Look Over the ABCs of Coding for ASCs

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Curious what it’s like to be an ambulatory surgery center coder? Though ASC coding has many similarities to provider and hospital coding, it’s just a little different from what you’d do for a physician or a facility.

Ambulatory Surgery Centers Defined

In Medicare’s eyes, ASCs are distinct entities operating only to furnish outpatient surgical services — this means that ASCs can’t offer office visits, laboratory services, or diagnostic tests like CT and MRI scans. The Medicare Place of Service Codeset defines ASCs succinctly: “A freestanding facility, other than a physician’s office, where surgical and diagnostic services are provided on an ambulatory basis.” (ASCs use Place of Service Code 24 on the Medicare claim form.)

How ASC Coding and Billing Is Different From Inpatient

Like physician offices, ASCs use CPT® and HCPCS Level II codes to bill most of their services. Unlike inpatient hospital settings, ASCs do not use ICD-10-PCS to report procedures.

Medicare pays for ASC services under Part B and requires the CMS-1500 claim form. Hospital-based ASCs generally use the UB-04 form for facility charges and the CMS-1500 form to report professional charges for the physician’s services. But if you’re reporting services at an ASC, definitely check payer guidance to make sure you know which the payer prefers.

Check Out Medicare’s List of Approved ASC Procedures

Medicare doesn’t permit surgeons to perform just any procedure in an ASC. CMS publishes a list of approved ASC procedures (available here.) Basically, the rule of thumb is that procedures performed in an ASC can’t be emergent or life threatening, like a heart transplant or a re-plantation of a severed arm. Also, CMS forbids ASCs from hosting procedures involving major blood vessels — so certainly no CABGs will be performed in your local surgery center. On the other hand, the procedures must also be the type that would be unsafe to perform in a physician’s office.

Master Some Special ASC Modifiers

What happens if your provider must cancel a surgery scheduled to take place in an ASC? The reason for terminating the procedure would be some extenuating circumstance threatening the physical well-being of the patient, such as unexpected changes in the patient’s blood pressure, sudden chest pain, or some other circumstance that the provider believes puts the patient’s life at risk. Meet two CPT® modifiers specific to ASCs for reporting these situations.

  • Modifier 73, Discontinued Out-Patient Hospital/Ambulatory Surgery Center (ASC) Procedure Prior to the Administration of Anesthesia

You’ll use this modifier to tell the payer that the provider terminated the surgical procedure — one that required anesthesia to perform — before the anesthesia was administered. The provider would have terminated the procedure after the patient was prepped for the procedure and taken to the operating room. When you report modifier 73, Medicare contractors apply a 50 percent payment reduction to the procedure.

  • Modifier 74, Discontinued Out-Patient Hospital/Ambulatory Surgery Center (ASC) Procedure After Administration of Anesthesia

You’ll apply this modifier to a discontinued outpatient procedure terminated by the provider after administering anesthesia. Again, the procedure would have been cancelled by the provider because of a sudden, unexpected change in the patient’s condition, such as blood pressure variants, sudden chest pain, or similar serious conditions. Once anesthesia is administered, the procedure is classified as a surgical procedure, and many payers will reimburse the full amount for the cancelled procedure with modifier 74 appended.

Watch out! Don’t use modifier 73 or 74 for elective cancellation of a service or procedure — these are only for medical reasons discovered after surgical preparation. In other words, to be able to report modifier 73 or 74, the patient must be on the table, prepped and draped in the usual sterile fashion with the surgeon ready to cut, when something happens to the patient that causes the team to stop the procedure in its tracks.

What About You?

Are you an ambulatory surgery center specialist? I bet you have a lot more tips for us, and we’d love to hear them! Please share your comments in the box below.

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Susan taught health information and healthcare documentation at the community college level for more than 20 years. She has a special love for medical language and terminology. She is passionate about ensuring accurate patient healthcare documentation through education. She has a master's degree in healthcare administration, is a certified healthcare documentation specialist, and serves as immediate past president for the Association for Healthcare Documentation Integrity (AHDI).

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