Use of ICD-9-CM to the Greatest Degree of Accuracy and Completeness
The testing facility or the interpreting physician should code the ICD-9-CM code that provides the highest degree of accuracy and completeness for the diagnosis resulting from test, or for the sign(s)/symptom(s) that prompted the ordering of the test.
In the past, there has been some confusion about the meaning of “highest degree of specificity” and “reporting the correct number of digits.” In the context of ICD-9-CM coding, the “highest degree of specificity” refers to assigning the most precise ICD-9-CM code that most fully explains the narrative description in the medical chart of the symptom or diagnosis.
Example 1: A chest X-ray reveals a primary lung cancer in the left lower lobe. The interpreting physician should report the ICD-9-CM code as 162.5 for malignancy of the left “lower lobe, bronchus or lung,” not the code for a malignancy of “other parts of bronchus or lung” (162.8) or the code for “bronchus and lung unspecified” (162.9).
Example 2: If a sputum specimen is sent to a pathologist and the pathologist confirms growth of “streptococcus, type B,” which is indicated in the patient’s medical record, the pathologist should report a primary diagnosis as 482.32 (Pneumonia due to streptococcus, Group B). However, if the pathologist is unable to specify the organism, then the pathologist should report the primary diagnosis as 486 (Pneumonia, organism unspecified).
To report the correct number of digits when using ICD-9-CM, refer to the following instructions:
ICD-9-CM diagnosis codes are composed of codes with three, four or five digits. Codes with three digits are included in ICD-9-CM as the heading of a category of codes that may be further subdivided by the use of fourth and/or fifth digits to provide greater specificity. Assign three-digit codes only if there are no four-digit codes within that code category. Assign four-digit codes only if there is no fifth-digit subclassification for that category. Assign the fifth-digit subclassification code for those categories where it exists.
Example 3: A patient is referred to a physician with a diagnosis of diabetes mellitus. However, there is no indication that the patient has diabetic complications or that the diabetes is out of control. It would be incorrect to assign code 250 since all codes in this series have five digits. Reporting only three digits of a code that has five digits would be incorrect. One must add two more digits to make it complete. Because the type (adult onset/juvenile) of diabetes is not specified, and there is no indication that the patient has a complication or that the diabetes is out of control, the correct ICD-9-CM code would be 250.00. The fourth and fifth digits of the code would vary depending on the specific condition of the patient.