ICD-10-CM 2027
ICD-10 code for appendix agenesis
Congenital absence, atresia and stenosis of other parts of large intestine
From the official ICD-10-CM alphabetic index entry “Agenesis › appendix”. Page updated September 29, 2026.
About coding appendix agenesis
The ICD-10-CM code for appendix agenesis is Q42.8 (Congenital absence, atresia and stenosis of other parts of large intestine).
Within Q42, choose Q42.8 (other parts of large intestine) only when documentation doesn't support a more specific option: rectum with fistula (Q42.0), rectum without fistula (Q42.1), anus with fistula (Q42.2), anus without fistula (Q42.3) and part unspecified (Q42.9).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 393 (Other Digestive System Diagnoses with MCC, relative weight 1.5881), DRG 394 (Other Digestive System Diagnoses with CC, relative weight 0.9228) and DRG 395 (Other Digestive System Diagnoses without CC/MCC, relative weight 0.6382), in MDC 06 (Diseases and Disorders of the Digestive System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
Common questions about appendix agenesis ICD-10 codes
What is the ICD-10 code for appendix agenesis?
- Q42.8 — Congenital absence, atresia and stenosis of other parts of large intestine.
Is Q42.8 billable?
- Yes. Q42.8 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can Q42.8 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict Q42.8 as a principal diagnosis.
Is Q42.8 a CC or MCC?
- Q42.8 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.