ICD-10-CM › R00-R99 › R99 › R codes › R99

R99

Ill-defined and unknown cause of mortality

ValidICD-10-CM diagnosis code.

Valid for claims with a date of service in the current code year.

Valid FY2016 onwards.

What has happened to this code

Every change the publisher made, from 2007 to now. Entries marked draft are from the pre-implementation releases: ICD-10 took effect on 1 October 2015, so nothing before FY2016 was ever valid on a claim.

  1. FY2007 Added to the draft code set draft Ill-defined and unknown cause of mortality

Official coding rules

Published by CDC for FY2027. A rule attached to a category binds every code beneath it, so the rules inherited from this code's ancestors are shown with the code they come from.

This code

Also known as

  • Death (unexplained) NOS
  • Unspecified cause of mortality

How CDC's index refers to this code

Wording from the official alphabetic index. Much of it appears nowhere in the code description, which is why a search for the everyday phrase so often finds nothing.