Beware of Unspecified CC/MCC "Laterality" Codes

HIM and coding professionals may remember way back on April 1, 2022, that CMS implemented Edit 20 – Unspecified Code Edit for those CC/MCC codes in which there can be further specification of the anatomic site. Here is the quote from that CMS decision:

“After consideration of the public comments received, we are finalizing the implementation of a new code edit for “unspecified” codes, where there are other codes available in that code subcategory that further specify the anatomic site. As noted previously, the severity level of the unspecified diagnosis codes is unaffected and therefore this edit does not affect the payment the provider is eligible to receive.”

“CR 12471 adds new Edit 20 (Unspecified Code Edit) to the MCE. This new edit applies when a code is entered that is:

  • Either a Complication or Comorbidity (CC), or Major Complication or Comorbidity (MCC) AND
  • Includes other codes in that code subcategory that further specify the anatomic site

“We are finalizing the new edit for FY 2022, effective with discharges on and after April 1, 2022.” We are finalizing a new “Unspecified Code Edit: to read as follows:

20. Unspecified Code Edit: Unspecified codes exist in the ICD-10-CM classification for circumstances when documentation in the medical record does not provide the level of detail needed to support reporting a more specific code. However, in the inpatient setting, there should generally be very limited and rare circumstances for which the laterality (right, left, bilateral) of a condition is unable to be documented and reported.

The list of codes subject to this edit are identified in Table 6P.3a associated with this final rule. (Link to tables below in References)

What Does This Mean for the Coder?

There are around 3,500 unspecified codes in ICD-10-CM but not all involve laterality and are CC/MCC. Laterality is what the edit focuses on. In essence, when a coder is assigning a CC/MCC code that has specific codes for right, left or bilateral, the coder should make every effort to identify the laterality and assign that code. If it is not there, the coder should query for laterality. If they do not, usually the encoder or billing software will flag it. However, in some cases the unspecified codes get by and goes out on the claim. The Medicare claim with unspecified laterality code will be returned as follows:

“When a code from the list displayed in Table 6P.3a (Link to it below) is entered on the claim, the edit will be triggered. It is the provider’s responsibility to determine if a more specific code from that subcategory is available in the medical record documentation by a clinical provider. If, upon review, additional information to identify the laterality from the available medical record documentation by any other clinical provider is unable to be obtained or there is documentation in the record that the physician is clinically unable to determine the laterality because of the nature of the disease/condition, then the provider must enter that information into the remarks section. Specifically, the provider may enter “UNABLE TO DET LAT 1” to identify that they are unable to obtain additional information to specify laterality or they may enter “UNABLE TO DET LAT 2” to identify that the physician is clinically unable to determine laterality.”


For example, if a diagnosis of acute mastoiditis is documented without right or left, the coder should query to get the specific laterality if it is not documented within the record. Code H70.009, Acute mastoiditis without complication, unspecified ear is a CC, but the laterality is not coded. Therefore, the claim will be returned by Medicare for laterality if it goes out on the claim.

Other Payors

We have seen other payors other than Medicare denying unspecified CC/MCC laterality codes. And some payors are denying ANY unspecified ICD-10-CM code if it is principal diagnosis or impacting the case in some way. Each facility must review their payor contracts and guidelines to see if they have any payors identified as denying any unspecified ICD-10-CM codes, and in what circumstances. This sometimes gets overlooked in contract review and negotiation.

Take Away

Coders must be vigilant in identifying unspecified laterality codes that are CC/MCC and must dig into the documentation to find the right, left and in some cases bilateral sides documented. If it is not documented, a query must be executed. Coders must be made aware of payor guidelines other than Medicare that may require them to report laterality on any unspecified codes determined by that payor.


Since 1992, HIA has been the leading provider of compliance audits, coding support services and clinical documentation audit services for hospitals, ambulatory surgery centers, physician groups and other healthcare entities. HIA offers PRN support as well as total outsource support.

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