Radiology Coding Alert

Know what situations call for use of modifier 50 versus LT/RT.

An ongoing debate within the radiology coding specialty has to do with the use of modifier 50 (Bilateral Procedure) versus the LT (Left side of body) and RT (Right side of body) modifiers.

Despite the fact that Medicare offers a conclusive set of rules on bilateral billing, a general misunderstanding still remains on what scenarios entail the use of modifier 50 versus modifiers LT/RT.

Consider this expert advice when making a determination on bilateral coding.

Medicare Makes the Rules on Bilateral Billing

There are specific instructions on the use of modifier 50 versus anatomical left and right modifiers in the Medicare Claims Processing Manual, Chapter 4, Section 20.8, explains Jennifer M. Connell, CPC, CENTC, CPCO, CPMA, CPPM, CPC-P, CPB, CPC-I, Owner of E2E Health Solutions in Victoria, Texas. “In short, you use modifier 50 when billing out for services a physician performs on both sides of the body. You do not use the RT/LT modifiers when modifier 50 would apply. However, you may use the RT/LT modifiers when the procedure is detailed as unilateral in the code description,” Connell relays.

Most practices will generally find themselves guilty of incorrectly billing out with modifiers LT/RT instead of modifier 50. Their justification usually hinges on one of two reasons:

1. Some practices mistakenly believe that billing out for two separate procedures with their respective unilateral modifiers will yield higher reimbursement than that of a single bilateral modifier. Since both options are reimbursable at the same level, these practices would be sending out erroneous claims for no reason.

2. Some practices might be basing their choice on a single payer’s prior decision to deny a procedure billed out with modifier 50. Obviously, restructuring your coding guidelines to act in accordance with a single, non-Medicare payer is never advised.

Keep in mind: Unlike a 150 percent reimbursement rate for surgical procedures with modifier 50 and/or LT/RT, CMS reimburses radiological procedures with modifier 50 at 200 percent of the billed code.

Remember: Every Payer’s Different, But Basically the Same

Most payers don’t tend to stray too far outside of the Medicare guidelines when it comes to policies on modifier use. While each payer might articulate their rules differently, the end result still ties back to Medicare’s rules surrounding the application of modifier 50. Those rules are as follows:

“Modifier 50 applies to a bilateral procedure performed on both sides of the body during the same operative session. When a procedure is identified by the terminology as bilateral or unilateral, the 50 modifier is not reported.”

In other words, if a CPT^® code’s description labels it as inherently bilateral or unilateral, do not use modifier 50. Instead, you will opt for an LT/RT modifier for the unilateral procedures and no modifier for the bilateral procedures.

Don’t Let Bilateral Indictors Confuse You

Medicare offers a list of bilateral surgery indicators to use as a reference for when and when not to append modifier 50. While Medicare labels these indicators as surgery-related, they are also applicable to diagnostic imaging procedures. If you’re ever unsure of whether or not the diagnostic procedure you are coding allows for use of modifier 50, you can check for CMS bilateral surgery indicator 3, which exclusively relates to diagnostic radiology:

“Radiological Procedures valid for bilateral criteria. These are radiology/diagnostic tests that are not subject to the special payment rules for other bilateral surgeries, and payment for each is based on 100% of the fee schedule amount.”

If you’re ever unsure of whether you should bill a diagnostic code with modifier 50, you can check the specific code’s bilateral indicator status. “As for where you can find the bilateral status indicators, you can see these in CMS’s Relative Value File, which is updated every quarter,” Connell says. “In the CMS Relative Value File, a corresponding code’s bilateral status indicator can be found in the ‘Bilateral Surg’ column,” she adds.

Example: The physician performs a complete X-ray of the right and left wrist with a diagnosis of “wrist trauma.”

A quick look at 73110 (Radiologic examination, wrist; complete, minimum of 3 views) reveals no mention of laterality in the code description. Further, you will find a bilateral surgery indicator of 3 if you look up 73110 in the CMS physician fee schedule spreadsheet.

In this example, you will bill out one unit of 73110 with modifier 50.

Example: The physician performs a right and a left rib X-ray with posteroanterior views of the chest, three views.

There are not many instances in which you’d be applying an LT/RT modifier to two of the same unilateral radiological procedures. That’s because most unilateral procedures will have an accompanying bilateral code you can opt for instead. Even the code specified in this example has a bilateral code to help counter the use of billing out separately with an LT/RT modifier. Consider the following codes:

• 71101, Radiologic examination, ribs, unilateral; including posteroanterior chest, minimum of 3 views
• 71111, Radiologic examination, ribs, bilateral; including posteroanterior chest, minimum of 4 views

It’s clear when comparing these two codes that the bilateral code 71111 is not applicable. Since 71111 requires a minimum of four views, the only option is to code both unilateral procedures separately (71101-RT and 71101-LT).

Besides this confounding example, you will want to get in the habit of applying modifier 50 to most bilateral diagnostic procedures that don’t include a bilateral code. Despite the fact that the reimbursement is the same if you choose to use the RT/LT modifiers instead, you would still be going against CMS guidelines, potentially increasing the likelihood of an audit in the future.