2027 ICD-10-CM Diagnosis Code Q34.1Congenital cyst of mediastinum

ICD-10-CM Codes›Q00-Q99›Q30-Q34›Q34

ICD-10-CM Q34.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

Q34.1 is a billable ICD-10-CM diagnosis code for congenital cyst of mediastinum. 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
Q34.1
Billable Status
Yes — Valid for Submission
Code Describes
Congenital cyst of mediastinum
Short Description
Congenital cyst of mediastinum
Same as the full description in the CMS dataset.
Parent Code
Q34
Other congenital malformations of respiratory system

Code Classification

ChapterQ00-Q99Congenital malformations, deformations and chromosomal abnormalities
SectionQ30-Q34Congenital malformations of the respiratory system
CategoryQ34Other congenital malformations of respiratory system
This CodeQ34.1Congenital cyst of mediastinum

Present on Admission (POA)Billing

Q34.1 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.

  • Congenital cyst of mediastinum
  • Cyst of mediastinum

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to Q34.1: its own notes plus those printed at Q34 and 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.

From Q34 Other congenital malformations of respiratory system applies to 4 codes
  • congenital central alveolar hypoventilation syndrome (G47.35)
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 Q34.1, its category, or a range that includes it.

Code Also 1

These codes say Q34.1 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

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?
  • What are the treatments for birth defects?
  • 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 Q34.1 to ICD-9-CMHistory

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

ICD-9-CM
748.8 Respiratory 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 Q34.1Overview

What is the ICD-10 code for congenital cyst of mediastinum?

The ICD-10-CM code for congenital cyst of mediastinum is Q34.1 (sometimes written as Q341). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is Q34.1 (Other congenital malformations of respiratory system) a billable code?

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

What MS-DRG does Q34.1 group to?

When congenital cyst of mediastinum 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 Q34.1 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 congenital cyst of mediastinum 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 Q34.1?

Under the General Equivalence Mappings, congenital cyst of mediastinum converts to ICD-9-CM 748.8 (respiratory anomaly NEC). The mapping is approximate, so confirm the match fits the documentation.