Final answer:
The abbreviation that appears in both the alphabetic index and tabular list in medical coding is NOS, which stands for 'Not Otherwise Specified.'
Step-by-step explanation:
The abbreviation that appears in the alphabetic index as well as the tabular list is NOS. NOS stands for 'Not Otherwise Specified.' It is used in medical coding when there is insufficient information to assign a more specific code.
For example, if a patient presents with a symptom that cannot be classified under a specific diagnosis, the NOS abbreviation may be used to indicate this lack of specificity. It allows healthcare professionals to document and code for the patient's condition appropriately, even without a definitive diagnosis.