ICD10BillableValid for clinical use

ICD-10 Code Q21.21: Partial atrioventricular septal defect

Q21.21 is a billable ICD-10 diagnosis code used to classify Partial atrioventricular septal defect in medical records and claims. You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records. ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA0).

Reviewed by HealthAssure Clinical TeamUpdated 26 May 2026

What is this code?

ICD-10 codes are diagnosis classification codes used in healthcare records, reporting, coding workflows, and billing support. This code sits within the broader ICD-10 area for Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA0).

When is it used?

  • May be used when a clinician documents partial atrioventricular septal defect in a patient's medical record.
  • May appear in hospital records, claims, referrals, and clinical documentation.
  • This code can be used as a clinically usable diagnosis entry in standardized coding workflows.

What it does not mean

  • A code alone does not explain severity, treatment plan, or outcome.
  • A medical code should not be treated as a substitute for a doctor's diagnosis or advice.

Code hierarchy

chapter
17Congenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA0)
block
Q20-Q28Congenital malformations of the circulatory system
category
Q21Congenital malformations of cardiac septa
category
Q21.2Atrioventricular septal defect
currentQ21.2

Official coding notes

Inclusion terms
  • Incomplete atrioventricular canal
  • Incomplete atrioventricular septal defect
  • Incomplete endocardial cushion defect
  • Ostium primum atrial septal defect (type I) with separate atrioventricular valves
  • Partial atrioventricular canal
  • Partial endocardial cushion defect

Where you may see this code

You may see this code in hospital records, discharge summaries, insurance claims, encounter documentation, referrals, or other healthcare billing and coding records.

Coverage-related procedures and services

CPT 93325high
DOPPLER ECHOCARDIOGRAPHY COLOR FLOW VELOCITY MAPPING (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHY)
Source: CMS coverage guidance
CPT 93320high
DOPPLER ECHOCARDIOGRAPHY, PULSED WAVE AND/OR CONTINUOUS WAVE WITH SPECTRAL DISPLAY (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHIC IMAGING); COMPLETE
Source: CMS coverage guidance
CPT 93321high
DOPPLER ECHOCARDIOGRAPHY, PULSED WAVE AND/OR CONTINUOUS WAVE WITH SPECTRAL DISPLAY (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHIC IMAGING); FOLLOW-UP OR LIMITED STUDY (LIST SEPARATELY IN ADDITION TO CODES FOR ECHOCARDIOGRAPHIC IMAGING)
Source: CMS coverage guidance
HCPCS J0153high
INJECTION, ADENOSINE, 1 MG (NOT TO BE USED TO REPORT ANY ADENOSINE PHOSPHATE COMPOUNDS)
Source: CMS coverage guidance
HCPCS J1245high
INJECTION, DIPYRIDAMOLE, PER 10 MG
Source: CMS coverage guidance
HCPCS J1250high
INJECTION, DOBUTAMINE HYDROCHLORIDE, PER 250 MG
Source: CMS coverage guidance

Coding guidelines

Common synonyms

Partial atrioventricular septal defect

Frequently asked questions

Code details

CodeQ21.21
SystemICD10
Display namePartial atrioventricular septal defect
ChapterCongenital malformations, deformations, chromosomal abnormalities, and genetic disorders (Q00-QA0)
BlockCongenital malformations of the circulatory system

Flags

BillableYes
Valid clinical useYes

Source

SourceICD-10
Version2026-annual
Releaseannual
Year2026

Index terms

Matched terms
CanalCanalDefect, defectiveDefect, defectiveDefect, defectiveDefect, defectiveIncompleteIncompleteIncomplete

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.

ICD-10 Code Q21.21 for Partial atrioventricular septal defect | HealthAssure