Coding Uncertain Diagnoses
Accurate diagnosis coding is crucial for patient care and compliant, optimal reimbursement. In the outpatient setting, you should never assign a diagnosis unless that diagnosis has been confirmed by diagnostic testing, or is otherwise certain. Uncertain diagnoses include those that are:
- “Rule out”
If you are unable to determine a definitive diagnosis, you should document and code for the signs, symptoms, abnormal test result(s), or other conditions that prompted the patient encounter. ICD-10-CM coding guidelines confirm, “Each healthcare encounter should be coded to the level of certainty known for that encounter. If a definitive diagnosis has not been established by the end of the encounter, it is appropriate to report codes for sign(s) and/or symptom(s) in lieu of a definitive diagnosis.”
Many signs and symptoms codes are found in ICD-10-CM Chapter 18 (R00.0–R99); however, signs and symptoms codes may appear throughout the ICD-10-CM codebook. Chapter 18 defines signs and symptoms as:
(a) cases for which no more specific diagnosis can be made even after all the facts bearing on the case have been investigated;
(b) signs or symptoms existing at the time of initial encounter that proved to be transient and whose causes could not be determined;
(c) provisional diagnosis in a patient who failed to return for further investigation or care;
(d) cases referred elsewhere for investigation or treatment before the diagnosis was made;
(e) cases in which a more precise diagnosis was not available for any other reason;
(f) certain symptoms, for which supplementary information is provided, that represent important problems in medical care in their own right.
For example, you document “Fatigue, suspect iron deficiency anemia,” you should code only for the fatigue because the encounter note does not confirm the diagnosis of iron deficiency anemia.
“Abnormal test result” (e.g., Abnormal findings on examination of blood, without diagnosis, R70-R79) is acceptable as a primary diagnosis when ordering follow-up testing based on positive findings. If diagnostic testing confirms a diagnosis, report the definitive diagnosis rather than the signs and symptoms that prompted the test.
If the definitive diagnosis fails to present a complete picture of the patient’s condition, you may assign additional signs and symptoms codes. You also may report unrelated signs and symptoms that affect your medical decision-making, or otherwise influence the patient’s care. However, per ICD-10-CM Official Guidelines, “Signs and symptoms that are associated routinely with a disease process should not be assigned as additional codes, unless otherwise instructed by the classification.”
Note that the above coding rules apply to professional services, and to those services performed in an outpatient setting. In the inpatient setting for facility diagnosis coding, you may report suspected or rule out diagnoses as if the condition exists. If a diagnosis is uncertain at the time of discharge, the condition should be coded as if it existed or was established.
HIV Is an Exception
HIV is an exception to the above rule: HIV is the only condition that must be confirmed if it is to be reported in the in-patient setting. Confirmation does not require documentation of positive serology or culture for HIV. The physician’s diagnostic statement that the patient is HIV positive or has an HIV-related illness is sufficient.