What is Modifier RT in Medical Billing?

We’ve all been there: staring at a claim rejection for a knee injection or an X-ray that you know was performed correctly. The culprit? Often, it’s a lack of specificity regarding which part of the body the procedure was performed on. This happens when you don’t know how to use the laterality modifiers (like modifier RT) correctly. 

Learning how to use this modifier is vital if you want to get your claims reimbursed. That’s why we have created this detailed guide on what modifier RT is and how to use it in your claims. So, let’s start. 

Modifier RT – Description

The Centers for Medicare & Medicaid Services (CMS) defines modifier RT simply as:

“Right side”.

Like all other modifiers, RT is also a two-character code appended to a Current Procedural Terminology (CPT) or Healthcare Common Procedure Coding System (HCPCS) code. When you append modifier RT to a code, you are stating that a procedure was performed on the Right Side of the body.

Without it, a payer might look at a claim for a “knee X-ray” and wonder if you imaged the left knee, the right knee, or if you’re trying to bill for the same knee twice. The RT modifier clears up this ambiguity.

However, the important point to note here is that RT is specifically for paired body parts, i.e., structures that exist on both the left and right sides of the body, such as:

• Eyes (e.g., cataract surgery)
• Ears (e.g., cerumen removal)
• Extremities (arms, legs, hands, feet)
• Joints (knees, hips, shoulders, elbows)
• Kidneys, lungs

In short, by using RT, you provide the necessary laterality that tells the insurance payer exactly which distinct body part was treated, distinguishing it from the left side (modifier LT) or a bilateral service (modifier 50).

Additionally, modifier RT is an informational modifier. Meaning it only provides information or context about a procedure and does not affect the reimbursement amount. 

Appropriate Use Cases for Modifier RT

Let’s move away from theory and look at some real-world scenarios in which the RT modifier can be used:

Orthopedic Injections

Suppose a patient comes to an orthopedic clinic. The patient has osteoarthritis in both knees. The patient shares that he has tried pain medications, but they didn’t help. After thoroughly assessing the condition, the physician decides to inject the right knee with a corticosteroid today but plans to treat the left knee next week to monitor the patient’s reaction.

So, in this case, the billing department can use CPT code 20610 to bill for the injection and append modifier RT to it to indicate that the procedure was performed on the right knee. 

Diagnostic Radiology

Suppose a patient falls and injures his right wrist and right elbow. Both the wrist and the elbow get swollen. Upon checking, the physician suspects a fracture in both joints. However, to confirm the diagnosis, the physician orders an X-ray examination of both. 

In this scenario, the billing department would bill the appropriate X-ray code for the wrist (e.g., 73100) and the elbow code (e.g., 73070) with modifier RT. 

Accurate Usage Guidelines for Modifier RT

Using RT seems straightforward. However, even small mistakes can lead to claim denials. That’s why following the guidelines and best practices is vital. Here are some points to consider while using the RT modifier:

Do Not Use RT for Bilateral Procedures (Usually)

This is a common error. If a physician treats both ears, do not bill two lines (one with RT, one with LT) unless the payer specifically requires it (some private payers do). 

Standard Medicare guidelines state you should use modifier 50 (Bilateral Procedure) on a single line with one unit of service. Using RT and LT separately when modifier 50 is applicable often results in incorrect payment (paying 100% for the first and 0% for the second), rather than the 150% usually allowed for bilateral.

Match Diagnosis Codes (ICD-10)

If you use RT on the CPT code, your ICD-10 diagnosis code must also specify “right.” For instance, don’t bill CPT 73560-RT (right knee X-ray) with ICD-10 M17.12 (Unilateral primary osteoarthritis, left knee). This mismatch is an automatic denial trigger for most clearinghouses.

Meet Documentation Requirements

Your medical records must support modifier RT’s usage. The operative report or clinical notes must clearly state “right side.” It is not enough to infer it. If the header says “Procedure: Knee injection” but the body of the text doesn’t specify “right knee,” an auditor could technically flag the use of RT as unsupported.

Final Thoughts 

It is time to wrap up this guide. We discussed what modifier RT is and how you can use it effectively in your claims. Here are the highlights:

• The RT modifier indicates that a procedure or service is performed on the right side.
• For RT to be valid, the body parts must be paired, like eyes, kidneys, lungs, etc. 
• RT is an informational modifier and does not affect the reimbursement. 

Medical billing is a complex process, and most in-house billing teams fail to achieve the level of efficiency that is required to meet industry standards. That’s why it is better to get professional medical billing and coding services from third-party companies like NeuraBill. 

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