What is Modifier 51 in Medical Billing?

Every coder knows that modifiers are the key to correct reimbursements and claim processing. Are you losing a significant amount due to the incorrect reporting of multiple procedures performed within the same session? Modifier 51 might be the solution to your revenue problem. 

This two-digit code is quite important in medical billing. In simple terms, it impacts your reimbursements as it triggers the multiple procedure payment reduction (MPPR) rule. But how does it work, and when should you use it? Let us answer all of these questions with a simple description and detailed examples.

Modifier 51 – Description

Modifier 51 has a pretty simple description. As we mentioned in the beginning, it defines multiple procedures in medical billing. But what exactly do multiple procedures signify in this context? To be more specific, professional coders use this two-digit code to specify that a healthcare provider performed:

• Multiple procedures at the same time.
• A single operation several times on different sites.
• A single procedure, multiple times in the same area.

There are, however, some restrictions to this code. Modifier 51 does not cover evaluation and management (E/M), physical medicine, and rehabilitation services, nor the supplies. Moreover, it only helps you receive complete payment for the primary service. Therefore, you should list all the procedures in the correct order.

When to Use Modifier 51

So, when can you use this code? Modifier 51 is applicable in the following situations:

• When multiple procedures are performed by the same healthcare provider.
• The physician performs them on the same patient and within the same session, but bills them on two separate claims.
• The technical component of multiple diagnostic procedures is subject to the MPPR rule. 

Don’t understand the last point? It simply means that the MPPR rule applies to subsequent imaging or diagnostic procedures. Hence, payers reimburse them at reduced rates.

When Not to Use Modifier 51?

We hope that you now understand when to use modifier 51. But to truly avoid basic mistakes, you must also be aware of the incorrect usage of this two-digit code. Here are some situations in which you should never apply the 51 modifier:

• When two different physicians are involved in the same session.
• Two different providers perform distinct and unrelated surgeries on the same day.
• When filing a claim for a Medicare beneficiary.

Keep one more thing in mind! Avoid using modifier 51 with add-on and E/M codes. As for Medicare, its processing system will automatically add this modifier to the correct procedural code. However, you must submit complete documentation for this.

Modifier 51 – Usage Example

The rules are quite clear, but we get it that you might need some real-world examples to understand this modifier better. So, here is a detailed scenario:

Simultaneous Laparoscopic Cholecystectomy and Appendectomy 

Suppose that a middle-aged man visits his gastroenterologist complaining of intense pain in his right upper abdomen, nausea, and vomiting. Upon a physical examination, the GI specialist discovers that the man also has a fever. The physician sends the patient for an abdominal ultrasound, and the imaging test results reveal gallstones. Due to the restriction in the flow of bile, the patient’s gallbladder became inflamed (cholecystitis). 

Upon further questioning, the physician learns that the patient suffers from chronic cholecystitis. So, as a permanent treatment for gallstones and cholecystitis, the physician suggests a gallbladder removal surgery (CPT code 47562). However, while performing the surgery, the physician notices that the infection has spread to the appendix, and, therefore, proceeds to perform a laparoscopic appendectomy (CPT code 44970). Since the laparoscopic cholecystectomy was the primary procedure, it will be reimbursed in full, and the medical coder will append modifier 51 to CPT 44970 to indicate that a laparoscopic appendectomy was also performed in the same operative session.  

Modifier 51 vs. 59

Many people confuse modifier 51 with 59 because they are both used to report multiple services. However, they are not at all the same. To avoid the same problem, you must learn the following key difference:

Modifier 51 is for reporting multiple procedures, while modifier 59 specifies distinct services performed on the same day.

Multiple Services within the Same Encounter (Modifier 51)

Modifier 51 helps you report multiple procedures performed within the same session. This may include the same operation performed several times or different operations performed within the same session. However, the key difference is that, unlike modifier 59, services reported with modifier 51 are reimbursed at a reduced rate. 

Distinct Services on the Same Day (Modifier 59)

These services are usually not reported together as they are often bundled. Modifier 59, in short, helps you bypass bundling edits by specifying that the services you have performed are distinct. This allows you to receive separate yet complete payments. 

Another key difference is that you don’t have to perform all these services within the same session. You can use modifier 59 on all separately identifiable services performed on the same day.

Final Thoughts

Now you can correctly report multiple procedures with modifier 51. This modifier may seem simple, but payer restrictions and changing requirements make it difficult to use. Many people also confuse it with another similar modifier, modifier 59. That’s why we have discussed it in quite detail so you can confidently tell insurers that multiple procedures were performed during the same encounter.

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