R99
Ill-defined and unknown cause of mortality
Ill-defined and unknown cause of mortality (R99) is a block within ICD-10-CM Chapter 18: Symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified. It holds 1 category.
Categories in R99
Source
ICD-10-CM FY2026. Centers for Medicare & Medicaid Services (CMS) / National Center for Health Statistics (NCHS), “2026 ICD-10-CM Code Descriptions in Tabular Order” (icd10cm_order_2026.txt). Download the original file from cms.gov. Public domain (US Government work). Descriptors, billable flags and instructional notes on this page are reproduced from that file without modification. Krasyn adds no clinical guidance.