In addition to general coding guidelines, there are guidelines for specific diagnoses and/or conditions in the classification. Unless otherwise indicated, these guidelines apply to all health care settings. Please refer to Section II for guidelines on the selection of principal diagnosis.
Code only confirmed cases of HIV infection/illness. This is an exception to the hospital inpatient guideline Section II, H.
In this context, "confirmation" does not require documentation of positive serology or culture for HIV; the provider's diagnostic statstrongent that the patient is HIV positive or has an HIV-related illness is sufficient.
(a) Patient admitted for HIV-related condition
If a patient is admitted for an HIV-related condition, the principal diagnosis should be B20, Human immunodeficiency virus [HIV] disease followed by additional diagnosis codes for all reported HIV-related conditions.
(b) Patient with HIV disease admitted for unrelated condition
If a patient with HIV disease is admitted for an unrelated condition (such as a traumatic injury), the code for the unrelated condition (e.g., the nature of injury code) should be the principal diagnosis. Other diagnoses would be B20 followed by additional diagnosis codes for all reported HIV-related conditions.
An exception to this guideline is if the reason for admission is hemolytic-uremic syndrome associated with HIV disease. Assign code D59.31, Infection-associated hemolytic-uremic syndrome, followed by code B20, Human immunodeficiency virus [HIV] disease.
(c) Whether the patient is newly diagnosed
Whether the patient is newly diagnosed or has had previous admissions/encounters for HIV conditions is irrelevant to the sequencing decision.
(d) Asymptomatic human immunodeficiency virus
Z21, Asymptomatic human immunodeficiency virus [HIV] infection status, is to be applied when the patient without any documentation of symptoms is listed as being "HIV positive," "known HIV," "HIV test positive," or similar terminology. Do not use this code if the term "AIDS" is used or if the patient is treated for any HIV-related illness or is described as having any condition(s) resulting from his/her HIV positive status; use B20 in these cases.
(e) Patients with inconclusive HIV serology
Patients with inconclusive HIV serology, but no definitive diagnosis or manifestations of the illness, may be assigned code R75, Inconclusive laboratory evidence of human immunodeficiency virus [HIV].
(f) Previously diagnosed HIV-related illness
Patients with any known prior diagnosis of an HIV-related illness should be coded to B20. Once a patient has developed an HIV-related illness, the patient should always be assigned code B20 on every subsequent admission/encounter. Patients previously diagnosed with any HIV illness (B20) should never be assigned to R75 or Z21, Asymptomatic human immunodeficiency virus [HIV] infection status.
(g) HIV Infection in Pregnancy, Childbirth and the Puerperium
During pregnancy, childbirth or the puerperium, a patient admitted (or presenting for a health care encounter) because of an HIV-related illness should receive a principal diagnosis code of O98.7-, Human immunodeficiency [HIV] disease complicating pregnancy, childbirth and the puerperium, followed by B20 and the code(s) for the HIV-related illness(es). Codes from Chapter 15 always take sequencing priority.
Patients with asymptomatic HIV infection status admitted (or presenting for a health care encounter) during pregnancy, childbirth, or the puerperium should receive codes of O98.7- and Z21.
(h) Encounters for testing for HIV
If a patient is being seen to determine his/her HIV status, use code Z11.4, Encounter for screening for human immunodeficiency virus [HIV]. Use additional codes for any associated high risk behavior.
If a patient with signs or symptoms is being seen for HIV testing, code the signs and symptoms. An additional counseling code Z71.7, Human immunodeficiency virus [HIV] counseling, may be used if counseling is provided during the encounter for the test.
When a patient returns to be informed of his/her HIV test results and the test result is negative, use code Z71.7, Human immunodeficiency virus [HIV] counseling.
If the results are positive, see previous guidelines and assign codes as appropriate.
(i) HIV managed by antiretroviral medication
If a patient with documented HIV disease, HIV-related illness or AIDS is currently managed on antiretroviral medications, assign code B20, Human immunodeficiency virus [HIV] disease. Code Z79.899, Other long term (current) drug therapy, may be assigned as an additional code to identify the long-term (current) use of antiretroviral medications.
Certain infections are classified in chapters other than Chapter 1 and no organism is identified as part of the infection code. In these instances, it is necessary to use an additional code from Chapter 1 to identify the organism. A code from category B95, Streptococcus, Staphylococcus, and Enterococcus as the cause of diseases classified to other chapters, B96, Other bacterial agents as the cause of diseases classified to other chapters, or B97, Viral agents as the cause of diseases classified to other chapters, is to be used as an additional code to identify the organism. An instructional note will be found at the infection code advising that an additional organism code is required.
Many bacterial infections are resistant to current antibiotics. It is necessary to identify all infections documented as antibiotic resistant. Assign a code from category Z16, Resistance to antimicrobial drugs, following the infection code only if the infection code does not identify drug resistance.
(a) Sepsis
For a diagnosis of sepsis, assign the appropriate code for the underlying syststrongic infection. If the type of infection or causal organism is not further specified, assign code A41.9, Sepsis, unspecified organism.
A code from subcategory R65.2, Severe sepsis, should not be assigned unless severe sepsis or an associated acute organ dysfunction is documented.
(i) Negative or inconclusive blood cultures and sepsis Negative or inconclusive blood cultures do not preclude a diagnosis of sepsis in patients with clinical evidence of the condition; however, the provider should be queried.
(ii) Urosepsis
The term urosepsis is a nonspecific term. It is not to be considered synonymous with sepsis. It has no default code in the Alphabetic Index. Should a provider use this term, he/she must be queried for clarification.
(iii) Sepsis with organ dysfunction
If a patient has sepsis and associated acute organ dysfunction or multiple organ dysfunction (MOD), follow the instructions for coding severe sepsis.
(iv) Acute organ dysfunction that is not clearly associated with the sepsis
If a patient has sepsis and an acute organ dysfunction, but the medical record documentation indicates that the acute organ dysfunction is related to a medical condition other than the sepsis, do not assign a code from subcategory R65.2, Severe sepsis. An acute organ dysfunction must be associated with the sepsis in order to assign the severe sepsis code. If the documentation is not clear as to whether an acute organ dysfunction is related to the sepsis or another medical condition, query the provider.
(b) Severe sepsis
The coding of severe sepsis requires a minimum of 2 codes: first a code for the underlying syststrongic infection, followed by a code from subcategory R65.2, Severe sepsis. If the causal organism is not documented, assign code A41.9, Sepsis, unspecified organism, for the infection. Additional code(s) for the associated acute organ dysfunction are also required.
Due to the complex nature of severe sepsis, some cases may require querying the provider prior to assignment of the codes.
(a) Septic shock generally refers to circulatory failure associated with severe sepsis, and therefore, it represents a type of acute organ dysfunction. For cases of septic shock, the code for the syststrongic infection should be sequenced first, followed by code R65.21, Severe sepsis with septic shock or code T81.12, Postprocedural septic shock. Any additional codes for the other acute organ dysfunctions should also be assigned. As noted in the sequencing instructions in the Tabular List, the code for septic shock cannot be assigned as a principal diagnosis.
If severe sepsis is present on admission, and meets the definition of principal diagnosis, the underlying syststrongic infection should be assigned as principal diagnosis followed by the appropriate code from subcategory R65.2 as required by the sequencing rules in the Tabular List. A code from subcategory R65.2 can never be assigned as a principal diagnosis. When severe sepsis develops during an encounter (it was not present on admission), the underlying syststrongic infection and the appropriate code from subcategory R65.2 should be assigned as secondary diagnoses. Severe sepsis may be present on admission, but the diagnosis may not be confirmed until sometime after admission. If the documentation is not clear whether severe sepsis was present on admission, the provider should be queried.
(a) Documentation of causal relationship
As with all postprocedural complications, code assignment is based on the provider's documentation of the relationship between the infection and the procedure.
(b) Sepsis due to a postprocedural infection
For such cases, the postprocedural infection code, such as T80.2, Infections following infusion, transfusion, and therapeutic injection, T81.4, Infection following a procedure, T88.0, Infection following immunization, or O86.0, Infection of obstetric surgical wound, should be coded first, followed by the code for the specific infection. If the patient has severe sepsis, the appropriate code from subcategory R65.2 should also be assigned with the additional code(s) for any acute organ dysfunction.
(c) Postprocedural infection and postprocedural septic shock
In cases where a postprocedural infection has occurred and has resulted in severe sepsis the code for the precipitating complication such as code T81.4, Infection following a procedure, or O86.0, Infection of obstetrical surgical wound should be coded first followed by code R65.20, Severe sepsis without septic shock. A code for the syststrongic infection should also be assigned.
If a postprocedural infection has resulted in postprocedural septic shock, the code for the precipitating complication such as code T81.4, Infection following a procedure, or O86.0, Infection of obstetrical surgical wound should be coded first followed by code T81.12-, Postprocedural septic shock. A code for the syststrongic infection should also be assigned.
In some cases a noninfectious process (condition), such as trauma, may lead to an infection which can result in sepsis or severe sepsis. If sepsis or severe sepsis is documented as associated with a noninfectious condition, such as a burn or serious injury, and this condition meets the definition for principal diagnosis, the code for the noninfectious condition should be sequenced first, followed by the code for the resulting infection. If severe sepsis is present, a code from subcategory R65.2 should also be assigned with any associated organ dysfunction(s) codes. It is not necessary to assign a code from subcategory R65.1, Systemic inflammatory response syndrome (SIRS) of non-infectious origin, for these cases.
If the infection meets the definition of principal diagnosis, it should be sequenced before the non-infectious condition. When both the associated non-infectious condition and the infection meet the definition of principal diagnosis, either may be assigned as principal diagnosis.
Only one code from category R65, Symptoms and signs specifically associated with systemic inflammation and infection, should be assigned. Therefore, when a non-infectious condition leads to an infection resulting in severe sepsis, assign the appropriate code from subcategory R65.2, Severe sepsis. Do not additionally assign a code from subcategory R65.1, Systemic inflammatory response syndrome (SIRS) of non-infectious origin.
See Section I.C.15. Sepsis and septic shock complicating abortion, pregnancy, childbirth and the puerperium
See Section I.C.16. f. Bacterial sepsis of Newborn
If the reason for admission is hemolytic-uremic syndrome that is associated with sepsis, assign code D59.31, Infection-associated hemolytic-uremic syndrome, as the principal diagnosis. Codes for the underlying systemic infection and any other conditions (such as severe sepsis) should be assigned as secondary diagnoses.
(a) Combination codes for MRSA infection
When a patient is diagnosed with an infection that is due to methicillin resistant Staphylococcus aureus (MRSA), and that infection has a combination code that includes the causal organism (e.g., sepsis, pneumonia) assign the appropriate combination code for the condition (e.g., code A41.02, Sepsis due to Methicillin resistant Staphylococcus aureus or code J15.212, Pneumonia due to Methicillin resistant Staphylococcus aureus). Do not assign code B95.62, Methicillin resistant Staphylococcus aureus infection as the cause of diseases classified elsewhere, as an additional code, because the combination code includes the type of infection and the MRSA organism. Do not assign a code from subcategory Z16.11, Resistance to penicillins, as an additional diagnosis.
(b) Other codes for MRSA infection
When there is documentation of a current infection (e.g., wound infection, stitch abscess, urinary tract infection) due to MRSA, and that infection does not have a combination code that includes the causal organism, assign the appropriate code to identify the condition along with code B95.62, Methicillin resistant Staphylococcus aureus infection as the cause of diseases classified elsewhere for the MRSA infection. Do not assign a code from subcategory Z16.11, Resistance to penicillins.
(c) Methicillin susceptible Staphylococcus aureus (MSSA) and MRSA colonization
The condition or state of being colonized or carrying MSSA or MRSA is called colonization or carriage, while an individual person is described as being colonized or being a carrier. Colonization means that MSSA or MSRA is present on or in the body without necessarily causing illness. A positive MRSA colonization test might be documented by the provider as “MRSA screen positive” or “MRSA nasal swab positive”.
Assign code Z22.322, Carrier or suspected carrier of Methicillin resistant Staphylococcus aureus, for patients documented as having MRSA colonization. Assign code Z22.321, Carrier or suspected carrier of Methicillin susceptible Staphylococcus aureus, for patient documented as having MSSA colonization. Colonization is not necessarily indicative of a disease process or as the cause of a specific condition the patient may have unless documented as such by the provider.
(d) MRSA colonization and infection
If a patient is documented as having both MRSA colonization and infection during a hospital admission, code Z22.322, Carrier or suspected carrier of Methicillin resistant Staphylococcus aureus, and a code for the MRSA infection may both be assigned.
Code only a confirmed diagnosis of Zika virus (A92.5, Zika virus disease) as documented by the provider. This is an exception to the hospital inpatient guideline Section II, H.
In this context, “confirmation” does not require documentation of the type of test performed; the physician's diagnostic statement that the condition is confirmed is sufficient. This code should be assigned regardless of the stated mode of transmission.
If the provider documents "suspected", "possible" or "probable" Zika, do not assign code A92.5. Assign a code(s) explaining the reason for encounter (such as fever, rash, or joint pain) or Z20.828, Contact with and (suspected) exposure to other viral communicable diseases.
(a) Code only confirmed cases
Code only a confirmed diagnosis of the 2019 novel coronavirus disease (COVID-19) as documented by the provider, or documentation of a positive COVID-19 test result. For a confirmed diagnosis, assign code U07.1, COVID-19. This is an exception to the hospital inpatient guideline Section II, H. In this context, "confirmation" does not require documentation of a positive test result for COVID-19; the provider’s documentation that the individual has COVID-19 is sufficient.
If the provider documents "suspected," "possible," "probable," or "inconclusive" COVID-19, do not assign code U07.1. Instead, code the signs and symptoms reported.
(b) Sequencing of codes
When COVID-19 meets the definition of principal diagnosis, code U07.1, COVID-19, should be sequenced first, followed by the appropriate codes for associated manifestations, except when another guideline requires that certain codes be sequenced first, such as obstetrics, sepsis, or transplant complications.
(c) Acute respiratory manifestations of COVID-19
When the reason for the encounter/admission is a respiratory manifestation of COVID-19, assign code U07.1, COVID-19, as the principal/first-listed diagnosis and assign code(s) for the respiratory manifestation(s) as additional diagnoses.
The following conditions are examples of common respiratory manifestations of COVID-19.
For a patient with pneumonia confirmed as due to COVID-19, assign codes U07.1, COVID-19, and J12.89, Pneumonia due to coronavirus disease 2019.
For a patient with acute bronchitis confirmed as due to COVID-19, assign codes U07.1, and J20.8, Acute bronchitis due to other specified organisms.
Bronchitis not otherwise specified (NOS) due to COVID-19 should be coded using code U07.1 and J40, Bronchitis, not specified as acute or chronic.
If the COVID-19 is documented as being associated with a lower respiratory infection, not otherwise specified (NOS), or an acute respiratory infection, NOS, codes U07.1 and J22, Unspecified acute lower respiratory infection, should be assigned.
If the COVID-19 is documented as being associated with a respiratory infection, NOS, codes U07.1 and J98.8, Other specified respiratory disorders, should be assigned.
For acute respiratory distress syndrome (ARDS) due to COVID-19, assign codes U07.1, and J80, Acute respiratory distress syndrome.
For acute respiratory failure due to COVID-19, assign code U07.1, and code J96.0-, Acute respiratory failure.
(d) Non-respiratory manifestations of COVID-19
When the reason for the encounter/admission is a non-respiratory manifestation (e.g., viral enteritis) of COVID-19, assign code U07.1, COVID-19, as the principal/first-listed diagnosis and assign code(s) for the manifestation(s) as additional diagnoses.
(e) Exposure to COVID-19
For asymptomatic individuals with actual or suspected exposure to COVID-19, assign code Z20.822, Contact with and (suspected) exposure to other viral communicable diseases.
For symptomatic individuals with actual or suspected exposure to COVID-19 and the infection has been ruled out, or test results are inconclusive or unknown, assign code Z20.822, Contact with and (suspected) exposure to COVID-19. See guideline I.C.21.c.1, Contact/Exposure, for additional guidance regarding the use of category Z20 codes.
If COVID-19 is confirmed, see guideline I.C.1.g.1.a.
(f) Screening for COVID-19
During the COVID-19 pandemic, a screening code is generally not appropriate. For encounters for COVID-19 testing, including preoperative testing, code as exposure to COVID-19 (guideline I.C.1.g.1.e).
Coding guidance will be updated as new information concerning any changes in the pandemic status becomes available.
(g) Signs and symptoms without definitive diagnosis of COVID-19
For patients presenting with any signs/symptoms associated with COVID-19 (such as fever, etc.) but a definitive diagnosis has not been established, assign the appropriate code(s) for each of the presenting signs and symptoms such as:
If a patient with signs/symptoms associated with COVID-19 also has an actual or suspected contact with or exposure to COVID-19, assign Z20.822, Contact with and (suspected) exposure to COVID-19, as an additional code.
(h) Asymptomatic individuals who test positive for COVID-19
For asymptomatic individuals who test positive for COVID-19, see guideline I.C.1.g.1.a. Although the individual is asymptomatic, the individual has tested positive and is considered to have the COVID-19 infection.
(i) Personal history of COVID-19
For patients with a history of COVID-19, assign code Z86.19, Personal history of COVID-19.
(j) Follow-up visits after COVID-19 infection has resolved
For individuals who previously had COVID-19, without residual symptom(s) or condition(s), and are being seen for follow-up evaluation, and COVID-19 test results are negative, assign codes Z09, Encounter for follow-up examination after completed treatment for conditions other than malignant neoplasm, and Z86.19, Personal history of COVID-19.
For follow-up visits for individuals with symptom(s) or condition(s) related to a previous COVID-19 infection, see guideline I.C.1.g.1.m.
See Section I.C.21.c.8, Factors influencing health states and contact with health services, Follow-up
(k) Encounter for antibody testing
For an encounter for antibody testing that is not being performed to confirm a current COVID-19 infection, nor is a follow-up test after resolution of COVID-19, assign Z01.84, Encounter for antibody response examination.
Follow the applicable guidelines above if the individual is being tested to confirm a current COVID-19 infection.
For follow-up testing after a COVID-19 infection, see guideline I.C.1.g.1.j.
(l) Multisystem Inflammatory Syndrome
For individuals with multisystem inflammatory syndrome (MIS) and COVID-19, assign code U07.1, COVID-19, as the principal/first-listed diagnosis and assign code M35.81, Multisystem inflammatory syndrome, as an additional diagnosis.
If an individual with a history of COVID-19 develops MIS, assign codes M35.81, Multisystem inflammatory syndrome, and U09.91, Post COVID-19 condition, unspecified.
If an individual with a known or suspected exposure to COVID-19, and no current COVID-19 infection or history of COVID-19, develops MIS, assign codes M35.81, Multisystem inflammatory syndrome, and Z20.822, Contact with and (suspected) exposure to COVID-19.
Additional codes should be assigned for any associated complications of MIS.
(m) Post COVID-19 Condition
For sequela of COVID-19, or associated symptoms or conditions that develop following a previous COVID-19 infection, assign a code(s) for the specific symptom(s) or condition(s) related to the previous COVID-19 infection, if known, and code U09.9, Post COVID-19 condition, unspecified.
Code U09.9 should not be assigned for manifestations of an active (current) COVID-19 infection.
If a patient has a condition(s) associated with a previous COVID-19 infection and develops a new active (current) COVID-19 infection, code U09.9 may be assigned in conjunction with code U07.1, COVID-19, to identify that the patient also has a condition(s) associated with a previous COVID-19 infection. Code(s) for the specific condition(s) associated with the previous COVID-19 infection and code(s) for manifestation(s) of the new active (current) COVID-19 infection should also be assigned.
(n) Underimmunization for COVID-19 Status
Code Z28.310, Unvaccinated for COVID-19, may be assigned when the patient has not received a COVID-19 vaccine of any type. Code Z28.311, Partially vaccinated for COVID-19, may be assigned when the patient has been partially vaccinated for COVID-19 as per the recommendations of the Centers for Disease Control and Prevention (CDC) in place at the time of the encounter. For information, visit the CDC's website https://www.cdc.gov/coronavirus/2019-ncov/vaccines/.