow for extra pay for medically necessary extra work and at the same time prevent payment for fraudulent or medically unnecessary services.


We will have to wait for the final answer until Medicare clarifies its use of the “X” modifiers and the private payers make it clear as to how they intend to pay for multiple stones. In the meantime, we recommend you follow the AUA’s recommendations.

Any time you disagree with an AUA recommendation, you can always write a letter detailing the reason for disagreement and a suggested solution. All letters are given consideration by the CRC.

Stay tuned! We hope to have a better and more definitive answer for you in the near future, and we’ll post it upon receipt.

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The information in this column is designed to be authoritative, and every effort has been made to ensure its accuracy at the time it was written. However, readers are encouraged to check with their individual carrier or private payers for updates and to confirm that this information conforms to their specific rules.

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