Top 10 ICD-10-CM Official Guideline Updates for 2020

The FY2020 ICD-10-CM Official Guidelines for Coding and Reporting (OGs) are available now so you can prepare for the 2020 diagnosis code changes and rule changes at the same time.

Some revisions involved adding a missing word that was already obvious from context, so we won’t cover every change here. But this overview will give you a good idea of the significant changes to come, effective Oct. 1, 2019.

1. Watch for Swap From ‘Physician’ to ‘Provider’

In a few places, the OGs replace “physician” with “provider.” All of the quotes below show the 2020 wording. The bold word shows where the 2019 OGs used the term physician instead of provider.

  • Section I.C.1.f, Zika virus infections: In 2020, the OGs state that, for Zika, “the provider’s diagnostic statement that the condition is confirmed is sufficient.”
  • Section I.C.17, Chapter 17: Congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99): The 2020 OGs state, “Whenever the condition is diagnosed by the provider, it is appropriate to assign a code from codes Q00-Q99.”
  • Section IV.G, ICD-10-CM code for the diagnosis, condition, problem, or other reason for encounter/visit: For this outpatient-specific section, the 2020 OGs state, “In some cases the first-listed diagnosis may be a symptom when a diagnosis has not been established (confirmed) by the provider.”

2. Update OGs in Line With 2020 MI Code Changes

ICD-10-CM 2020 makes an important change to coding for myocardial infarction (MI) type 2. In place of the 2019 instruction to “Code also the underlying cause, if known,” the new instruction for 2020 tells you to “Code first the underlying cause.” The 2020 OGs reflect this change, too, in Section I.C.9.e.5, which also sports a couple of other adjustments. The 2020 language is below with the changes marked in bold:

Type 2 myocardial infarction (myocardial infarction due to demand ischemia or secondary to ischemic imbalance) is assigned to code I21.A1, Myocardial infarction type 2 with the underlying cause coded first. Do not assign code I24.8, Other forms of acute ischemic heart disease, for the demand ischemia. If a type 2 AMI is described as NSTEMI or STEMI, only assign code I21.A1. Codes I21.01-I21.4 should only be assigned for type 1 AMIs.

3. Pick Up on ICD-10-CM OG Pressure Ulcer Changes

If you’ve been keeping tabs on what’s new in ICD-10-CM 2020, then you know there are new codes in the pressure ulcer category for pressure-induced deep tissue damage.

The 2020 OGs acknowledge this update with a few tweaks. Section I.C.12.a.1 references the new codes by adding the bold text: “The ICD-10-CM classifies pressure ulcer stages based on severity, which is designated by stages 1-4, deep tissue pressure injury, unspecified stage, and unstageable.”

The 2020 OGs also include an all new subsection at I.C.12.a.7:

7. Pressure-induced deep tissue damage

For pressure-induced deep tissue damage or deep tissue pressure injury, assign only the appropriate code for pressure-induced deep tissue damage (L89.–6).

4. Clarify Pregnancy Chapter Guidelines

Ob-gyn coders should check two areas of the 2020 OGs for small updates.

Section I.C.15.n replaces the term “perinatal” with “postnatal”: “Code O80 is always a principal diagnosis. It is not to be used if any other code from chapter 15 is needed to describe a current complication of the antenatal, delivery, or postnatal period.”

Section I.C.15.q.2 changes some wording regarding coding for complications. Here is the 2020 wording: “If the patient has a specific complication associated with the spontaneous abortion or elective termination of pregnancy in addition to retained products of conception, assign the appropriate complication code (e.g., O03.-, O04.-, O07.-) instead of code O03.4 or O07.4.”

The 2019 guideline is similar, but it says to “assign the appropriate complication in category O03 or O07,” with no reference to O04.-. The 2019 OGs also don’t make it clear that those categories are examples.

5. Add 2 New Guidelines for Injuries

Section I.C.19 covers guidelines for ICD-10-CM Chapter 19, which applies to injury codes. The 2020 OGs add two completely new subsections.

First is I.C.19.b.3, which covers iatrogenic injuries, meaning injuries from medical treatment:

3) Iatrogenic injuries

Injury codes from Chapter 19 should not be assigned for injuries that occur during, or as a result of, a medical intervention. Assign the appropriate complication code(s).

Second is I.C.19.c.3, about physeal (growth plate) fractures:

3) Physeal fractures

For physeal fractures, assign only the code identifying the type of physeal fracture. Do not assign a separate code to identify the specific bone that is fractured.

6. Make Room for New Multiple-Drug Codes and Rule

ICD-10-CM 2020 will add new subcategory T50.91- (Poisoning by, adverse effect of and underdosing of multiple unspecified drugs, medicaments and biological substances). The codes in that subcategory will be appropriate for multiple drug ingestion NOS, and you’ll choose among the codes based on intent, such as accidental or assault.

The 2020 OGs acknowledge the new subcategory by adding this language to I.C.19.e.4: “If multiple unspecified drugs, medicinal or biological substances were taken, assign the appropriate code from subcategory T50.91, Poisoning by, adverse effect of and underdosing of multiple unspecified drugs, medicaments and biological substances.”

7. Keep Complication Coding Clean

Section I.C.19.g.5, “Complications of care codes within the body system chapters,” gets a new paragraph in 2020 telling you to keep an eye out for T code alternatives:

Complication codes from the body system chapters should be assigned for intraoperative and postprocedural complications (e.g., the appropriate complication code from chapter 9 would be assigned for a vascular intraoperative or postprocedural complication) unless the complication is specifically indexed to a T code in chapter 19.

8. Blink and You’ll Miss the BMI Update

Section I.C.21.c.3 makes some small changes to the language for Z68.- body mass index codes (marked in bold below):

  • 2019: BMI codes should only be assigned when the associated diagnosis (such as overweight or obesity) meets the definition of a reportable diagnosis (see Section III, Reporting Additional Diagnoses).
  • 2020: BMI codes should only be assigned when there is an associated, reportable diagnosis (such as obesity).

9. Know When to Use New Travel Code Z71.84

When ICD-10-CM 2020 is effective, you’ll be able to report new code Z71.84 (Encounter for health counseling related to travel). A note with the code tells you it is appropriate for an “Encounter for health risk and safety counseling for (international) travel.”

The 2020 OGs add that you should use Z71.84 “for health risk and safety counseling for future travel purposes.” You’ll find that information in Section I.C.21.c.10.

10. Add More Certainty to ‘Uncertain Diagnosis’ Coding

The issue of how to code for probable diagnoses is a tricky one, especially because the rules are different for inpatient and outpatient coders. The 2020 OGs offer a little more term help.

For inpatient admissions to short-term, acute, long-term care, and psychiatric hospitals, Section II.H and Section III.C get identical updates with the addition of the bold terms:

If the diagnosis documented at the time of discharge is qualified as “probable,” “suspected,” “likely,” “questionable,” “possible,” or “still to be ruled out,” “compatible with,” “consistent with,” or other similar terms indicating uncertainty, code the condition as if it existed or was established.

Outpatient coders should check Section IV.H for the new bold terms:

Do not code diagnoses documented as “probable”, “suspected,” “questionable,” “rule out,” “compatible with,” “consistent with,” or “working diagnosis” or other similar terms indicating uncertainty.

These additions match advice in a 2005 AHA Coding Clinic (back when it was about ICD-9) that said terms such as “consistent with” and “compatible with” fall under the “uncertain diagnosis” category. If you’re looking for the source, it’s vol. 22, no. 3.

What About You?

Are there other areas in the ICD-10-CM official guidelines that you would like to see clarified?


Deborah works on a wide range of TCI SuperCoder projects, researching and writing about coding, as well as assisting with data updates and tool development for our online coding solutions. Since joining TCI in 2004, she’s covered the ins and outs of coding for radiology, cardiology, oncology and hematology, orthopedics, audiology, and more.

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