Health Information Management

Pregnancy coding: Understanding the differences between ICD-9-CM and ICD-10-CM

JustCoding News: Outpatient, July 25, 2012

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by Shelley C. Safian, PhD, CCS-P, CPC-H, CPC-I, AHIMA-approved ICD-10-CM/PCS trainer

As the transition to ICD-10-CM approaches, there has been a great deal of discussion about how much more information you will need to find your way through the thousands of additional codes. But as an educated professional coding specialist, you will discover that the differences between ICD-9-CM and ICD-10-CM will not create a major challenge for you.

Let’s take a look at some examples focusing on diagnosis codes reported for care provided to a pregnant woman. As you get the opportunity to investigate the complete chapter in ICD-10-CM, you will find that the additional information required is most assuredly already in the patient’s chart.

Prenatal visit coding
First, compare and contrast the code choices for a typical prenatal visit for a woman having a normal first pregnancy.

In ICD-9-CM, you would report V22.0 (supervision of normal first pregnancy).

ICD-10-CM gives you these four choices:
Z34.00, Encounter for supervision of normal first pregnancy, unspecified trimester
Z34.01, Encounter for supervision of normal first pregnancy, first trimester
Z34.02, Encounter for supervision of normal first pregnancy, second trimester
Z34.03, Encounter for supervision of normal first pregnancy, third trimester

The additional information that you will need to report this typical prenatal visit in ICD-10-CM is which trimester the patient is in during this encounter. Certainly, the attending physician is already including this detail in his or her encounter notes. You may not have noticed it until now because you didn’t need it to determine the correct code in ICD-9-CM.

If you are concerned about doing the math or the fact that some professionals may disagree on how many weeks are included in each trimester, don’t worry. ICD-10-CM clearly provides its definition at the very beginning of this chapter. It states, counted from the first day of the patient’s last menstrual period:

  • First trimester, less than 14 weeks 0 days
  • Second trimester, 14 weeks 0 days through less than 28 weeks 0 days
  • Third trimester, 28 weeks 0 days until delivery

As stated in the 2012 Official Guidelines for Coding and Reporting, coder should almost never report the code for unspecified trimester. To support a code with this description, you would need to prove that the attending physician could not possibly be reached for confirmation.

Coding for pregnancy complications
You will find, at times, ICD-10-CM actually reduces the number of codes you will need to report a complication or condition during pregnancy. Yes, combination codes, at times, will report the same information in one code rather than two codes required in ICD-9-CM. This patient is pregnant with twins (one placenta, one amniotic sac).

The ICD-9-CM coding looks like this:
651.03, Twin pregnancy, antepartum condition or complication
+ Use additional code to specify placenta status (V91.00–V91.99)
V91.00, Twin gestation, monochorionic/monoamniotic

Your ICD-10-CM choices are:
O30.011, Twin pregnancy, monochorionic/monoamniotic, first trimester
O30.012, Twin pregnancy, monochorionic/monoamniotic, second trimester
O30.013, Twin pregnancy, monochorionic/monoamniotic, third trimester
O30.019, Twin pregnancy, monochorionic/monoamniotic, unspecified trimester

Again, the only additional information required to code this patient’s encounter is the identification of which trimester she was in at this visit. At the very beginning of ICD-10-CM’s Chapter 15 Pregnancy, Childbirth, and the Puerperium (O00-O9A) is a notation applicable to every code in this chapter:
Use additional code from category Z3A (weeks of gestation) to identify the specific week of the pregnancy,

Therefore, when you are reporting circumstances for this patient from this section of ICD-10-CM, you need not only the trimester, but the specific week of gestation. The code choices in the Z3A code category begin with:

  • Z3A.01, Less than 8 weeks gestation of pregnancy
  • Z3A.08, 8 weeks gestation of pregnancy
  • Z3A.09, 9 weeks gestation of pregnancy

The codes increase one week at a time from there, all the way to:

  • Z3A.42, 42 weeks gestation of pregnancy
  • Z3A.49, Greater than 42 weeks gestation of pregnancy

Your physicians may not routinely document this very specific detail in their encounter notes; therefore you need to begin educating them now. Start looking for these details in your current notes to establish whether your physician must make an adjustment in documentation.
Should you find that even one physician doesn’t include the specific number of weeks of gestation, start urging the provider now to get in the habit of including it. By the time ICD-10-CM takes effect, every detail you need to determine the correct code will already be in the documentation—no query necessary.

Coding for eclampsia
This remains the same with the rest of Chapter 15 for pregnancy codes. Compare and contrast the reporting of a patient diagnosed with eclampsia (hypertension, convulsions, and proteinuria linked to the third-trimester of pregnancy). Even though this condition has not often been seen in patients earlier than the 28th week, ICD-10-CM provides a code to report eclampsia in the second trimester – just in case your patient has an unusual circumstance.

642.63, Eclampsia, antepartum condition or complication

O15.00, Eclampsia in pregnancy, unspecified trimester
O15.02, Eclampsia in pregnancy, second trimester
O15.03, Eclampsia in pregnancy, third trimester

Consistently, the only details you need to correctly report an ICD-10-CM code is to have the physician document the patient’s specific week of pregnancy when seen. From this, you will know which Z3A.0-code to use and you will be able to calculate the trimester, as well.

Official coding guidelines
When a pregnant patient is admitted into the hospital, her inpatient stay might cover two trimesters. The 2012 Official Guidelines for Coding and Reporting state that you should choose the code for the trimester in which the complication or condition first developed, not the trimester at discharge. If the complication was a pre-existing condition, having developed prior to this admission, then report the trimester at admission.

Some codes within this chapter require a seventh character to identify which fetus (in multiple gestations) is affected by the condition. For example, the physician is caring for a pregnant woman with the baby in breech presentation. You would report the appropriate seventh character from 1 through 5 to specify fetus 1, fetus 2, etc. The seventh character 0 (not applicable or unspecified) is used when the patient is carrying only one fetus or when the physician cannot determine which fetus is affected.

For example, Mary, pregnant with twins, is close to her due date and the physician noticed that fetus 2 is in breech position. Report code 032.1xx2 (maternal care for breech presentation, fetus 2).
Joan, pregnant with her first baby (single gestation), is ready to deliver but the baby is in breech position. Report 032.1xx0 (maternal care for breech presentation, not applicable).

NOTE: The fetus number is a seventh character. In this case, the actual code to report the care for breech position only has four characters, so you must insert an ‘x’ placeholder so that the fetus character lands in the seventh position.

Hopefully, this has provided you with some insights and eliminated any fears about reporting the care for a pregnant woman once ICD-10-CM takes effect. You can do this!

Shelley C. Safian, PhD, MAOM/HSM, CCS-P, CPC-H, CHA, of Safian Communications Services in Orlando, Fla., is a senior assistant professor who teaches medical billing and insurance coding at Herzing University Online in Milwaukee, Wis. Email her at

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