Q28.1 Other malformations of precerebral vessels

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis. Exempt from present-on-admission (POA) reporting.

Applicable to

• Congenital malformation of precerebral vessels NOS
• Congenital precerebral aneurysm (nonruptured)

Applies from Q28 Other congenital malformations of circulatory system

Excludes1 (never code together)

• congenital aneurysm NOS (Q27.8)
• congenital coronary aneurysm (Q24.5)
• ruptured cerebral arteriovenous malformation (I60.8)
• ruptured malformation of precerebral vessels (I72.0)

Excludes2 (not included here)

• congenital peripheral aneurysm (Q27.8)
• congenital pulmonary aneurysm (Q25.79)
• congenital retinal aneurysm (Q14.1)

MS-DRG index

Defines the logic of DRG(s) 299-301 in MDC 05.

Approximate ICD-9-CM (GEMs)

• 747.89 Other specified anomalies of circulatory system (approximate)

Code annotations containing back-references to Q28.1

Back-references to Q28.1

• Type 2 Excludes: I72 Other aneurysm ("dissection of precerebral artery, congenital (nonruptured) (Q28.1)")
• Type 2 Excludes: I72 Other aneurysm ("precerebral artery, congential (nonruptured) (Q28.1)")
• Type 2 Excludes: Q27 Other congenital malformations of peripheral vascular system ("anomalies of cerebral and precerebral vessels (Q28.0-Q28.3)")

Back-references to Q28

• Code Also: I27.21 Secondary pulmonary arterial hypertension ("congenital heart disease (Q20-Q28)")
• Type 1 Excludes: I67.1 Cerebral aneurysm, nonruptured ("congenital cerebral aneurysm, nonruptured (Q28.-)")
• Type 2 Excludes: P29 Cardiovascular disorders originating in the perinatal period ("congenital malformations of the circulatory system (Q20-Q28)")
• Code Also: Z71.87 Encounter for pediatric-to-adult transition counseling ("congenital malformations of the circulatory system (Q20-Q28)")

Diagnosis Index entries for Q28.1

• Aberrant (congenital) › artery (peripheral) › basilar NEC
• Aberrant (congenital) › artery (peripheral) › precerebral
• Aberrant (congenital) › artery (peripheral) › vertebral
• Aberrant (congenital) › vein (peripheral) NEC › precerebral
• Absence (of) (organ or part) (complete or partial) › vein (peripheral) congenital NEC › precerebral
• Aneurysm (anastomotic) (artery) (cirsoid) (diffuse) (false) (fusiform) (multiple) (saccular) › precerebral › congenital (nonruptured)
• Anomaly, anomalous (congenital) (unspecified type) › artery (peripheral) › basilar NEC
• Anomaly, anomalous (congenital) (unspecified type) › artery (peripheral) › vertebral NEC
• Anomaly, anomalous (congenital) (unspecified type) › precerebral vessel
• Anomaly, anomalous (congenital) (unspecified type) › vessel (s) › precerebral
• Dissection › artery › precerebral › congenital (nonruptured)
• Dissection › precerebral artery, congenital (nonruptured)
• Distribution vessel, atypical › precerebral
• Malformation (congenital) › precerebral vessels

Nearby codes

• Q28 Other congenital malformations of circulatory system
• Q28.0 Arteriovenous malformation of precerebral vessels
• Q28.1 Other malformations of precerebral vessels (this code)
• Q28.2 Arteriovenous malformation of cerebral vessels
• Q28.3 Other malformations of cerebral vessels
• Q28.8 Other specified congenital malformations of circulatory system
• Q28.9 Congenital malformation of circulatory system, unspecified