Pathology/Lab Coding Alert

CDC and AHA guidance clarify reporting.

When your lab faces test requisitions for patients with suspected COVID-19-related multisystem inflammatory syndrome in children or adults (MIS-C or MIS-A), it pays to know the latest guidance for correctly coding the cases.

Let our experts usher you through the most recent testing and reporting guidance offered by the Centers for Disease Control and Prevention (CDC) and the American Hospital Association (AHA) ICD-10-CM Coding Clinic.

Focus Diagnosis Coding

If you scrambled during 2020 to accurately report diagnoses for COVID-19 and other conditions related to infection with SARS-CoV-2, you can now look to 2021 ICD-10-CM codes and guidance.

The guidelines are certainly helpful, but accidental misinterpretation may lead you to sequence codes incorrectly — or choose the wrong diagnosis code entirely. Unsurprisingly, “the major changes to the guidelines for FY 2021 involve the addition of rules with regard to COVID-19,” says Melanie Witt, RN, CPC, an independent coding expert based in Guadalupita, New Mexico.

Check out new code: As of Jan.1, you have the following new code available to report MIS-C or MIS-A related to a SARS-CoV-2 infection: M35.81 (Multisystem inflammatory syndrome).

Although the ordering clinician will assign the diagnosis code for any lab tests ordered, you should be familiar with codes and sequencing issues that could interfere with claims payment.

For instance: For lab tests ordered relating to a COVID-19 and MIS-C diagnosis, the code selection and sequencing varies depending on whether the child has an active or past SARS-CoV-2 infection. For an active COVID-19 case, the appropriate coding is U07.1 (COVID-19), followed by M35.81 when the clinician makes that diagnosis. On the other hand, for “MIS-C due to previous COVID-19,” the correct coding is M35.81 with a secondary diagnosis of B94.8 (Sequelae of other specified infectious and parasitic diseases).

Watch documentation: Knowing the correct coding for the preceding scenario depends on the clinician’s documentation, and you should never make assumptions. Although your coding experience may imply the likely clinical sequela, all that matters is the documentation present to support a particular code, according to Elaine Dunn, DHA, RRT, RPSGT, CPCO, vice president of revenue integrity and centralized coding with Change Healthcare in Alpharetta, Georgia.

There’s more: The sequelae code is appropriate in this case because the clinician is actively treating the MIS-C, so you should not use Z86.16 (Personal history of COVID-19) as the secondary code. Nor should you use Z20.822 (Contact with and (suspected) exposure to COVID-19) as the secondary diagnosis in this case because the child has a confirmed past COVID-19 diagnosis.

Finally: If the clinician documents any associated complications, you should see an additional diagnosis code in the medical record for the complication, such as N17.- (Acute kidney failure).

Coder tip: You might see pediatric cases of MIS listed in the documentation as MIS-C or pediatric inflammatory multisystem syndrome (PIMS).

Look for These Lab Tests

The CDC has provided guidance on MIS-C, including a definition of the condition and a list of laboratory testing that clinicians might order for evaluating the condition, including the following:

• SARS-CoV-2 detection by RT-PCR or antigen testing. For instance, labs might perform tests such as 87635 (Infectious agent detection by nucleic acid (DNA or RNA); severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]), amplified probe technique) or 87426 (Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], fluorescence immunoassay [FIA], immunochemiluminometric assay [IMCA]) qualitative or semiquantitative; severe acute respiratory syndrome coronavirus (eg, SARS-CoV, SARS-CoV-2 [COVID-19]))
• SARS-CoV-2 serologic testing, such as 86769 (Antibody; severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19]))
• Testing to detect evidence of inflammation, such as 86140 (C-reactive protein) and 82728 (Ferritin)

For MIS-C cases that include cardiac involvement, labs may also see orders for the following:

• Cardiac enzymes such as 84484 (Troponin, quantitative) cardiac enzyme or troponin testing (per the center’s testing standards) and 82550 (Creatine kinase (CK), (CPK); total)
• Heart failure indicators such as brain natriuretic peptide (BNP) or N-terminal proBNP (NT proBNP), which report to 83880 (Natriuretic peptide)

Resource: For CDC guidance on MIS-C, see www.cdc.gov/mis-c/hcp/.