2025 ICD-10-CM Diagnosis Code O21.2

Approximate Synonyms

The following list of clinical terms are approximate synonyms, alternative descriptions, or common phrases that might be used by patients, healthcare providers, or medical coders to describe the same condition. These synonyms and related diagnosis terms are often used when searching for an ICD-10 code, especially when the exact medical terminology is unclear. Whether you're looking for lay terms, similar diagnosis names, or common language alternatives, this list can help guide you to the correct ICD-10 classification.

Clinical Classification

Clinical Classifications group individual ICD-10-CM diagnosis codes into broader, clinically meaningful categories. These categories help simplify complex data by organizing related conditions under common clinical themes.

They are especially useful for data analysis, reporting, and clinical decision-making. Even when diagnosis codes differ, similar conditions can be grouped together based on their clinical relevance. Each category is assigned a unique CCSR code that represents a specific clinical concept, often tied to a body system or medical specialty.

Code Edits

The Medicare Code Editor (MCE) detects errors and inconsistencies in ICD-10-CM diagnosis coding that can affect Medicare claim validity. These Medicare code edits help medical coders and billing professionals determine when a diagnosis code is not appropriate as a principal diagnosis, does not meet coverage criteria. Use this list to verify whether a code is valid for Medicare billing and to avoid claim rejections or denials due to diagnosis coding issues.

MS-DRG Mapping for ICD-10-CM Code O21.2

Diagnosis-Related Groups (DRGs) are used to classify hospital cases for billing and healthcare management. They help standardize how hospitals and other providers are reimbursed for inpatient care. Patients are grouped based on their principal diagnosis into broader categories called Major Diagnostic Categories (MDCs).

Once assigned to a DRG, the hospital receives a set payment for the patient’s care, regardless of the actual services provided. This fixed rate is intended to cover the typical cost of treating patients within that group. The payment amount depends on the DRG's relative weight, which reflects the expected complexity and cost of care based on the severity of the patient’s condition.

Diagnostic related groups encourage healthcare providers to focus on quality and efficiency in patient care while managing costs effectively. The diagnosis code is present in the following groups for version MS-DRG V42.0 applicable from 10/01/2024 through 09/30/2025.

Convert O21.2 to ICD-9-CM

Below are the ICD-9 codes that most closely match this ICD-10 code, based on the General Equivalence Mappings (GEMs). This ICD-10 to ICD-9 crosswalk tool is helpful for coders who need to reference legacy diagnosis codes for audits, historical claims, or approximate code comparisons.

Patient Education

Health Problems in Pregnancy

Every pregnancy has some risk of problems, but there are certain conditions and health issues that can raise that risk, such as:

• A health condition you had before you got pregnant
• A health condition you develop during pregnancy
• A pregnancy with more than one baby
• A health problem that happened during a previous pregnancy and could happen again
• Substance use during pregnancy
• Being over age 35

Any of these can affect your health, the health of your baby, or both.

If you have a chronic condition, you should talk to your health care provider about how to minimize your risk before you get pregnant. Once you are pregnant, you may need a health care team to monitor your pregnancy. Some common conditions that can complicate a pregnancy include:

• High blood pressure
• Kidney problems
• Autoimmune diseases
• Obesity
• HIV
• Cancer
• Infections

Other conditions that may make pregnancy risky can develop during pregnancy - for example, gestational diabetes and Rh incompatibility. Good prenatal care can help detect and treat them.

Some symptoms, such as nausea, back pain, and fatigue, are common during pregnancy. Sometimes it is hard to know what is normal. Call your health care provider if something is bothering or worrying you.

[Learn More in MedlinePlus]

Nausea and Vomiting

What are nausea and vomiting?

Nausea is when you feel sick to your stomach, as if you are going to throw up. Vomiting is when you throw up.

What causes nausea and vomiting?

Nausea and vomiting can be symptoms of many different conditions, including:

• Morning sickness during pregnancy
• Gastroenteritis (infection of your intestines) and other infections
• Migraines
• Motion sickness
• Food poisoning
• Medicines, including those for cancer chemotherapy
• GERD (reflux) and ulcers
• Intestinal obstruction

When do I need to see a health care provider for nausea and vomiting?

Nausea and vomiting are common. They are usually not serious. However, you should contact your health care provider immediately if you have:

• A reason to think that your vomiting is from poisoning
• Vomited for longer than 24 hours
• Blood in the vomit
• Severe abdominal pain
• Severe headache and stiff neck
• Signs of dehydration, such as dry mouth, infrequent urination or dark urine

How is the cause of nausea and vomiting diagnosed?

Your health care provider will take your medical history, ask about your symptoms and do a physical exam. The provider will look for signs of dehydration. You may have some tests, including blood and urine tests. Women may also have a pregnancy test.

What are the treatments for nausea and vomiting?

Treatments for nausea and vomiting depend on the cause. You may get treatment for the underlying problem. There are some medicines that can treatment nausea and vomiting. For severe cases of vomiting, you may need extra fluids through an IV (intravenous).

There are things that you can do to feel better:

• Get enough fluids, to avoid dehydration. If you are having trouble keeping liquids down, drink small amounts of clear liquids often.
• Eat bland foods; stay away from spicy, fatty, or salty foods
• Eat smaller meals more often
• Avoid strong smells, since they can sometimes trigger nausea and vomiting
• If you are pregnant and have morning sickness, eat crackers before you get out of bed in the morning

[Learn More in MedlinePlus]

Code History

• FY 2024 - No Change, effective from 10/1/2023 through 9/30/2024
• FY 2023 - No Change, effective from 10/1/2022 through 9/30/2023
• FY 2022 - No Change, effective from 10/1/2021 through 9/30/2022
• FY 2021 - No Change, effective from 10/1/2020 through 9/30/2021
• FY 2020 - No Change, effective from 10/1/2019 through 9/30/2020
• FY 2019 - No Change, effective from 10/1/2018 through 9/30/2019
• FY 2018 - No Change, effective from 10/1/2017 through 9/30/2018
• FY 2017 - No Change, effective from 10/1/2016 through 9/30/2017
• FY 2016 - New Code, effective from 10/1/2015 through 9/30/2016. This was the first year ICD-10-CM was implemented into the HIPAA code set.