Take Note of the 2018 ICD-10-CM Official Guidelines

Review the new guidelines to ensure clinician documentation supports diagnosis coding.

The 2018 ICD-10-CM Official Guidelines for Coding and Reporting includes a dozen substantive changes in Section I, and one important change in Section II. Here are those changes.

Section I Key Changes

1. Information has been added to clarify the meaning of “with” (new text is bold):
The word “with” or “in” should be interpreted to mean “associated with” or “due to” when it appears in a code title, the Alphabetic Index, or an instructional note in the Tabular List. The classification presumes a causal relationship between the two conditions linked by these terms in the Alphabetic Index or Tabular List. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated or when another guideline exists that specifically requires a documented linkage between two conditions (e.g., sepsis guideline for “acute organ dysfunction that is not clearly associated with the sepsis”).
For conditions not specifically linked by these relational terms in the classification or when a guideline requires that a linkage between two conditions be explicitly documented, provider documentation must link the conditions to code them as related.
2. “Code also” guidelines are clarified. When two codes may be required to fully describe a condition, a “code also” note is indicated. The note does not provide sequencing direction. The new guidelines explain, “The sequencing depends on the circumstances of the encounter.”
3. Information is added for brachytherapy, within admissions/encounters involving chemotherapy, immunotherapy, and radiation therapy:
If a patient admission/encounter is solely for the administration of chemotherapy, immunotherapy or external beam radiation therapy,  assign code Z51.0, Encounter for antineoplastic radiation therapy, or Z51.11, Encounter for antineoplastic chemotherapy, or Z51.12, Encounter for antineoplastic immunotherapy as the first-listed or principal diagnosis. If a patient receives more than one of these therapies during the same admission more than one of these codes may be assigned, in any sequence.
The malignancy for which the therapy is being administered should be assigned as a secondary diagnosis.
If a patient admission/encounter is for the insertion or implantation of radioactive elements (e.g., brachytherapy) the appropriate code for the malignancy is sequenced as the principal or first-listed diagnosis. Code Z51.0 should not be assigned. 
3) Patient admitted for radiation therapy, chemotherapy or immunotherapy and develops complications
When a patient is admitted for the purpose of external beam radiotherapy, immunotherapy or chemotherapy and develops complications such as uncontrolled nausea and vomiting or dehydration, the principal or first-listed diagnosis is Z51.0, Encounter for antineoplastic radiation therapy, or Z51.11, Encounter for antineoplastic chemotherapy, or Z51.12, Encounter for antineoplastic immunotherapy followed by any codes for the complications.
When a patient is admitted for the purpose of insertion or implantation of radioactive elements (e.g., brachytherapy) and develops complications such as uncontrolled nausea and vomiting or dehydration, the principal or first-listed diagnosis is the appropriate code for the malignancy followed by any codes for the complications.
4. Coding for diabetes with the use of insulin or oral diabetic medication is clarified:
Diabetes mellitus and the use of insulin and oral hypoglycemics 
If the documentation in a medical record does not indicate the type of diabetes but does indicate that the patient uses insulin, code E11-, Type 2 diabetes mellitus, should be assigned. An additional code should be assigned from category Z79 to identify the long-term (current) use of insulin or oral hypoglycemic drugs. If the patient is treated with both oral medications and insulin, only the code for long-term (current) use of insulin should be assigned. Code Z79.4 should not be assigned if insulin is given temporarily to bring a type 2 patient’s blood sugar under control during an encounter. 
Secondary diabetes mellitus 
Codes under categories E08, Diabetes mellitus due to underlying condition, E09, Drug or chemical induced diabetes mellitus, and E13, Other specified diabetes mellitus, identify complications/manifestations associated with secondary diabetes mellitus. Secondary diabetes is always caused by another condition or event (e.g., cystic fibrosis, malignant neoplasm of pancreas, pancreatectomy, adverse effect of drug, or poisoning).
(a) Secondary diabetes mellitus and the use of insulin or oral hypoglycemic drugs 
For patients with secondary diabetes mellitus who routinely use insulin or oral hypoglycemic drugs, an additional code from category Z79 should be assigned to identify the long-term (current) use of insulin or oral hypoglycemic drugs. If the patient is treated with both oral medications and insulin, only the code for long-term (current) use of insulin should be assigned. Code Z79.4 should not be assigned if insulin is given temporarily to bring a type 2 patient’s blood sugar under control during an encounter. 
5. Guidelines are added for mental and behavioral disorders due to psychoactive substance use, in remission:
Selection of codes for “in remission” for categories F10-F19, Mental and behavioral disorders due to psychoactive substance use (categories F10-F19 with -11, -.21) requires the provider’s clinical judgment. The appropriate codes for “in remission” are assigned only on the basis of provider documentation (as defined in the Official Guidelines for Coding and Reporting), unless otherwise instructed by the classification. 
Mild substance use disorders in early or sustained remission are classified to the appropriate codes for substance abuse in remission, and moderate or severe substance use disorders in early or sustained remission are classified to the appropriate codes for substance dependence in remission. 
6. There are new guidelines for blindness. When “blindness” or “low vision” in both eyes is documented, but the visual impairment category is not documented, use code H54.3 Unqualified visual loss, both eyes. When “blindness” or “low vision” is documented in one eye, but the visual impairment category is not documented, report a code from H54.6- Unqualified visual loss, one eye. When “blindness” or “visual loss” is documented without information specifying one or both eyes are affected, choose code H54.7 Unspecified visual loss.
7. New guidelines are added for pulmonary hypertension. Pulmonary hypertension is classified to category I27 Other pulmonary heart diseases. For secondary pulmonary hypertension (I27.1 Kyphoscoliotic heart disease, I27.2- Other secondary pulmonary hypertension), code also associated conditions or adverse effects of drugs or toxins. Base sequencing on the reason for the encounter.
8. Guidelines for acute myocardial infarction (AMI) are revised, specifying “type 1” AMI, where required and guidelines are added for other types of MI:
1) Type 1 ST elevation myocardial infarction (STEMI) and non-ST elevation myocardial infarction (NSTEMI) 
The ICD-10-CM codes for type 1 acute myocardial infarction (AMI) identify the site, such as anterolateral wall or true posterior wall. Subcategories I21.0-I21.2 and code I21.3 are used for type 1 ST elevation myocardial infarction (STEMI). Code I21.4, Non-ST elevation (NSTEMI) myocardial infarction, is used for type 1 non ST elevation myocardial infarction (NSTEMI) and nontransmural MIs.
If a type 1 NSTEMI evolves to STEMI, assign the STEMI code. If a type 1 STEMI converts to NSTEMI due to thrombolytic therapy, it is still coded as STEMI.
2) Acute myocardial infarction, unspecified 
Code I21.9, Acute myocardial infarction, unspecified, is the default for unspecified acute myocardial infarction or unspecified type. If only type 1 STEMI or transmural MI without the site is documented, assign code I21.3, ST elevation (STEMI) myocardial infarction of unspecified site.
3) AMI documented as nontransmural or subendocardial but site provided
If an AMI is documented as nontransmural or subendocardial, but the site is provided, it is still coded as a subendocardial AMI.
See Section I.C.21.3 for information on coding status post administration of tPA in a different facility within the last 24 hours. 
4) Subsequent acute myocardial infarction
A code from category I22, Subsequent ST elevation (STEMI) and non-ST elevation (NSTEMI) myocardial infarction, is to be used when a patient who has suffered a type 1 or unspecified AMI has a new AMI within the 4 week time frame of the initial AMI. A code from category I22 must be used in conjunction with a code from category I21. The sequencing of the I22 and I21 codes depends on the circumstances of the encounter.
Do not assign code I22 for subsequent myocardial infarctions other than type 1 or unspecified. For subsequent type 2 AMI assign only code I21.A1. For subsequent type 4 or type 5 AMI, assign only code I21.A9.
5) Other Types of Myocardial Infarction
The ICD-10-CM provides codes for different types of myocardial infarction. Type 1 myocardial infarctions are assigned to codes I21.0-I21.4. 
Type 2 myocardial infarction, and myocardial infarction due to demand ischemia or secondary to ischemic balance, is assigned to code I21.A1, Myocardial infarction type 2 with a code for the underlying cause. Do not assign code I24.8, Other forms of acute ischemic heart disease for the demand ischemia. Sequencing of type 2 AMI or the underlying cause is dependent on the circumstances of admission. When a type 2 AMI code is described as NSTEMI or STEMI, only assign code I21.A1. Codes I21.01-I21.4 should only be assigned for type 1 AMIs. 
Acute myocardial infarctions type 3, 4a, 4b, 4c and 5 are assigned to code I21.A9, Other myocardial infarction type. 
The “Code also” and “Code first” notes should be followed related to complications, and for coding of postprocedural myocardial infarctions during or following cardiac surgery. 
9. New guidelines are introduced for non-pressure chronic ulcers. For admitted patients with non-pressure ulcers, do not assign a code if the documentation says the non-pressure ulcer is completely “healed.” For admitted patients with non-pressure ulcers documented as “healing,” new guidelines say:
Non-pressure ulcers described as healing should be assigned the appropriate non-pressure ulcer code based on the documentation in the medical record. If the documentation does not provide information about the severity of the healing non-pressure ulcer, assign the appropriate code for unspecified severity. 
If the documentation is unclear as to whether the patient has a current (new) non-pressure ulcer or if the patient is being treated for a healing non-pressure ulcer, query the provider. 
For ulcers that were present on admission but healed at the time of discharge, assign the code for the site and severity of the non-pressure ulcer at the time of admission. 
For admitted patients with a non-pressure ulcer that progresses to a higher severity level during the admission, use two separate codes, “one code for the site and severity level of the ulcer on admission and a second code for the same ulcer site and the highest severity level reported during the stay.”
10. New and revised instruction are introduced regarding retained products of conception following an abortion:
Subsequent encounters for retained products of conception following a spontaneous abortion or elective termination of pregnancy, without complications are assigned O03.4, Incomplete spontaneous, abortion without complication, or codes O07.4, Failed attempted termination of pregnancy without complication. This advice is appropriate even when the patient was discharged previously with a discharge diagnosis of complete abortion. 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 in category O03 or O07 instead of code O03.4 or O07.4.
11. Under the heading “Coding of Pathologic Fractures,” language is added to clarify “Active Treatment.” The new language says the seventh character D is reported for encounters after the patient has completed active treatment “for the fracture and is receiving routine care for the fracture during the healing or recovery phase.” Use the other seventh characters, listed under each subcategory in the Tabular List for subsequent treatment encounters for healing problems, such as malunions, nonunions, and sequelae.
12. Guidelines for functional quadriplegia are deleted, effective Oct. 1, 2017.

Section II Key Changes

In Section II, changes occur to admissions/encounters for rehabilitation. When an admission/encounter is for rehabilitation, sequence first the condition for the service performed. The guidelines state, “For example, for an admission/encounter for rehabilitation for right-sided dominant hemiplegia following a cerebrovascular infarction, report code I69.351, Hemiplegia and hemiparesis following cerebral infarction affecting right dominant side, as the first-listed or principal diagnosis.” If the condition that required the rehabilitation service is no longer present:
… report the appropriate aftercare code as the first-listed or principal diagnosis, unless the rehabilitation service is being provided following an injury. For rehabilitation services following active treatment of an injury, assign the injury code with the appropriate seventh character for subsequent encounter as the first-listed or principal diagnosis. For example, if a patient with severe degenerative osteoarthritis of the hip, underwent hip replacement and the current encounter/admission is for rehabilitation, report code Z47.1, Aftercare following joint replacement surgery, as the first-listed or principal diagnosis. If the patient requires rehabilitation post hip replacement for right intertrochanteric femur fracture, report code S72.141D, Displaced intertrochanteric fracture of right femur, subsequent encounter for closed fracture with routine healing, as the first-listed or principal diagnosis.
To ensure proper diagnosis coding, review all sections of the ICD-10 guidelines for 2018, not just Sections I and II.

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John Verhovshek

John Verhovshek, MA, CPC, is a contributing editor at AAPC. He has been covering medical coding and billing, healthcare policy, and the business of medicine since 1999. He is an alumnus of York College of Pennsylvania and Clemson University.

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