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  6. 2024 ICD-10-CM Code R40.21
Version 2024
Non-Billable Code
No Valid Principal Dx

2024 ICD-10-CM Diagnosis Code R40.21

Coma scale, eyes open

ICD-10-CM Code:
R40.21
ICD-10 Code for:
Coma scale, eyes open
Is Billable?
Not Valid for Submission
Code Navigator:

Code Classification

  • Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
    (R00–R99)
    • Symptoms and signs involving cognition, perception, emotional state and behavior
      (R40-R46)
      • Somnolence, stupor and coma
        (R40)

R40.21 is a non-specific and non-billable diagnosis code code, consider using a code with a higher level of specificity for a diagnosis of coma scale, eyes open. The code is not specific and is NOT valid for the year 2024 for the submission of HIPAA-covered transactions. Category or Header define the heading of a category of codes that may be further subdivided by the use of 4th, 5th, 6th or 7th characters.

According to ICD-10-CM guidelines this code should not to be used as a principal diagnosis code when a related definitive diagnosis has been established.

Specific Coding Applicable to Coma scale, eyes open

Non-specific codes like R40.21 require more digits to indicate the appropriate level of specificity. Consider using any of the following ICD-10-CM codes with a higher level of specificity when coding for coma scale, eyes open:

  • R40.211 for Coma scale, eyes open, never - NON-BILLABLE CODE

  • Use R40.2110 for unspecified time - BILLABLE CODE

  • Use R40.2111 for in the field [EMT or ambulance] - BILLABLE CODE

  • Use R40.2112 for at arrival to emergency department - BILLABLE CODE

  • Use R40.2113 for at hospital admission - BILLABLE CODE

  • Use R40.2114 for 24 hours or more after hospital admission - BILLABLE CODE

  • R40.212 for Coma scale, eyes open, to pain - NON-BILLABLE CODE

  • Use R40.2120 for unspecified time - BILLABLE CODE

  • Use R40.2121 for in the field [EMT or ambulance] - BILLABLE CODE

  • Use R40.2122 for at arrival to emergency department - BILLABLE CODE

  • Use R40.2123 for at hospital admission - BILLABLE CODE

  • Use R40.2124 for 24 hours or more after hospital admission - BILLABLE CODE

  • R40.213 for Coma scale, eyes open, to sound - NON-BILLABLE CODE

  • Use R40.2130 for unspecified time - BILLABLE CODE

  • Use R40.2131 for in the field [EMT or ambulance] - BILLABLE CODE

  • Use R40.2132 for at arrival to emergency department - BILLABLE CODE

  • Use R40.2133 for at hospital admission - BILLABLE CODE

  • Use R40.2134 for 24 hours or more after hospital admission - BILLABLE CODE

  • R40.214 for Coma scale, eyes open, spontaneous - NON-BILLABLE CODE

  • Use R40.2140 for unspecified time - BILLABLE CODE

  • Use R40.2141 for in the field [EMT or ambulance] - BILLABLE CODE

  • Use R40.2142 for at arrival to emergency department - BILLABLE CODE

  • Use R40.2143 for at hospital admission - BILLABLE CODE

  • Use R40.2144 for 24 hours or more after hospital admission - BILLABLE CODE

Clinical Information

  • Akinetic Mutism

    a syndrome characterized by a silent and inert state without voluntary motor activity despite preserved sensorimotor pathways and vigilance. bilateral frontal lobe dysfunction involving the anterior cingulate gyrus and related brain injuries are associated with this condition. this may result in impaired abilities to communicate and initiate motor activities. (from adams et al., principles of neurology, 6th ed, p348; fortschr neurol psychiatr 1995 feb;63(2):59-67)

  • Brain Death

    a state of prolonged irreversible cessation of all brain activity, including lower brain stem function with the complete absence of voluntary movements, responses to stimuli, brain stem reflexes, and spontaneous respirations. reversible conditions which mimic this clinical state (e.g., sedative overdose, hypothermia, etc.) are excluded prior to making the determination of brain death. (from adams et al., principles of neurology, 6th ed, pp348-9)

  • Coma

    a profound state of unconsciousness associated with depressed cerebral activity from which the individual cannot be aroused. coma generally occurs when there is dysfunction or injury involving both cerebral hemispheres or the brain stem reticular formation.

  • Coma, Post-Head Injury

    prolonged unconsciousness from which the individual cannot be aroused, associated with traumatic injuries to the brain. this may be defined as unconsciousness persisting for 6 hours or longer. coma results from injury to both cerebral hemispheres or the reticular formation of the brain stem. contributing mechanisms include diffuse axonal injury and brain edema. (from j neurotrauma 1997 oct;14(10):699-713)

  • Comamonadaceae

    a family of gram-negative aerobic bacteria in the order burkholderiales, encompassing the acidovorans rrna complex. some species are pathogenic to plants.

  • Comamonas

    a genus of gram-negative, straight or slightly curved rods which are motile by polar flagella and which accumulate poly-beta-hydroxybutyrate within the cells.

  • Comamonas testosteroni

    a species of gram-negative, aerobic rods formerly called pseudomonas testosteroni. it is differentiated from other comamonas species by its ability to assimilate testosterone and to utilize phenylacetate or maleate as carbon sources.

  • Convulsive Therapy

    convulsions induced in order to treat mental disorders. it is used primarily in the treatment of severe affective disorders and schizophrenia.

  • Delftia acidovorans

    a species of gram-negative rod-shaped bacteria found ubiquitously and formerly called comamonas acidovorans and pseudomonas acidovorans. it is the type species of the genus delftia.

  • Diabetic Coma

    a state of unconsciousness as a complication of diabetes mellitus. it occurs in cases of extreme hyperglycemia or extreme hypoglycemia as a complication of insulin therapy.

  • Glasgow Coma Scale

    a scale that assesses the response to stimuli in patients with craniocerebral injuries. the parameters are eye opening, motor response, and verbal response.

  • Hepatic Encephalopathy

    a syndrome characterized by central nervous system dysfunction in association with liver failure, including portal-systemic shunts. clinical features include lethargy and confusion (frequently progressing to coma); asterixis; nystagmus, pathologic; brisk oculovestibular reflexes; decorticate and decerebrate posturing; muscle spasticity; and bilateral extensor plantar reflexes (see reflex, babinski). electroencephalography may demonstrate triphasic waves. (from adams et al., principles of neurology, 6th ed, pp1117-20; plum & posner, diagnosis of stupor and coma, 3rd ed, p222-5)

  • Hyperglycemic Hyperosmolar Nonketotic Coma

    a serious complication of type 2 diabetes mellitus. it is characterized by extreme hyperglycemia; dehydration; serum hyperosmolarity; and depressed consciousness leading to coma in the absence of ketosis and acidosis.

  • Insulin Coma

    severe hypoglycemia induced by a large dose of exogenous insulin resulting in a coma or profound state of unconsciousness from which the individual cannot be aroused.

  • Santalaceae

    a plant family of the order santalales, subclass rosidae, class magnoliopsida. they are parasites that form connections (haustoria) to their hosts to obtain water and nutrients. the one-seeded fruit may be surrounded by a brightly colored nut-like structure.

  • Frontal Lobe

    the part of the cerebral hemisphere anterior to the central sulcus, and anterior and superior to the lateral sulcus.

  • Reticular Formation

    a region extending from the pons & medulla oblongata through the mesencephalon, characterized by a diversity of neurons of various sizes and shapes, arranged in different aggregations and enmeshed in a complicated fiber network.

  • Delftia

    a genus of gram-negative, strictly aerobic chemoorganotrophic bacteria, in the family comamonadaceae.

Tabular List of Diseases and Injuries

The following annotation back-references are applicable to this diagnosis code. The Tabular List of Diseases and Injuries is a list of ICD-10-CM codes, organized "head to toe" into chapters and sections with coding notes and guidance for inclusions, exclusions, descriptions and more.


7th Character Note

7th Character Note
Certain ICD-10-CM categories have applicable 7th characters. The applicable 7th character is required for all codes within the category, or as the notes in the Tabular List instruct. The 7th character must always be the 7th character in the data field. If a code that requires a 7th character is not 6 characters, a placeholder X must be used to fill in the empty characters.
  • The following appropriate 7th character is to be added to subcategory R40.21-:

7th Character

7th Character
Indicates that a seventh character is to be assigned to codes in a subcategory.
  • 0 - unspecified time
  • 1 - in the field EMT or ambulance
  • 2 - at arrival to emergency department
  • 3 - at hospital admission
  • 4 - 24 hours or more after hospital admission

Code History

  • FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
  • FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
  • FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
  • FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.