ICD-10-CM Guidelines for Coding and Reporting FY 2020 – Obstetrics

The Centers for Medicare and Medicaid Services (CMS) and the National Center for Health Statistics (NCHS), two departments within the U.S. Federal Government’s Department of Health and Human Services (DHHS) provide the guidelines for coding and reporting using the International Classification of Diseases, 10th Revision, Clinical Modification (ICD-10-CM). These guidelines should be used as a companion document to the official version of the ICD-10-CM.  These guidelines have been approved by the four organizations that make up the Cooperating Parties for the ICD-10-CM: the American Hospital Association (AHA), the American Health Information Management Association (AHIMA), CMS, and NCHS.

These guidelines are a set of rules that have been developed to accompany and complement the official conventions and instructions provided within the ICD-10-CM itself. The instructions and conventions of the classification take precedence over guidelines. These guidelines are based on the coding and sequencing instructions in the Tabular List and Alphabetic Index of ICD-10-CM but provide additional instruction. Adherence to these guidelines when assigning ICD-10-CM diagnosis codes is required under the Health Insurance Portability and Accountability Act (HIPAA).

These guidelines have been developed to assist both the healthcare provider and the coder in identifying those diagnoses that are to be reported. The importance of consistent, complete documentation in the medical record cannot be overemphasized. Without such documentation, accurate coding cannot be achieved. The entire record should be reviewed to determine the specific reason for the encounter and the conditions treated. In addition to general coding guidelines, there are guidelines for specific diagnoses and/or conditions in the classification.

General Rules for Obstetric Cases

Codes from chapter 15 and sequencing priority

Obstetric cases require codes in the range O00-O9A, Pregnancy, Childbirth, and the Puerperium. These codes have sequencing priority over codes.  Additional codes from other chapters may be used in conjunction with O00-O9A codes to further specify conditions. Should the provider document that the pregnancy is incidental to the encounter, then code Z33.1, Pregnant state, incidental, should be used in place of any O00-O9A codes. It is the provider’s responsibility to state that the condition being treated is not affecting the pregnancy.

Final character for trimester

The majority of codes in Pregnancy, Childbirth, and the Puerperium (O00-O9A) have a final character indicating the trimester of pregnancy. If trimester is not a component of code, it is because the condition always occurs in a specific trimester, or the concept of the trimester of pregnancy is not applicable. Certain codes have characters for only certain trimesters because the condition does not occur in all trimesters, but it may occur in more than just one.

The assignment of the final character for trimester should be based on the provider’s documentation of the trimester (or the number of weeks) for the current admission/encounter. This applies to the assignment of trimester for pre-existing conditions as well as those that develop during or are due to the pregnancy. The provider’s documentation of the number of weeks may be used to assign the appropriate code identifying the trimester. Whenever delivery occurs during the current admission, and there is an “in childbirth” option for the obstetric complication being coded, the “in childbirth” code should be assigned.

Selection of trimester for inpatient admissions that encompass more than one trimester

In instances when a patient is admitted to a hospital for complications of pregnancy during one trimester and remains in the hospital into a subsequent trimester, the trimester character for the antepartum complication code should be assigned on the basis of the trimester when the complication developed, not the trimester of the discharge. If the condition developed prior to the current admission/encounter or represents a pre-existing condition, the trimester character for the trimester at the time of the admission/encounter should be assigned.

Unspecified trimester

Each category that includes codes for trimester has a code for “unspecified trimester.” The “unspecified trimester” code should rarely be used, such as when the documentation in the record is insufficient to determine the trimester and it is not possible to obtain clarification.

7th character for Fetus Identification

Where applicable, a 7th character is to be assigned for certain categories (O31, O32, O33.3 – O33.6, O35, O36, O40, O41, O60.1, O60.2, O64, and O69) to identify the fetus for which the complication code applies. Assign 7th character “0”:

    • For single gestations
    • When the documentation in the record is insufficient to determine the fetus affected and it is not possible to obtain clarification.
    • When it is not possible to clinically determine which fetus is affected.

In fee-for-service medicine, physician services are paid based on the fee associated with the CPT or HCPCS code submitted on the claim form. The diagnosis code supports the medical necessity for the service and tells the payer why the service was performed. It can be the source of denial if it doesn’t show the medical necessity for the service performed.

Diagnostic and procedural codes are connected to nearly every system and business process in health plans and provider organizations, including reimbursement and claim processes. For smoother claim processing and reduced denials, equal attention to diagnosis coding is important. Medical Billers and Coders (MBC) systematically connects diagnosis and procedural codes ensuring timely payments from insurance carriers. To know more about our medical coding and billing services you contact us at 888-357-3226/info@medicalbillersandcoders.com


International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM)