2027 ICD-10-CM Diagnosis Code Q00.0Anencephaly
ICD-10-CM Codes›Q00-Q99›Q00-Q07›Q00
- Billable — Valid for Submission
- MCC — Major Complication or Comorbidity
- Risk Adjusts — HCC 182
- POA Exempt
- Chronic Condition
Q00.0 is a billable ICD-10-CM diagnosis code for anencephaly. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 91 through 93, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 3 closely related codes. The code is exempt from POA reporting. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nervous system congenital anomalies.
For Medicare Advantage risk adjustment, Q00.0 maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries) under the V28 model, adding a risk factor of about 0.478 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Present on Admission (POA)Billing
Q00.0 is exempt from POA reporting on inpatient claims to general acute care hospitals. Review the other POA exempt codes in Congenital malformations of the nervous system (Q00-Q07).
Medicare Risk Adjustment (HCC)Billing
Q00.0 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
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.
- Acardia
- Acephalobrachius
- Acephalocheiria
- Acephaly
- Amyelencephalus
- Anencephalus
- Anencephaly without rachischisis
- Congenital absence of left hand
- Congenital absence of right hand
- Congenital brain aplasia
- Hemianencephaly
- Hemicephaly
- Holoacardius acephalus
- Holoanencephaly
- Incomplete anencephaly
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to Q00.0: 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.
- Acephaly
- Acrania
- Amyelencephaly
- Hemianencephaly
- Hemicephaly
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.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name Q00.0, its category, or a range that includes it.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Acrania Q00.0
brain Q00.0
anencephaly Q00.0
Anomaly, anomalous (congenital) (unspecified type) Q89.9
anencephaly Q00.0
hemianencephaly Q00.0
hemicephaly Q00.0
hemicrania Q00.0
anencephaly Q00.0
Hemianencephaly Q00.0
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Anencephaly
a malformation of the nervous system caused by failure of the anterior neuropore to close. infants are born with intact spinal cords, cerebellums, and brainstems, but lack formation of neural structures above this level. the skull is only partially formed but the eyes are usually normal. this condition may be associated with folate deficiency. affected infants are only capable of primitive (brain stem) reflexes and usually do not survive for more than two weeks. (from menkes, textbook of child neurology, 5th ed, p247)
Patient EducationClinical
Neural Tube Defects
Neural tube defects are birth defects of the brain, spine, or spinal cord. They happen in the first month of pregnancy, often before a woman even knows that she is pregnant. The two most common neural tube defects are spina bifida and anencephaly. In spina bifida, the fetal spinal column doesn't close completely.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert Q00.0 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About Q00.0Overview
What is the ICD-10 code for anencephaly?
The ICD-10-CM code for anencephaly is Q00.0 (sometimes written as Q000). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is Q00.0 (Anencephaly and similar malformations) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report anencephaly on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does Q00.0 group to?
When anencephaly is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 91, 92, 93, with relative weights from 0.7783 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.
Is Q00.0 a CC or MCC?
CMS lists Q00.0 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 3 closely related codes in its exclusion list.
Is Q00.0 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 anencephaly on inpatient claims. The code appears in the Congenital malformations of the nervous system (Q00-Q07) range of the CMS exempt list.
What HCC is Q00.0?
Q00.0 (anencephaly) maps to CMS-HCC Category 182 (Spinal Cord Disorders/Injuries), commonly written as HCC 182, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 72 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 155.
Does Q00.0 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, Q00.0 adds a risk adjustment factor of about 0.478 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.270 to 0.478 depending on the payment segment). A more severe related category (HCC 180, HCC 181, HCC 191, and HCC 192) supersedes it when both are reported. See the full factor table on the HCC 182 category page.
