2022 ICD-10-CM Diagnosis Code R99

Ill-defined and unknown cause of mortality

    2016 2017 2018 2019 2020 2021 2022 Billable/Specific Code
  • R99 is a billable/specific ICD-10-CM code that can be used to indicate a diagnosis for reimbursement purposes.
  • The 2022 edition of ICD-10-CM R99 became effective on October 1, 2021.
  • This is the American ICD-10-CM version of R99 - other international versions of ICD-10 R99 may differ.
Applicable To
  • Death (unexplained) NOS
  • Unspecified cause of mortality
The following code(s) above R99 contain annotation back-references
Annotation Back-References
In this context, annotation back-references refer to codes that contain:
  • Applicable To annotations, or
  • Code Also annotations, or
  • Code First annotations, or
  • Excludes1 annotations, or
  • Excludes2 annotations, or
  • Includes annotations, or
  • Note annotations, or
  • Use Additional annotations
that may be applicable to R99:
  • R00-R99
    2022 ICD-10-CM Range R00-R99

    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified

    • This chapter includes symptoms, signs, abnormal results of clinical or other investigative procedures, and ill-defined conditions regarding which no diagnosis classifiable elsewhere is recorded.
    • Signs and symptoms that point rather definitely to a given diagnosis have been assigned to a category in other chapters of the classification. In general, categories in this chapter include the less well-defined conditions and symptoms that, without the necessary study of the case to establish a final diagnosis, point perhaps equally to two or more diseases or to two or more systems of the body. Practically all categories in the chapter could be designated 'not otherwise specified', 'unknown etiology' or 'transient'. The Alphabetical Index should be consulted to determine which symptoms and signs are to be allocated here and which to other chapters. The residual subcategories, numbered .8, are generally provided for other relevant symptoms that cannot be allocated elsewhere in the classification.
    • The conditions and signs or symptoms included in categories R00-R94 consist of:
    • (a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
    • (b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
    • (c) provisional diagnosis in a patient who failed to return for further investigation or care;
    • (d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
    • (e) cases in which a more precise diagnosis was not available for any other reason;
    • (f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
    Type 2 Excludes
    • abnormal findings on antenatal screening of mother (O28.-)
    • certain conditions originating in the perinatal period (P04-P96)
    • signs and symptoms classified in the body system chapters
    • signs and symptoms of breast (N63, N64.5)
    Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified
Approximate Synonyms
  • Death in less than 24 hours from onset of symptoms
  • Death less than 24 hr from onset of symptoms
  • Instantaneous death
  • Sudden infant death syndrome
  • Unattended death
ICD-10-CM R99 is grouped within Diagnostic Related Group(s) (MS-DRG v39.0):
  • 951 Other factors influencing health status

Convert R99 to ICD-9-CM

Code History
  • 2016 (effective 10/1/2015): New code (first year of non-draft ICD-10-CM)
  • 2017 (effective 10/1/2016): No change
  • 2018 (effective 10/1/2017): No change
  • 2019 (effective 10/1/2018): No change
  • 2020 (effective 10/1/2019): No change
  • 2021 (effective 10/1/2020): No change
  • 2022 (effective 10/1/2021): No change

Diagnosis Index entries containing back-references to R99:
  • Cot death R99
  • Crib death R99
  • Death (cause unknown) (of) (unexplained) (unspecified cause) R99
  • Syndrome - see also Disease
    • crib death R99

ICD-10-CM Codes Adjacent To R99
R94.6 Abnormal results of thyroid function studies
R94.7 Abnormal results of other endocrine function studies
R94.8 Abnormal results of function studies of other organs and systems
R97 Abnormal tumor markers
R97.0 Elevated carcinoembryonic antigen [CEA]
R97.1 Elevated cancer antigen 125 [CA 125]
R97.2 Elevated prostate specific antigen [PSA]
R97.20 Elevated prostate specific antigen [PSA]
R97.21 Rising PSA following treatment for malignant neoplasm of prostate
R97.8 Other abnormal tumor markers
R99 Ill-defined and unknown cause of mortality
S00 Superficial injury of head
S00.0 Superficial injury of scalp
S00.00 Unspecified superficial injury of scalp
S00.00XA …… initial encounter
S00.00XD …… subsequent encounter
S00.00XS …… sequela
S00.01 Abrasion of scalp
S00.01XA …… initial encounter
S00.01XD …… subsequent encounter
S00.01XS …… sequela

Reimbursement claims with a date of service on or after October 1, 2015 require the use of ICD-10-CM codes.