Coding for Obstetrical Services in ICD-10 requires additional information over what was necessary for coding in ICD-9. The majority of codes in the Obstetrics Chapter include a character, either in the 6th position or final position, to identify the trimester or number of weeks of pregnancy. Each category that involves the use of a digit for “trimester” includes a code for “unspecified trimester,” but this should rarely be reported because the documentation should indicate the trimester involved, per the coding guidelines in ICD-10.

The following is an example of how the trimester determines the ICD-10 that’s reported:

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Per the ICD-10 chapter 15 (15.a.3) guidelines, the trimester timeframes are as follows:

  • 1st Trimester – less than 14 weeks, 0 days
  • 2nd Trimester – 14 weeks 0 days to less than 28 weeks 0 days
  • 3rd Trimester – 28 weeks 0 days to delivery
  • Weeks of Gestation (appended to certain codes from another chapter)

In addition to the trimester in the above example, a 7th character will need assigned to describe the fetus involved:

  • 0=not applicable or unspecified
  • 1=fetus 1
  • 2=fetus 2
  • 3=fetus 3
  • 4=fetus 4
  • 5=fetus 5
  • 9=other fetus

This change is applicable to categories O31, O32, O33.3-O33.6, O35, O36, O40, O41, O60.1, O60.2, O64 and O69, and is used to identify the fetus for which the complication code applies.

When there is an obstetrical encounter where no delivery occurs, “the primary diagnosis should correspond to the complication of the pregnancy which prompted the encounter.” For example, an obstetrical patient in her first trimester is admitted for a cervical cerclage for incompetent cervix.

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When there is a cesarean delivery, “the primary diagnosis code should be the condition that is established as responsible for the patient’s admission.”

  • “If the patient was admitted with a condition that resulted in the performance of a cesarean procedure, that condition should be selected as the principal diagnosis.”
  • “If the reason for the admission/encounter was unrelated to the condition resulting in the cesarean delivery, the condition related to the reason for the admission/encounter should be selected as the principal diagnosis.”

“The outcome of the delivery also should be included on every maternal record when a delivery has occurred” according to chapter 15. 5. There has also been a change to the timeframe for missed abortion from 22 weeks in ICD-9 to 20 weeks in ICD-10.

American Medical Association, The Complete Official Draft Codebook ICD-10-CM, Chapter 15.

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Mary Jo Gross, CPC, CANPC of Compliance – Anesthesia and Pain Management, web2pro Business Performance Services