2026 ICD-10-CM Diagnosis Code C56.1Malignant neoplasm of right ovary

ICD-10-CM Codes›C00–D49›C51-C58›C56

ICD-10-CM C56.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

C56.1 is a billable ICD-10-CM diagnosis code for malignant neoplasm of right ovary. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 736 through 741, 754 through 756. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Female reproductive system cancers - ovary.

Code Identity

ICD-10-CM Code
C56.1
Billable Status
Yes — Valid for Submission
Code Describes
Malignant neoplasm of right ovary
Short Description
Malignant neoplasm of right ovary
Same as the full description in the CMS dataset.
Parent Code
C56
Malignant neoplasm of ovary

Code Classification

ChapterC00–D49Neoplasms
SectionC51-C58Malignant neoplasms of female genital organs
CategoryC56Malignant neoplasm of ovary
This CodeC56.1Malignant neoplasm of right ovary

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Carcinosarcoma of bilateral ovaries
  • Carcinosarcoma of left ovary
  • Carcinosarcoma of ovary
  • Carcinosarcoma of right ovary
  • Carcinosarcoma of uterine adnexa
  • Cystadenocarcinoma of ovary
  • Endometrioid carcinoma ovary
  • Malignant germ cell neoplasm of right ovary
  • Malignant germ cell tumor of ovary
  • Malignant sex cord tumor of ovary
  • Malignant sex cord tumor of right ovary
  • Malignant tumor involving left ovary by direct extension from right ovary
  • Mucinous cystadenocarcinoma of ovary
  • Neoplasm of uncertain behavior of right ovary
  • Primary cystadenocarcinoma of ovary
  • Primary endometrioid carcinoma of ovary
  • Primary malignant neoplasm of both ovaries
  • Primary malignant neoplasm of left ovary
  • Primary malignant neoplasm of right ovary
  • Primary mucinous cystadenocarcinoma of ovary
  • Primary serous carcinoma of uterine adnexa
  • Primary serous papillary cystadenocarcinoma of right ovary
  • Primary serous papillary cystadenocarcinoma ovary
  • Right ovarian primary endometrioid carcinoma
  • Right ovarian primary mucinous cystadenocarcinoma
  • Right ovarian primary sarcoma
  • Right ovarian serous cystadenoma of borderline malignancy
  • Sarcoma of ovary
  • Serous cystadenoma borderline malignancy of ovary
  • Serous papillary cystadenocarcinoma ovary
  • Undifferentiated carcinoma of ovary
  • Undifferentiated carcinoma of right ovary

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR NEO033
Female reproductive system cancers - ovary
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Ovarian Cancer

Cancer is a disease in which abnormal cells in the body grow out of control and form a tumor. Ovarian cancer is a cancerous tumor that forms in the tissues of an ovary. The ovaries are a pair of female reproductive glands that make eggs and female hormones.

The full article covers:

  • What is ovarian cancer?
  • What are the types of ovarian cancer?
  • What causes ovarian cancer?
  • Who is more likely to develop ovarian cancer?
  • What are the symptoms of ovarian cancer?
  • How is ovarian cancer diagnosed?
  • What are the treatments for ovarian cancer?

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert C56.1 to ICD-9-CMHistory

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

ICD-9-CM
183.0 Malign neopl ovary
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 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About C56.1Overview

Is C56.1 (Malignant neoplasm of ovary) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report malignant neoplasm of right ovary on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does C56.1 group to?

When malignant neoplasm of right ovary is the principal diagnosis on an inpatient stay, it groups to MS-DRG 736, 737, 738, 739, 740, 741, 754, 755, 756, with relative weights from 0.9605 to 3.5745 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of C56.1?

Under the General Equivalence Mappings, malignant neoplasm of right ovary converts to ICD-9-CM 183.0 (malign neopl ovary). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.