2026 ICD-10-CM Diagnosis Code O21.1Hyperemesis gravidarum with metabolic disturbance
ICD-10-CM Codes›O00-O9A›O20-O29›O21
- Billable — Valid for Submission
- Not Chronic
O21.1 is a billable ICD-10-CM diagnosis code for hyperemesis gravidarum with metabolic disturbance. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 817 through 819, 831 through 833. The code is restricted by the Medicare Code Editor to maternity cases (age 9 through 64). In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Other specified complications in pregnancy.
This medical diagnosis code is frequently used in OB/GYN medical specialties to designate conditions such maternal disorders related to pregnancy.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for O21.1.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Hyperemesis
- Hyperemesis gravidarum
- Hyperemesis gravidarum before end of 22 week gestation with carbohydrate depletion
- Hyperemesis gravidarum before end of 22 week gestation with dehydration
- Hyperemesis gravidarum before end of 22 week gestation with electrolyte imbalance
- Hyperemesis gravidarum with metabolic disturbance
- Severe hyperemesis gravidarum
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- Hyperemesis gravidarum, starting before the end of the 20th week of gestation, with metabolic disturbance such as carbohydrate depletion
- Hyperemesis gravidarum, starting before the end of the 20th week of gestation, with metabolic disturbance such as dehydration
- Hyperemesis gravidarum, starting before the end of the 20th week of gestation, with metabolic disturbance such as electrolyte imbalance
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
- Hyperemesis - R11.10
- with
- carbohydrate depletion - O21.1
- dehydration - O21.1
- electrolyte imbalance - O21.1
- metabolic disturbance - O21.1
- severe (with metabolic disturbance) - O21.1
- electrolyte - E87.8
- due to hyperemesis gravidarum - O21.1
External Cause of Injuries IndexGuidance
References for this code in the External Cause of Injuries Index.
- Hyperemesis
- gravidarum (mild)
- with
- carbohydrate depletion
- Hyperemesis
- gravidarum (mild)
- with
- dehydration
- Hyperemesis
- gravidarum (mild)
- with
- electrolyte imbalance
- Hyperemesis
- gravidarum (mild)
- with
- metabolic disturbance
- Hyperemesis
- gravidarum (mild)
- severe (with metabolic disturbance)
- Imbalance
- electrolyte
- due to hyperemesis gravidarum
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Hyperemesis Gravidarum
intractable vomiting that develops in early pregnancy and persists. this can lead to dehydration and weight loss.
Patient EducationClinical
Health Problems in Pregnancy
A health problem in pregnancy is any disease or condition that could affect your health or the health of your fetus. Some health problems may make it more likely that you will have a high-risk pregnancy. A high-risk pregnancy is one in which you, your fetus, or both are at higher risk for health problems than in a typical pregnancy.
The full article covers:
- What are health problems in pregnancy?
- What raises my risk for health problems during pregnancy?
- Can chronic health conditions cause problems in pregnancy?
- Can health problems in pregnancy be prevented?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert O21.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About O21.1Overview
Is O21.1 (Excessive vomiting in pregnancy) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report hyperemesis gravidarum with metabolic disturbance on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does O21.1 group to?
When hyperemesis gravidarum with metabolic disturbance is the principal diagnosis on an inpatient stay, it groups to MS-DRG 817, 818, 819, 831, 832, 833, with relative weights from 0.5229 to 1.6880 depending on complications. Higher weights mean higher Medicare reimbursement.
Who can O21.1 be reported for?
The Medicare Code Editor checks hyperemesis gravidarum with metabolic disturbance against patient demographics: this code is intended for maternity cases (age 9 through 64). Claims outside these limits are flagged as inconsistent.
What is the ICD-9 equivalent of O21.1?
Under the General Equivalence Mappings, hyperemesis gravidarum with metabolic disturbance converts to ICD-9-CM 643.13 (hyperem w metab-antepart). The mapping is approximate, so confirm the match fits the documentation.
Footnotes
[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.
