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Opportunity for Clarification with Glasgow Coma Scale (GCS) Changes in FY 2021

Posted By Marie Thomas
medical coding experts

Last month, the American Hospital Association (AHA) hosted a webinar on Tuesday, September 22nd bringing to light modifications for the FY 2021 Coding updates. Their discussion included the following key code changes:

  • Sickle-Cell Disorders
  • Immunodeficiency Status
  • Cytokine Release Syndrome
  • Withdrawal Syndrome in Substance Use and Abuse
  • Cerebrospinal Fluid Leak
  • Neonatal Cerebral Infarction
  • Hepatic Fibrosis
  • Poisoning by, adverse effect of and underdosing of synthetic narcotics
  • New Z codes and External cause of morbidity and mortality codes

During the webinar presentation, changes to the Glasgow Coma Scale (GCS) guidelines triggered additional questions that were not clear in the guideline. 

To clarify the confusion, I have highlighted the misunderstanding in the guideline below:

Official Coding Guidelines 2021 - pg. 78-79

18.e. Coma scale the coma scale codes (R40.2-) can be used in conjunction with traumatic brain injury codes. These codes are primarily for use by trauma registries, but they may be used in any setting where this information is collected. The coma scale codes should be sequenced after the diagnosis code(s) These codes, one from each subcategory, are needed to complete the scale. The 7th character indicates when the scale was recorded. The 7th character should match all three codes. At a minimum, report the initial score documented on the presentation at your facility. This may be a score from the emergency medical technician (EMT) or in the emergency department. If desired, a facility may choose to capture multiple coma scale scores. Assign code R40.24, Glasgow coma scale, total score, when only the total score is documented in the medical record and not the individual score(s). Do not report codes for individual or total Glasgow coma scale scores for a patient with a medically induced coma or a sedated patient. (See Section I.B.14 for coma scale documentation by clinicians other than patient's provider)

Section I.B.14: Codes that describe symptoms and signs, as opposed to diagnoses, are acceptable for reporting purposes when a related definitive diagnosis has not been established (confirmed) by the provider. Chapter 18 of ICD-10-CM, Symptoms, Signs, and Abnormal Clinical and Laboratory Findings, Not Elsewhere Classified (codes R00.0 - R99) contains many, but not all, codes for symptoms.

AHA’s Director of Coding and Classification, Nelly Leon-Chisen, RHIA further explained that the initial intent of GCS was associated with trauma and the assignment of GCS to other conditions had moved the initial intent away from that primary purpose. The 2021 guideline simply moved the GCS assignment back to trauma as originally intended by the Editorial Advisory Board.  

We are hopeful that the 4th Quarter Coding Clinic will address this further, but in the meantime, we recommend GCS only be assigned in the setting of trauma. 

Finally, it is important to note that there is a query opportunity to ensure the level of severity for patients with low (3 – 8) GCS scores are captured yielding MS-DRG impacted MCC when coma is supported.

What is the Glasgow Coma Scale (GCS)?

To recap, according to Wikipedia "The Glasgow Coma Scale (GCS) is a neurological scale which aims to give a reliable and objective way of recording the state of a person's consciousness for initial as well as subsequent assessment. A person is assessed against the criteria of the scale, and the resulting points give a person's score between 3 (indicating deep unconsciousness) and either 14 (original scale)" or 15 (more widely used, modified, or revised scale). ("Glasgow Coma Scale (GCS)").

Altered levels of consciousness may be described in different ways in the documentation.  Altered mental status, stupor, drowsiness, somnolence, lethargy may be some of the terms used when a patient has been assessed using GCS.  Three (3) being the lowest level of consciousness and fifteen (15) being the highest level of consciousness.



American Hospital Association (AHA). (2020, September 22). FY 2021 Updates Part 1: ICD-10-CM Codes and Official Guidelines for Coding and Reporting [Webinar] https://www.aha.org/education-events/fy-2021-updates-part-1-icd-10-cm-codes-and-official-guidelines-coding-and

“Glasgow Coma Scale (GCS)”. (2020, October). In Wikipedia. Retrieved from https://en.wikipedia.org/wiki/Glasgow_Coma_Scale

ICD-10-CM Official Guidelines for Coding and Reporting FY 2021 [PDF]. Centres for Medicare and Medicaid Services (CMS). retrieved from https://www.cdc.gov/nchs/data/icd/10cmguidelines-FY2021.pdf



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