Question: Our auditors have given us a list of unacceptable principal diagnosis codes. They want us to code what the principal diagnosis was for bringing the patient into the hospital. They are saying the following codes (and others) are not allowable as principal diagnosis codes based on CMS coding: O34.211 (Previous C-section scar), O32.1xx0 (Maternal care for breech presentation), and O36.5930 (IUFD). The list goes on, but my question is what in the world are we supposed to use? Someone within our group handling the refund requests from the auditor is telling us that if we aren’t using O80 or O82, then they are looking for complications of pregnancy codes O60-O77.9. So does that mean I have to use O65.5 for a schedule repeat c-section and O64.1 for a scheduled C-section for breech presentation? I’m unsure on how we would use an “obstruction of labor” code on scheduled C-sections where the patient never went into labor. Are we really calling a previous C-section or a previous myomectomy scar, obstructed labor? I have no clue what we are supposed to use for a patient who, for instance, has a fetal demise at 26 weeks and is scheduled for an induction, since apparently O36.5930 is an unacceptable principle diagnosis on the list as well. Fetal demise was the principal reason we sent her to the hospital to induce her. What else could we use here? Georgia Subscriber Answer: The instruction for the O34 codes is to “Code first any associated obstructed labor (O65.5).” This means if there is obstructed labor, you should code that as the principal diagnosis. If there is none, you can use just the O34 code. The O32 codes have no such “code first” instructions, but do indicate: “The appropriate code from category O30, Multiple gestation, must also be assigned when assigning a code from category O32 that has a 7th character of 1 through 9. (O30-O30.93, O32-O32.9xx9).” The O36.59 category also has no instruction about coding something first. Then, if you look at the ICD-10 guidelines on codes that cannot be used as a principal diagnosis, you get the following: “’In diseases classified elsewhere’ codes are never permitted to be used as first listed or principal diagnosis codes. They must be used in conjunction with an underlying condition code, and they must be listed following the underlying condition.” Ask your auditor to show you where it says this in the official ICD-10-CM guidelines, as there is only a small number of codes that cannot be specifically used as a principal diagnosis and the ones listed above (with the exception of the O34 codes) are not among them. If you comb the Chapter 15 section of the guidelines, which talk about how to use the codes, you will not see these codes mentioned either.