ICD-10-CM Code R40.20

Unspecified coma

Version 2020 Replaced Code Billable Code No Valid Principal Dx

Valid for Submission

R40.20 is a billable code used to specify a medical diagnosis of unspecified coma. The code is valid for the year 2020 for the submission of HIPAA-covered transactions. The ICD-10-CM code R40.20 might also be used to specify conditions or terms like alcoholic coma, blistering of skin due to coma, blistering of skin due to drug-induced coma, blistering of skin induced by prolonged pressure, coma, coma associated with malnutrition-related diabetes mellitus, etc

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.

Short Description:Unspecified coma
Long Description:Unspecified coma

Replaced Code

This code was replaced in the 2020 ICD-10 code set with the code(s) listed below. The National Center for Health Statistics (NCHS) has published an update to the ICD-10-CM diagnosis codes which became effective October 1, 2019. This code was replaced for the FY 2020 (October 1, 2019 - September 30, 2020).

  • E11.11 - Type 2 diabetes mellitus with ketoacidosis with coma

Tabular List of Diseases and Injuries

The Tabular List of Diseases and Injuries is a list of ICD-10 codes, organized "head to toe" into chapters and sections with guidance for inclusions, exclusions, descriptions and more. The following references are applicable to the code R40.20:

Inclusion Terms

Inclusion Terms
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
  • Coma NOS
  • Unconsciousness NOS

Index to Diseases and Injuries

The Index to Diseases and Injuries is an alphabetical listing of medical terms, with each term mapped to one or more ICD-10 code(s). The following references for the code R40.20 are found in the index:


The following clinical terms are approximate synonyms or lay terms that might be used to identify the correct diagnosis code:

  • Alcoholic coma
  • Blistering of skin due to coma
  • Blistering of skin due to drug-induced coma
  • Blistering of skin induced by prolonged pressure
  • Coma
  • Coma associated with malnutrition-related diabetes mellitus
  • Drug-induced coma
  • Hypothermic coma
  • Hypoxic-ischemic coma
  • Hypoxic-ischemic coma
  • Irreversible coma
  • Ischemic stroke with coma
  • Monocular movements in coma
  • Neurological disorder associated with malnutrition-related diabetes mellitus
  • O/E - comatose
  • O/E - unconscious/comatose
  • Pituitary coma
  • Post-anoxic coma
  • Post-cardiorespiratory arrest coma
  • Post-ictal coma
  • Post-traumatic coma
  • Skin lesion due to drug overdose
  • Spontaneous eye movements in coma
  • Unconscious
  • Unresponsive
  • Uremic coma
  • Uremic encephalopathy

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;632:59 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.
  • CONVULSIVE THERAPY-. convulsions induced in order to treat mental disorders. it is used primarily in the treatment of severe affective disorders and schizophrenia.
  • 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.
  • 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.
  • 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.
  • 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;1410:699 713
  • 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.
  • 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.
  • 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.
  • COMAMONADACEAE-. a family of gram negative aerobic bacteria in the order burkholderiales encompassing the acidovorans rrna complex. some species are pathogenic to plants.

Convert R40.20 to ICD-9

  • 780.01 - Coma (Approximate Flag)

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)

Code History

  • FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016
    (First year ICD-10-CM implemented into the HIPAA code set)
  • FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
  • FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
  • FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
  • FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020

Information for Patients


A coma is a deep state of unconsciousness. An individual in a coma is alive but unable to move or respond to his or her environment. Coma may occur as a complication of an underlying illness, or as a result of injuries, such as brain injury.

A coma rarely lasts more than 2 to 4 weeks. The outcome for coma depends on the cause, severity, and site of the damage. People may come out of a coma with physical, intellectual, and psychological problems. Some people may remain in a coma for years or even decades. For those people, the most common cause of death is infection, such as pneumonia.

NIH: National Institute of Neurological Disorders and Stroke

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