Y21.2XXA ICD-10-CM Code: Drowning and submersion while in swimming pool, undetermined intent, initial encounter

7th Character Guide

"The appropriate 7th character is to be added to each code from category Y21"

• A — initial encounter (this page’s code)
• D — subsequent encounter
• S — sequela

How the encounter character is assigned. “Initial encounter” means the patient is receiving active treatment for the condition — it is not limited to the first visit, and a different or new provider giving active treatment still assigns it. “Subsequent encounter” covers care during the healing or recovery phase after active treatment. “Sequela” is for complications or conditions that arise as a direct result of the original condition.

ICD-10-CM Official Guidelines for Coding and Reporting, Section I.C.19.a (paraphrased by MedCoder).

Variant codes in this family

Y21.2XXA, Y21.2XXD, Y21.2XXS

Character meanings are CMS's official 7th-character extensions for this family, as carried in each variant code's official description; variant codes are registry rows. The explanation of how the encounter character is assigned is MedCoder editorial, distinct from the official content above it.

Coder workflow for Y21.2XXA

MedCoder structured workflow — derived from this code’s own official record

Before you code Y21.2XXA

1. A 7th character is required in this family. Confirm the documented encounter: initial (active treatment), subsequent (healing or recovery phase), or sequela. This page’s code carries “A”. “Initial” means active treatment, not the first visit (Guidelines I.C.19.a).

   See the 7th Character Guide · Guide: 7th characters: initial, subsequent, sequela →

2. An external cause code is reported in addition to the code for the injury or condition, never as the principal or first-listed diagnosis. Confirm the cause, intent, place of occurrence, activity and status where the record documents them, and assign the 7th character that matches the injury code. External cause coding guidelines (Guidelines I.C.20.a).

Choose the right path

1. Is the encounter phase documented — active treatment, healing or recovery, or a sequela?
   Yes → Assign the matching 7th character; the variant codes are in the 7th Character Guide.
   No → The code is invalid without its 7th character — query for the missing element.

Consider Y21.2XXA. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

Encounter type

Active treatment, healing or recovery phase, or sequela — the basis of the 7th character (Guidelines I.C.19.a).

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Don’t confuse Y21.2XXA with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of Y21.2XXA — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• Y21.2XXD— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a subsequent encounter moves the case to Y21.2XXD.

  Full comparison: Y21.2XXA vs Y21.2XXD →

• Y21.2XXS— Encounter relationship (Review)

  Same underlying diagnosis, different encounter phase.

  The same diagnosis at a different phase of care; one encounter takes one 7th character.

  What moves you there: Documentation of a sequela moves the case to Y21.2XXS.

  Full comparison: Y21.2XXA vs Y21.2XXS →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• Principal-diagnosis restriction. External cause of morbidity codes (V, W, X and Y) describe the circumstance that caused an injury, not the condition treated. The Medicare Code Editor rejects them as a principal diagnosis; sequence the injury or condition first and report this code as secondary.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Clinical classification (AHRQ CCSR):EXT002 — External cause codes: drowning/submersion; initial encounter; EXT023 — External cause codes: intent of injury, undetermined.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (External cause codes: drowning/submersion; initial encounter, External cause codes: intent of injury, undetermined).

W73.XXXA — Other specified cause of accidental non-transport drowning and submersion, initial encounter, W74.XXXA — Unspecified cause of accidental drowning and submersion, initial encounter, X71.0XXA — Intentional self-harm by drowning and submersion while in bathtub, initial encounter, X71.1XXA — Intentional self-harm by drowning and submersion while in swimming pool, initial encounter, X71.2XXA — Intentional self-harm by drowning and submersion after jump into swimming pool, initial encounter, X71.3XXA — Intentional self-harm by drowning and submersion in natural water, initial encounter, X71.8XXA — Other intentional self-harm by drowning and submersion, initial encounter, X71.9XXA — Intentional self-harm by drowning and submersion, unspecified, initial encounter, X92.0XXA — Assault by drowning and submersion while in bathtub, initial encounter, X92.1XXA — Assault by drowning and submersion while in swimming pool, initial encounter, X92.2XXA — Assault by drowning and submersion after push into swimming pool, initial encounter, X92.3XXA — Assault by drowning and submersion in natural water, initial encounter, X92.8XXA — Other assault by drowning and submersion, initial encounter, X92.9XXA — Assault by drowning and submersion, unspecified, initial encounter, Y21.0XXA — Drowning and submersion while in bathtub, undetermined intent, initial encounter, Y21.1XXA — Drowning and submersion after fall into bathtub, undetermined intent, initial encounter, Y21.3XXA — Drowning and submersion after fall into swimming pool, undetermined intent, initial encounter, Y21.4XXA — Drowning and submersion in natural water, undetermined intent, initial encounter, Y21.8XXA — Other drowning and submersion, undetermined intent, initial encounter, Y21.9XXA — Unspecified drowning and submersion, undetermined intent, initial encounter, +455 more

Contextual Map

Every relationship of Y21.2XXA in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Hierarchy

• V00-Y99 — Chapter 20: External Causes of Morbidity (V00-Y99) (V00-Y99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21-Y33 — Event of undetermined intent[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• EXT002 — External cause codes: drowning/submersion; initial encounter[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• EXT023 — External cause codes: intent of injury, undetermined[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

Nearest codes (28)

• Y21 — Drowning and submersion, undetermined intent[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.0 — Drowning and submersion while in bathtub, undetermined intent[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.0XXA — Drowning and submersion while in bathtub, undetermined intent, initial encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.0XXD — Drowning and submersion while in bathtub, undetermined intent, subsequent encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.0XXS — Drowning and submersion while in bathtub, undetermined intent, sequela[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.1 — Drowning and submersion after fall into bathtub, undetermined intent[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.1XXA — Drowning and submersion after fall into bathtub, undetermined intent, initial encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• Y21.1XXD — Drowning and submersion after fall into bathtub, undetermined intent, subsequent encounter[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 20 more

Change history

• FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Common coding questions

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to Y21.2XXA in its code family, with their registry titles.

• Y21.1 — Drowning and submersion after fall into bathtub, undetermined intent
• Y21.1XXA — Drowning and submersion after fall into bathtub, undetermined intent, initial encounter
• Y21.1XXD — Drowning and submersion after fall into bathtub, undetermined intent, subsequent encounter
• Y21.1XXS — Drowning and submersion after fall into bathtub, undetermined intent, sequela
• Y21.2 — Drowning and submersion while in swimming pool, undetermined intent
• Y21.2XXD — Drowning and submersion while in swimming pool, undetermined intent, subsequent encounter
• Y21.2XXS — Drowning and submersion while in swimming pool, undetermined intent, sequela
• Y21.3 — Drowning and submersion after fall into swimming pool, undetermined intent
• Y21.3XXA — Drowning and submersion after fall into swimming pool, undetermined intent, initial encounter
• Y21.3XXD — Drowning and submersion after fall into swimming pool, undetermined intent, subsequent encounter

View all codes in the Y21 family