2027 ICD-10-CM Diagnosis Code Q33.1Accessory lobe of lung

ICD-10-CM Codes›Q00-Q99›Q30-Q34›Q33

ICD-10-CM Q33.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q33.1 is a billable ICD-10-CM diagnosis code for accessory lobe of lung. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 205 through 206. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Respiratory congenital malformations.

Code Identity

ICD-10-CM Code
Q33.1
Billable Status
Yes — Valid for Submission
Code Describes
Accessory lobe of lung
Short Description
Accessory lobe of lung
Same as the full description in the CMS dataset.
Parent Code
Q33
Congenital malformations of lung

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ30-Q34Congenital malformations of the respiratory system
CategoryQ33Congenital malformations of lung
This CodeQ33.1Accessory lobe of lung

Present on Admission (POA)Billing

Q33.1 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the respiratory system (Q30-Q34).

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Accessory lobe of lung
  • Accessory lung
  • Accessory structure of lower respiratory tract
  • Azygos lobe of lung
  • Trilobed left lung

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q33.1: its own notes plus those printed at Chapter 17. A note printed at a category, block or chapter applies to every code under it.

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Azygos lobe (fissured), lung

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.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • inborn errors of metabolism (E70-E88)

Notes

General instructions on how these codes are used.

From Chapter 17 (Q00-QA1) Congenital malformations, deformations and chromosomal abnormalities applies to 900 codes
  • Codes from this chapter are not for use on maternal records

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name Q33.1, its category, or a range that includes it.

Code Also 1

These codes say Q33.1 may also be needed to fully describe the condition. The note gives no sequencing direction.

  • P28 Other respiratory conditions originating in the perinatal period
    if applicable, congenital malformations of the respiratory system (Q30-Q34) names Q30-Q34, which includes this code

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR MAL007
Respiratory congenital malformations
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Supernumerary Lung Lobe

    lung tissue that is separated by an accessory fissure.

Patient EducationClinical

Birth Defects

A birth defect is a problem that happens while a baby is developing in the mother's body. Most birth defects happen during the first 3 months of pregnancy. One out of every 33 babies in the United States is born with a birth defect.

The full article covers:

  • What are birth defects?
  • What causes birth defects?
  • Who is at risk of having a baby with birth defects?
  • How are birth defects diagnosed?
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  • Can birth defects be prevented?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert Q33.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
748.69 Lung anomaly NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About Q33.1Overview

What is the ICD-10 code for accessory lobe of lung?

The ICD-10-CM code for accessory lobe of lung is Q33.1 (sometimes written as Q331). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q33.1 (Congenital malformations of lung) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report accessory lobe of lung on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does Q33.1 group to?

When accessory lobe of lung is the principal diagnosis on an inpatient stay, it groups to MS-DRG 206, 205, with relative weights from 0.9255 to 1.8244 depending on complications. Higher weights mean higher Medicare reimbursement.

Is Q33.1 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 accessory lobe of lung on inpatient claims. The code appears in the Congenital malformations of the respiratory system (Q30-Q34) range of the CMS exempt list.

What is the ICD-9 equivalent of Q33.1?

Under the General Equivalence Mappings, accessory lobe of lung converts to ICD-9-CM 748.69 (lung anomaly NEC). The mapping is approximate, so confirm the match fits the documentation.