When is ICD-10 code O10.91 used?

Doctors, hospitals, and insurers may use ICD-10 code O10.91 when recording unspecified pre-existing hypertension complicating pregnancy in a standardized format. This entry may also act as a broader category that points toward more specific child codes.

Does ICD-10 code O10.91 confirm a diagnosis?

No. A code helps standardize documentation and claims, but it should not be read as a substitute for a clinician's full assessment.

ICD10

ICD-10 Code O10.91: Unspecified pre-existing hypertension complicating pregnancy

Name: ICD-10 Code O10.91: Unspecified pre-existing hypertension complicating pregnancy
Creator: HealthAssure Clinical Team
Published: 2026-05-21T06:27:26.993Z

O10.91 is an ICD-10 diagnosis entry used to group records related to Unspecified pre-existing hypertension complicating pregnancy. You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen. ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Pregnancy, childbirth and the puerperium (O00-O9A).

Reviewed by HealthAssure Clinical TeamUpdated 21 May 2026

What is this code?

ICD-10 entries help standardize how diagnoses are organized for coding, reporting, analytics, and documentation. This code sits within the broader ICD-10 area for Pregnancy, childbirth and the puerperium (O00-O9A).

When is it used?

May be used when a clinician documents unspecified pre-existing hypertension complicating pregnancy in a patient's medical record.
May appear in hospital records, claims, referrals, and clinical documentation.
This code may act more like a grouping or parent code, so a more specific child code may be used in final documentation when available.

What it does not mean

A code alone does not explain severity, treatment plan, or outcome.
A medical code should not be treated as a substitute for a doctor's diagnosis or advice.
This entry may represent a broader category rather than the most specific billable code.

Code hierarchy

chapter

15Pregnancy, childbirth and the puerperium (O00-O9A)

block

O10-O16Edema, proteinuria and hypertensive disorders in pregnancy, childbirth and the puerperium

Where you may see this code

You may see this entry in coding references, medical records, or claims workflows when a broader diagnosis category is being reviewed before a more specific code is chosen.

Related specialists

ObstetricianGynecologistCardiologistMaternal-Fetal Medicine Specialist

Related tests

Urine protein assessment

May be reviewed when evaluating hypertensive disorders in pregnancy.

Serum creatinine

Often reviewed when assessing kidney involvement in hypertensive disorders of pregnancy.

Platelet count

May be relevant when monitoring pregnancy-related hypertension complications.

Liver function tests

May be reviewed when hypertensive disorders in pregnancy raise concern for maternal complications.

Related procedures

Obstetric ultrasound

Commonly part of fetal growth and pregnancy follow-up pathways in hypertensive disorders of pregnancy.

Fetal nonstress testing

May be used in selected higher-risk pregnancy monitoring pathways.

Biophysical profile

May appear in fetal surveillance pathways for higher-risk pregnancies.

Sibling codes

O10.92Unspecified pre-existing hypertension complicating childbirthbillable O10.93Unspecified pre-existing hypertension complicating the puerperiumbillable

Coding guidelines

Common synonyms

Unspecified pre-existing hypertension complicating pregnancy

Frequently asked questions

About this content

This page is prepared by HealthAssure's clinical team using official coding standards from ICD-10. AI tools assist with drafting explanations, which are then reviewed and verified by healthcare professionals for accuracy. This content is for informational purposes and does not replace professional medical advice. Meet our team.