How to Code Renal Disease in Pregnancy

The following is a summary of two segments during the live broadcast of Talk Ten Tuesdays on Jan. 30, 2018 featuring program co-host Erica Remer, MD, FACEP, CCDS and Linda Holtzman, MHA, RHIA, CCS, CCS-P, CPC, COC.

Dr. Erica Remer:

I believe coding is as much an art as a science as medicine is. Sometimes, there is a right answer. Sometimes there is a gray zone and room for interpretation by the coder. Some conditions are approached differently in ICD-10 compared to ICD-9. And sometimes there is a point of confusion which may best be resolved by a change in the guidelines or a Coding Clinic.

Last year, I did a set of obstetrics webinars. I always offer the disclaimer that I am not a coder or a CDIS, but I just play one on the internet. I also should disclose that the majority of my coding experience has been in ICD-10.

In December, Jodi Kingley, a coder with over four years experience, watched the webcast on demand, and she contacted me and asked me for clarification about renal disease in pregnancy.

When I prepare for webinars or education, I do extensive research, but I am not infallible. I played with the 3M encoder and it seemed to send me to O26.8- which seem to be confirmed when I looked at the alphabetic index.


I just thought this was a quirk of ICD-10 because I was incredulous that there could be specificity for anemia, hematologic and immunologic disorders, endocrine disease, substance abuse, diseases of the nervous, respiratory, digestive, and circulatory systems, but not for renal disease. After all, the title of O26 subcategory was Maternal care for other conditions PREDOMINANTLY related to pregnancy.

But Jodi pointed out that the name of this particular code was “Pregnancy related renal disease” which indicated to her that it is intended to capture renal disease related specifically to the pregnancy.

I searched the internet for the definitive answer, but couldn’t find it, so I conceded and went to my go-to expert, Linda Holtzman.

Some of you may have heard me tell you that participating in the ICD-10 Coordination and Maintenance Committee meetings is one of the most exciting and fun activities I do all year. I feel like I am really contributing, like I am being a change agent. This is how I met Linda, who currently works as the principal for Clarity Coding. Linda makes many comments I was thinking and I found her to be very practical and insightful. I asked her to resolve this issue for me, and for you: Is pre-existing renal disease complicating a pregnancy coded with O26.8- or O99.89, Other specified diseases and conditions complicating pregnancy, childbirth, and the puerperium.

Here is what she had to say.

Linda Holtzman, MHA, RHIA, CCS, CCS-P, CPC, COC:

My first thought was I’d like to be in option D and never have to code obstetrical conditions. I can understand how you were confused, but, as a coding auditor, I can tell you that encoders are not infallible either.

The correct answer is actually B. For the example you provided me (ESRD at 22 weeks of pregnancy), you would use code O99.89, Other specified diseases and conditions complicating pregnancy, plus N18.6 for ESRD and Z3A.22 for the weeks of gestation.

The issue, of course, is what is the difference between category O26 for ‘other conditions predominantly related to pregnancy’ versus category O99 for ‘other maternal diseases classifiable elsewhere but complicating pregnancy?’ Here’s the rule of thumb: codes in category O26 are generally for obstetrical conditions complicating the pregnancy, like diseases that result from pregnancy or are intrinsically linked to pregnancy. In contrast, codes in category O99 are for non-obstetrical conditions that complicate the pregnancy, like pre-existing disorders or non-pregnancy-related conditions that arise during the pregnancy and complicate it.

For example, we see that category O26 classifies conditions like low weight gain in pregnancy, herpes gestationis, subluxation of the pubis in pregnancy, pregnancy related exhaustion, and spotting in pregnancy. These are all inextricably associated with being pregnant. Now look to category O99. That classifies conditions like anemia in pregnancy (and various exclusion notes within ICD-10 make clear this includes pre-existing anemia); alcohol and drug use, and mental disorders, also generally pre-existing;strep B colonization which naturally occurs in the vagina in many women; and other similar conditions that are “classifiable elsewhere.” They’re “classifiable elsewhere” because people get them all the time, pregnant or not. This O code signifies that it’s a complication for a particular patient who happens to be pregnant. They generally require a second code to supply the detail of the specific diagnosis.

Perhaps a good example of the distinction is that pregnancy complicated by cholestasis is O26.6 but pregnancy complicated by cholecystitis is O99.6. These are both biliary tract disorders. But “cholestasis of pregnancy” is a specific condition caused by hormonal effects on bile flow during pregnancy, whereas cholecystitis can happen to any patient, pregnant or not. Likewise, excessive weight gain in pregnancy, is classified to O26 and is associated specifically with being pregnant, while obesity which is complicating pregnancy is classified to O99, because obesity is pre-existing.

The next question is: well, how would we know this? ICD-10 doesn’t make it easy! There are exceptions and inconsistencies; it’s maddening. But there is some guidance. The AHA’s ICD-10-CM Coding Handbook, published by the team behind Coding Clinic, contains examples such as multiple sclerosis, a pre-existing condition, coded to O99.35, diseases of the nervous system complicating pregnancy. The instructional notes for category O99 are another clue. Under O99.5, diseases of the respiratory system complicating pregnancy, there’s a note which says, “Conditions in J00-J99.” That’s one way to know that pneumonia, J18.9 is coded to O99.5 when the patient is pregnant. Under O99.8, there’s a note that says, “Conditions in … M00-N99 …”. ESRD is N18.6 so it seems like that belongs here under O99.8.

What kinds of renal conditions go to O26.83? According to the Index, it’s conditions such as nephritis, glomerular disease, and nephropathy, also generic uremia in pregnancy. The Index does list O26.83 for pregnancy complicated by renal disease or failure but it’s for renal disease or failure Not Elsewhere Classified.

And for coding old-timers, it’s worth noting that there was a similar distinction in ICD-9 and we could see that, with some adjustments, much of that convention carried over into ICD-10.

If it helps, struggling with use of O26 versus O99 for a pregnant patient with ESRD is probably more of a theoretical coding issue than a practical one. That’s because the main causes of ESRD are diabetes and hypertension, and there are clear coding instructions in those scenarios.

First, based on the Official Coding Guidelines as well as how the conditions are indexed, we are permitted to assume a cause-and-effect relationship between diabetes and chronic kidney disease, and between hypertension and chronic kidney disease, even if the physician doesn’t explicitly document a link.

ESRD in type 1 diabetes in pregnancy is coded O24.01-, pre-existing type 1 diabetes mellitus in pregnancy. There’s an instructional note with O24.01 that says to “use additional code from category E10 to further identify any manifestations”. To add the specificity, we add E10.22, type 1 diabetes with diabetic chronic kidney disease and, following another “use additional code” note there, N18.6 for ESRD.

It’s similar for hypertensive ESRD in pregnancy. Use code O10.21-, Pre-existing hypertensive chronic kidney disease complicating pregnancy, and then follow the “use additional code” note to add I12.0, Hypertensive chronic kidney disease with stage 5 chronic kidney disease or end stage renal disease, pus N18.6.

Those two coding scenarios should take care of the vast majority of cases for ESRD affecting a pregnancy. Perhaps this is why ICD-10-CM doesn’t have specific notes or indexing for ESRD in pregnancy. Nonetheless, the general distinction between O26 and O99 is still an area of confusion. Perhaps a proposal for the ICD-10 Coordination and Maintenance Committee to add instructional notes to the Tabular and to add entries to the Index to make the distinction between O26 and O99 more clear is in order. We’ll keep you posted!

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