Chapter 1 in the I-10 Tabular is Certain Infectious and Parasitic Diseases (A00-B99), which classifies diseases according to the etiology (cause) of the disease. Because infectious and parasitic conditions can affect various parts of the body, the chapter contains a wide variety of codes and complex terminology.

In this chapter there are many instances of combination coding and multiple coding. Remember: Combination coding is when one code fully describes the conditions and/or manifestations. Multiple coding is when it takes more than one code to fully describe the condition, circumstance, or manifestation, and then sequencing of multiple codes is considered.

Examples

Combination coding

Diagnosis:	Candidiasis infection of the mouth
Index:	Candidiasis, candidal, mouth B37.0
Tabular:	B37.0 Candidal stomatitis
Code:	B37.0 Candidiasis infection of the mouth
B37.0 fully describes the diagnosis.

Multiple coding

Diagnosis:	Urinary tract infection due to Escherichia coli (E. coli)
Index:	Infection, infected, infective; urinary (tract) NEC N39.0
Tabular:	N39.0 Urinary tract infection, site not specified Use additional code (B95-B97), to identify infectious agent.

Code N39.0 does not fully describe the condition. The instructions in the Tabular for code N39.0 state that you are to also code the organism causing the urinary tract infection. To locate a causative organism, you locate the main term “Infection” in the Index and then the subterm of “bacterial” followed by the subterm “as cause of disease classified elsewhere,” and then the specific organism, which in the example is Escherichia coli.

Index:	Infection, bacterial, as cause of disease classified elsewhere, Escherichia coli B96.2
Tabular:	B96 Other bacterial agents as the cause of diseases classified elsewhere B96.2 Escherichia coli [E. coli] as the cause of diseases classified elsewhere

The urinary tract infection is sequenced first, followed by the bacterial organism.

Codes:

N39.0, B96.2 Urinary tract infection due to Escherichia coli (E. coli)

Multiple coding is necessary to fully describe the infection of the urinary tract and the causative organism, E. coli.

Resistant infections

ICD-10 OFFICIAL GUIDELINES FOR CODING AND REPORTING

SECTION I.C. Chapter-specific coding guidelines 1.c. infections resistant to antibiotics

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 codes (a00-a99)

The A codes include the blocks illustrated in Figure 4–1.

FIGURE 4–1 Blocks in the A codes of the I-10. (From Buck CJ: *2012 ICD-10-CM Standard Edition DRAFT (Softbound)*, St. Louis, 2012, Saunders.)

Antibiotics are used to kill the bacteria that cause disease, but many antibiotics that were historically effective against bacteria are no longer effective. Most bacteria have become resistant to some antibiotics, but other bacteria are resistant to many antibiotics (multiresistant organisms, MROs, or superbugs). Those antibiotics that have been widely prescribed are no longer effective—for example, methicillin-resistant Staphylococcus aureus (MRSA), multi-drug-resistant Mycobacterium tuberculosis (MDR-TB), and vancomycin-resistant Enterococcus (VRE). Penicillin-resistant Streptococcus pneumonia has also increased worldwide. When reporting an infection that is antibiotic resistant, report the infection first followed by Z16 (Infection with drug-resistant microorganism). This is the mechanism by which drug-resistant microorganisms are tracked. Staphylococcus aureus is the exception to the Z16 rule. For Staphylococcus aureus, specific codes designate the status of resistance to methicillin:

B95.61 Methicillin susceptible Staphylococcus aureus infection as the cause of diseases classified elsewhere (MSSA)

B95.62 Methicillin resistant Staphylococcus aureus infection as the cause of diseases classified elsewhere (MRSA)

MSSA and MRSA infections are reported elsewhere in ICD-10 as well for some system-specific infections like pneumonia.

QUICK CHECK 4-1

1. What code would you reference when reporting MRSA? ___________________

2. What is the drug resistance in VRE? ___________________

3. What does the S stand for in MRSA? ___________________

Sepsis, severe sepsis, and septic shock

SIRS is an inflammatory condition, also known as systemic inflammatory response syndrome. The inflammation is a response to microorganisms in the tissue, blood, lungs, skin, or urinary system. SIRS is diagnosed when two or more of the following are present:

hypothermia or fever (<97°F or >100°F or < 38°C or > 36°C)

tachycardia (>90-100 bpm)

increased respiratory rate (>20 breaths per minute or PaCO₂ < 32 mm Hg)

increased or decreased white blood count (<4,000 or >12,000)

SIRS is classified as severe sepsis when there is organ dysfunction, hypotension, or collection of fluids in the tissues (hypoperfusion). To report severe sepsis, you would report an R65.2x code but remember that severe sepsis can only be reported if severe sepsis is documented in the patient health record. The provider will make the diagnosis of SIRS. If the documentation indicates that the patient has SIRS and organ dysfunction and that the organ dysfunction is related to a condition other than SIRS, severe sepsis is not reported. There must be a documented correlation between the SIRS and the organ dysfunction to report severe sepsis. It will require at least three codes to report severe sepsis: a code for the underlying systemic infection, an R65.2x code, and a code or codes to report organ dysfunction. When the microorganism is not documented, report A41.9, Sepsis, unspecified.

Septic shock is a circulatory failure that represents a type of organ dysfunction. Report the underlying infection first, followed by R65.21, Severe sepsis with septic shock, and codes for any organ dysfunction documented in the health record. Code R65.21 is never assigned as the first-listed diagnosis because it is a result of an underlying infection; therefore, the infection is the first-listed diagnosis followed by the severe sepsis.

ICD-10 OFFICIAL GUIDELINES FOR CODING AND REPORTING

SECTION I.C. 1.d. Sepsis, severe sepsis, and septic shock

2) Septic shock

Septic shock generally refers to circulatory failure associated with severe sepsis, and therefore, it represents a type of acute organ dysfunction. For all cases of septic shock, the code for the underlying systemic 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.

Septic shock indicates the presence of severe sepsis. Code R65.21, Severe sepsis with septic shock, must be assigned if septic shock is documented in the medical record, even if the term severe sepsis is not documented.

3) Sequencing of severe sepsis

If severe sepsis is present on admission, and meets the definition of principal diagnosis, the underlying systemic 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 systemic 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.

SIRS may develop as a result of a procedure and becomes a complication of the medical care the patient received. In these instances, report a postprocedural infection first, followed by a code for the specific infection.

Examples

Subcategory T80.2 Infections following infusion, transfusion, or therapeutic injection, report an additional code to identify the specific infection; such as sepsis [A41.9]

Subcategory T81.4 Infection following a procedure; report an additional code to identify infection

Subcategory O86.0 Infection of obstetric surgical wound, report an additional code (B95-B97) to identify infectious agent

ICD-10 OFFICIAL GUIDELINES FOR CODING AND REPORTING

SECTION I.C. 1.d. Sepsis, severe sepsis, and septic shock

1) Coding of Sepsis and Severe Sepsis

(a) Sepsis

For a diagnosis of sepsis, assign the appropriate code for the underlying systemic 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 systemic 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.

4) Sepsis and severe sepsis with a localized infection

If the reason for admission is both sepsis or severe sepsis and a localized infection, such as pneumonia or cellulitis, a code(s) for the underlying systemic infection should be assigned first and the code for the localized infection should be assigned as a secondary diagnosis. If the patient has severe sepsis, a code from subcategory R65.2 should also be assigned as a secondary diagnosis. If the patient is admitted with a localized infection, such as pneumonia, and sepsis/severe sepsis doesn’t develop until after admission, the localized infection should be assigned first, followed by the appropriate sepsis/severe sepsis codes.

5) Sepsis due to a postprocedural infection

(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.

In cases where a postprocedural infection has occurred and has resulted in severe sepsis and 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 R65.21, Severe sepsis with septic shock and a code for the systemic infection.

6) Sepsis and severe sepsis associated with a noninfectious process (condition)

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.18. SIRS due to non-infectious process

TOOLBOX

Robert has sepsis resulting from a postprocedural infection that is now complicating his care.

Questions

1. Sepsis resulting from a postprocedural infection is considered a ________________.

2. If the documentation stated that Robert’s sepsis was severe, you would reference what subcategory for code assignment? ______________________________

3. When reporting severe sepsis, you would also report what dysfunction? ______________________________

Answers

1. complication, 2. R65.2, 3. organ dysfunction

Z72.51	High risk heterosexual behavior
Z72.52	High risk homosexual behavior
Z72.53	High risk bisexual behavior

If the patient has signs or symptoms when presenting for HIV screening, report the signs and symptoms and if counseling is provided during the encounter, report Z71.7, HIV counseling. When the patient returns for the results of the HIV screening and the results are negative, report Z71.7.

ICD-10 OFFICIAL GUIDELINES FOR CODING AND REPORTING

SECTION I.C.1. Chapter 1: certain infectious and parasitic diseases (a00-b99)

a. Human Immunodeficiency Virus (HIV) Infections

1) Code only confirmed cases

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 statement that the patient is HIV positive, or has an HIV-related illness is sufficient.

2) Selection and sequencing of HIV codes

(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.

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.

(Note from author: State laws may have rules for coding and submitting AIDS diagnosis. Example: Under New York State Law, confidential HIV-related information can only be given to people the patient allows to have it by signing a written release or to people who need to know the HIV status in order to provide medical care and services.)

(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.

EXERCISE 4-2 B Code Viral Infections

Complete the following in Chapter 4 of your “ICD-10-CM Online Training Modules:”

Online Lesson 1, Screens 12-19

Neoplasms

Chapter 2 of the I-10 contains codes C00-D49 to report neoplasms. There are extensive Guidelines that must be understood and followed to correctly code neoplasms.

ICD-10 OFFICIAL GUIDELINES FOR CODING AND REPORTING

SECTION I.C.2. Chapter 2: neoplasms (C00-D49)

General guidelines

Chapter 2 of the ICD-10-CM contains the codes for most benign and all malignant neoplasms. Certain benign neoplasms, such as prostatic adenomas, may be found in the specific body system chapters. To properly code a neoplasm it is necessary to determine from the record if the neoplasm is benign, in-situ, malignant, or of uncertain histologic behavior. If malignant, any secondary (metastatic) sites should also be determined.

Primary malignant neoplasms overlapping site boundaries

A primary malignant neoplasm that overlaps two or more contiguous (next to each other) sites should be classified to the subcategory/code .8 (‘overlapping lesion’), unless the combination is specifically indexed elsewhere. For multiple neoplasms of the same site that are not contiguous such as tumors in different quadrants of the same breast, codes for each site should be assigned.

Malignant neoplasm of ectopic tissue

Malignant neoplasms of ectopic tissue are to be coded to the site mentioned, e.g., ectopic pancreatic malignant neoplasms are coded to pancreas, unspecified (C25.9).

The neoplasm table in the Alphabetic Index should be referenced first. However, if the histological term is documented, that term should be referenced first, rather than going immediately to the Neoplasm Table, in order to determine which column in the Neoplasm Table is appropriate. For example, if the documentation indicates “adenoma,” refer to the term in the Alphabetic Index to review the entries under this term and the instructional note to “see also neoplasm, by site, benign.” The table provides the proper code based on the type of neoplasm and the site. It is important to select the proper column in the table that corresponds to the type of neoplasm. The Tabular List should then be referenced to verify that the correct code has been selected from the table and that a more specific site code does not exist.

See Section I.C.21. Factors influencing health status and contact with health services, Status, for information regarding Z15.0, codes for genetic susceptibility to cancer.