ICD-10-CM > Q00-QA0 > Q20-Q28 > Q21 > Q21.2 > Q21.20 Q21.20 Atrioventricular septal defect, unspecified as to partial or complete Billable/Specific Copy Code Copy Description Applicable To Atrioventricular canal, NOSEndocardial cushion defect NOSOstium primum atrial septal defect (type I) NOS