Updated on: November 28, 2016

The Most Important New Concepts in ICD-10-CM: A Recap

Original story posted on: September 21, 2015

As we head into the final stretch of ICD-10 preparations, it’s important to review the ICD-10-CM guidelines, some of which include significant changes that affect code completion/validity and sequencing. In fact, many of these changes are ripe for audit and compliance challenges. In this article, I’ve summarized some of the most pertinent ICD-10-CM guideline changes of which coders must be aware.

1. ICD-10-CM includes not one, but two types of excludes notes:

  • Excludes No. 1: Indicates “not coded here” – that is, that two conditions cannot be reported together. For example, abnormal coagulation profile (ICD-10-CM code R79.1) cannot be coded with hemophilia C (ICD-10-CM code D68.1).
  • Excludes No. 2: Indicates “not included here” – that is, that two conditions from different code categories may be reported together if both are present. For example, benign cyst of the breast (ICD-10-CM code N60.) may be coded with fibroadenoma of the breast (ICD-10-CM code D24.).

2. Some ICD-10-CM codes may require placeholder characters. These placeholders, denoted by the character “X,” allow for future code expansion without altering the character structure. For example, adverse effects of methadone, initial encounter (ICD-10-CM code T40.3X5A) requires a placeholder in the fifth-character position. Coders may miss these placeholders, given the variation in ICD-10-CM code length (i.e., codes can vary in length from three to seven alphanumeric characters). Always be on the lookout for when a placeholder may be necessary.

3. Certain ICD-10-CM code categories require seventh-character extensions. Pay close attention to the following:

  • Injuries, poisonings, and external causes: The seventh character provides information about the episode of care as follows:
    • Initial encounter (“A”) is defined as the period when a patient is receiving active treatment for an injury, poisoning, or other consequences of an external cause.
    • Subsequent encounter (“D”) is used when the encounter occurs after the active phase of treatment, when a patient is receiving routine care during a period of healing or recovery.
    • Sequela (“S”) is assigned for complications or conditions arising as a direct result of an injury.
  • All fractures: Generally, the seventh character provides information about the episode of care as well as whether the fracture is open or closed. During the healing phase, the seventh character specifies whether the healing is routine or with complications, such as delayed healing, nonunion, or malunion.
  • Certain types of open fractures: The seventh character provides additional information utilizing the Gustilo classification of open fractures (i.e., extent of tissue damaged and degree of bone injury or involvement).
  • Pregnancy, childbirth, and the puerperium: The seventh character provides information about the fetus, including:

    • Complications of pregnancy with multiple gestation to identify which fetus(es) is/are affected by the condition described by the code. A seventh character of “0” is used for single gestations.

If a code does not include six characters, use the placeholder “X” to fill the empty character(s) when a seventh-character value is required. For example, an unspecified fall, initial encounter requires three placeholders. Assign ICD-10-CM code W19.XXXA.

4. Many ICD-10-CM codes specify laterality (i.e., left, right, or bilateral). This is particularly true for injuries. If a patient has a bilateral condition, assign the bilateral code when one exists. Otherwise, assign separate codes for both the right and left sides.

Also note the ICD-10-CM guideline regarding dominant versus non-dominant sides for codes G81 (hemiplegia and hemiparesis), G83.1 (monoplegia of lower limb), G83.2 (monoplegia of upper limb), and G83.3 (monoplegia, unspecified). When a provider documents the affected side but not whether it is dominant or non-dominant, coders should make the following assumptions:

  • For ambidextrous patients, the default is dominant.
  • If the left side is affected, the default is non-dominant.
  • If the right side is affected, the default is dominant.

5. ICD-10-CM includes a new definition for subsequent acute myocardial infarction (AMI). In ICD-10-CM, a subsequent AMI is classified as one that occurs within four weeks of the initial MI. This differs from the eight-week timeframe in ICD-9-CM. A separate category in ICD-10-CM has been designated for this scenario (I22.).An I21 code must accompany an I22 code to identify the site of the initial AMI. The sequencing of the I22 and I21 depends on the circumstances of the admission.

Also new with ICD-10, category I21 may continue to be reported for transfers to not only other acute settings, but post-acute settings as long as the patient requires continued care for the myocardial infarction.

6. Certain ICD-10-CM obstetrics codes require additional information. Consider the following:

  • The majority of codes in Chapter 15 require a final character denoting the specific trimester of pregnancy.
  • When delivery occurs during the current admission and there is an “in-childbirth” option for the obstetric complication, assign the “in-childbirth” code.

7. ICD-10-CM includes many combination codes. A combination code is a single code that describes two diagnoses, a diagnosis with an associated manifestation, or a diagnosis with an associated complication. Be on the lookout for combination codes for the following:

  • Diabetic complications
  • Ulcers
  • Hypertensive heart and chronic kidney disease
  • Atherosclerotic coronary artery disease and angina
  • Injuries
  • External cause codes

Also note that combination codes for adverse effects, poisonings, under-dosing, and toxic effects include the substance taken as well as the intent.

8. ICD-10-CM includes a new guideline for coding anemia associated with malignancy. When the admission/encounter is for management of anemia associated with a malignancy but the patient only receives treatment for the anemia, sequence the malignancy as the principal diagnosis followed by an appropriate code for the anemia. Note that this is the exact opposite of the ICD-9 guideline for this same scenario.

9. The ICD-10-CM guidelines omit Section II, Guideline E pertaining to sequencing a symptom with contrasting/comparative diagnoses. This guideline states that when a symptom is followed by a contrasting/comparative diagnosis, the symptom is sequenced first, followed by all of the contrasting/comparative diagnoses. Coders have relied on this guideline in scenarios in which a physician hasn’t determined the exact or definitive etiology of a symptom for which treatment is rendered.

However, in ICD-10-CM, coders can’t report the symptom as the principal diagnosis in these scenarios. Instead, they must be guided by the other selection of Principal Diagnosis Guidelines noted in Section II. Potentially, with the deletion of Guideline E, there may be some open interpretation by auditors, particularly when the documentation is subpar.

By reviewing these guidelines, coders can ensure data integrity and increase efficiency. The encoder will help ensure compliance; however, coders also need to essentially memorize these guidelines, just as they have done in ICD-9-CM.


Disclaimer: Every reasonable effort was made to ensure the accuracy of this information at the time it was published. However, due to the nature of industry changes over time we cannot guarantee its validity after the year it was published.
Cathie Wilde, RHIA, CCS

Cathie Wilde, RHIA, CCS, is the director of coding services for MRA. Ms. Wilde has been active in the healthcare industry for more than 30 years. Her previous positions have included assistant director of HIM, DRG coordinator at the Massachusetts Hospital Association, and DRG validator at Blue Cross Blue Shield. She has extensive experience in ICD-9-CM and CPT coding, auditing, data analysis, development and testing of coding products, specialized reporting, and in-service training. As director she is responsible for overseeing the coding division, providing the strategic direction of MRA as a local industry leader of quality coding, auditing, and denial management services. Ms. Wilde is an American Health Information Management Association (AHIMA)-approved ICD-10-CM/PCS trainer.

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