2027 ICD-10-CM Diagnosis Code Q26.1Persistent left superior vena cava
ICD-10-CM Codes›Q00-Q99›Q20-Q28›Q26
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- POA Exempt
- Chronic Condition
Q26.1 is a billable ICD-10-CM diagnosis code for persistent left superior vena cava. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 306 through 307. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 9 closely related codes. The code is exempt from POA reporting. Coders also document this condition as left superior caval vein persisting to coronary sinus. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Cardiac and circulatory congenital anomalies.
Q26.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 191 for payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q26.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the circulatory system (Q20-Q28).
Medicare Risk Adjustment (HCC)Billing
Q26.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Left superior caval vein persisting to coronary sinus
- Left superior caval vein persisting to coronary sinus and then to right sided atrium
- Left superior caval vein persisting to left sided atrium
- Left superior caval vein persisting to right atrium and left atrium
- Left superior caval vein persisting to right sided atrium
- Persistent left superior vena cava
- Persistent left superior vena cava connecting through coronary sinus to left sided atrium
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q26.1: its own notes plus those printed at Chapter 17. A note printed at a category, block or chapter applies to every code under it.
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
Notes
General instructions on how these codes are used.
- Codes from this chapter are not for use on maternal records
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Malformation (congenital) See Also: Anomaly;
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Persistent Left Superior Vena Cava
finding of the superior vena cava on the left instead of the usual right side of the ascending aorta. in bilateral superior vena cava it is found on both sides.
Patient EducationClinical
Aneurysms
An aneurysm is a bulge or "ballooning" in the wall of an artery. Arteries are blood vessels that carry oxygen-rich blood from the heart to other parts of the body. If an aneurysm grows large, it can burst and cause dangerous bleeding or even death.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q26.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q26.1Overview
What is the ICD-10 code for persistent left superior vena cava?
The ICD-10-CM code for persistent left superior vena cava is Q26.1 (sometimes written as Q261). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q26.1 (Congenital malformations of great veins) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report persistent left superior vena cava on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q26.1 group to?
When persistent left superior vena cava is the principal diagnosis on an inpatient stay, it groups to MS-DRG 306, 307, with relative weights from 0.9146 to 1.5457 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q26.1 a CC or MCC?
CMS lists Q26.1 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 9 closely related codes in its exclusion list.
Is Q26.1 exempt from POA reporting?
Yes. CMS lists this code among those exempt from present on admission reporting, so hospitals do not assign a POA indicator for persistent left superior vena cava on inpatient claims. The code appears in the Congenital malformations of the circulatory system (Q20-Q28) range of the CMS exempt list.
Does Q26.1 risk-adjust for Medicare Advantage payment?
Not for Medicare Advantage: Q26.1 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the RxHCC Part D (V08) category 191 (Ventricular Septal Defect and Major Congenital Heart Disorders).
