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As the largest outsource coding provider in the country we have identified trends and gained unique insights from our coders throughout the transition to ICD-10.  We are sharing these insights with the broader HIM Community through our bi-weekly blog series “ICD-10 Quick Tips.” 

The subject matter for this series is currated based on the trending topics in our online question and answer system which services over 1,200 of our HIM professionals.  Our Subject Matter Experts have an average of 20 years of experience and are considered leaders in their field. 

This week’s post comes from National Compliance and Quality Audit Manager, Melissa McLeod, CDIP, CCDS, CCS, CPC, CPC-1, and AHIMA Approved ICD-10 Trainer. 

As promised in our last blog, today we are going to jump into some OB/GYN coding.  As always, it is important to start with the basics: in PCS coding, only procedures performed on the products of conception are included in the obstetrics section.  Procedures performed on a pregnant female other than the products of conception are coded to a root operation in the medical and surgical section of ICD-10-PCS.

Does that seem clear as mud?  It is actually not as complicated as it seems.  If you take a look in the ICD-10-PCS manual there are three pages in the obstetrics section dedicated to the topic, so it is not difficult to determine which chapter you should be using for coding.

Episode of Care

The episode of care is no longer a secondary axis (postpartum, antepartum, delivered); instead ICD-10-CM codes are identified by the trimester in which the condition occurred.  Assignment of the final character for trimester should be based on the provider’s documentation of the trimester (or 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.

Trimesters are calculated on completed weeks of gestation.

  • For example: 29 weeks and 6 days gestation is coded as 29 weeks gestation

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.

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.

Certain categories in Chapter 15 distinguish between conditions of the mother that existed prior to pregnancy (pre-existing) and those that are a direct result of pregnancy.  Categories that do not distinguish between pre-existing and pregnancy-related conditions may be used for either.  It is acceptable to use codes specifically for the puerperium with codes complicating pregnancy and childbirth if a condition arises postpartum during the delivery encounter.


It is the provider’s responsibility to state that the condition being treated is not affecting the pregnancy. Therefore, if not stated as incidental or affecting the pregnancy by the Provider, all conditions that occur when the patient is pregnant are complications of pregnancy.

The postpartum period begins immediately after delivery and continues for 6 weeks following delivery. Therefore, a postpartum complication is any complication occurring within the 6-week period.  The peripartum period is defined as the last month of pregnancy to 5 months postpartum.  Chapter 15 codes may also be used to describe pregnancy-related complications after the peripartum or postpartum period if the provider documents that a condition is pregnancy related.

Codes under subcategory O99.31, Alcohol use complicating pregnancy, childbirth, and the puerperium, should be assigned for any pregnancy case when a mother uses alcohol during the pregnancy or postpartum.  A secondary code from category F10, Alcohol related disorders, should also be assigned to identify manifestations of the alcohol use.  Similarly, codes under subcategory O99.33, Smoking (tobacco) complicating pregnancy, childbirth, and the puerperium, should be assigned for any pregnancy case when a mother uses any type of tobacco product during the pregnancy or postpartum.  A secondary code from category F17, Nicotine dependence, should also be assigned to identify the type of nicotine dependence.

  • The above guidelines direct you to code tobacco or alcohol use as a complication of pregnancy if these substances were used at all during the pregnancy…even if the patient quit 2 weeks into the pregnancy.

Postpartum Pre-ecclampsia: How is this coded without mention of pre-existing Pre-ecclampsia? Per EAB (Editorial Advisory Board) of Coding Clinic Feb.2016 through a correspondence from one of our Auditors.

  1. Assign Code O90.89 – Other complications of the puerperium, not elsewhere classified
  2. Assign Code I15.8 – Other secondary hypertension

Well that’s enough for this week…I hope you found some information in here that will help you as you continue your journey through the new world of ICD-10!

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