Y28.9XXA Contact with unspecified sharp object, undetermined intent, initial encounter

ICD-10-CM Code Y28.9XXA: Contact with unspecified sharp object, undetermined intent, initial encounter

ICD-10-CM code Y28.9XXA denotes an initial encounter for contact with an unspecified sharp object where the intent is undetermined. This code is included in state-level violent injury surveillance lists. Mortality coding guidance establishes that undetermined intent applies when available information cannot distinguish between accidental and intentional injury. 5 2 4

Plain-language overview

Code Y28.9XXA describes an injury resulting from contact with an unspecified sharp object where it cannot be determined if the injury was accidental or purposefully inflicted. 5

What this code represents

The official display label for Y28.9XXA is contact with unspecified sharp object, undetermined intent, initial encounter, categorizing it within external causes of morbidity. 5

The Illinois Department of Public Health includes Y28.9XXA within a published list of ICD-10 violent injury inclusion codes, whereas a clinical research study lists Y28.9XXA among administrative data codes observed in a hospital-based violence intervention program. 5 3

Coding details

The code Y28.9XXA appears in source materials with the seventh character 'A' and the phrase 'initial encounter' in its official label. 5

External cause codes for events of undetermined intent, such as Y28.9XXA, are assigned when statements indicate uncertainty like 'accident or suicide' or 'undetermined' regarding whether the injury was accidental or intentional. 2 4

Documentation considerations

Documentation elements that support assigning an undetermined intent code include explicit notations of 'unknown' or 'open verdict' when it is not specified whether an injury was accidental or inflicted with intent to harm. 2 4

What the sources add

The Illinois Department of Public Health source explicitly lists Y28.9XXA as a violent injury inclusion code, while the CDC mortality coding instructions provide the framework for classifying external causes of injury with undetermined intent. 5 2

A population-based data linkage study in Wales utilized ICD-10 codes Y10 through Y34 to identify deaths of undetermined intent, establishing a broader operational context for how undetermined intent categories are used in mortality data. 1

Sources

1. Suicide Information Database-Cymru: a protocol for a population-based, routinely collected data linkage study to explore risks and patterns of healthcare contact prior to suicide to identify opportunities for intervention — pmc.ncbi.nlm.nih.gov; accessed 2026-07-25.
2. Instructions for Classifying Multiple Causes of Death, 2019 – Section V — cdc.gov; accessed 2026-07-25.
3. Examining Adverse Childhood Experiences and Black Youth’s Engagement in a Hospital-based Violence Intervention Program using Administrative Data — pmc.ncbi.nlm.nih.gov; accessed 2026-07-25.
4. Instructions for Classifying the Underlying Cause-of-Death, ICD-10, 2025 — cdc.gov; accessed 2026-07-25.
5. Violent Injury ICD-10 Inclusion Codes — dph.illinois.gov; accessed 2026-07-25.