Q&A: Reporting BMI in ICD-10-CM for obstetrics patients

Q: A physician documented that a pregnant patient is obese, and the patient’s chart has a listed body mass index (BMI) score. Can we assign an ICD-10-CM BMI code in this instance or should this never be done for an obstetrics patient?

A: Interestingly, even though the physician may document that the patient is obese, based on the 2019 ICD-10-CM Official Guidelines for Coding and Reporting, BMI codes can’t be assigned for pregnant patients.

A code for obesity complicating pregnancy, found in ICD-10-CM subcategory O99.21- (obesity complicating pregnancy, childbirth, and the puerperium), should be assigned depending on the trimester of the encounter or if a delivery occurred during the encounter (in childbirth option). This would be accompanied by a code from category E66.- (obesity due to excess calories).

The ICD-10-CM manual does not include an Excludes1 note for fiscal year 2019 prohibiting the assignment of Z68.- (body mass index) codes with obesity complicating pregnancy (O99.21-), which makes it seem that we would lose the opportunity to classify the obesity as morbid.

Although morbidly obese patients may not be ideal candidates for pregnancy since, according to the American College of Obstetricians and Gynecologists, obesity puts patients at risk of several serious health problems, there are patients who would be classified as such prior to pregnancy and would be considered at higher risk for complications.

Editor’s note: This article originally appeared in JustCoding. Shannon McCall, RHIA, CCS, CCS-P, CPC, CEMC, CRC, CCDS, HCS-D, director of HIM and coding for HCPro in Middleton, Massachusetts, answered this question. Contact her at smccall@hcpro.com.