Otolaryngology Coding Alert

Question: What’s the diagnosis coding for a patient experiencing an allergic reaction (vomiting, rashes) to azithromycin following treatment for an ear infection? The patient stated that they did not finish the 5-day cycle following the reactions.

Indiana Subscriber

Answer: The coding for complications following prescribed medication depends on a few variables. These include the type of medication prescribed and the means/intent of the patient when taking the medication. For instance, when a patient experiences a reaction to an antibiotic prescription, you’ll report a code from category code T36 (Poisoning by, adverse effect of and underdosing of systemic antibiotics). From there, you’ll have to consider the type of antibiotic and the means in which the patient was poisoned (accidental, adverse effect, intentional self-harm, undetermined, etc.).

Before considering codes and sequencing of codes, you want to have the proper guidelines available to you from the ICD-10-CM code book. Consider the following instructions on coding adverse effect diagnoses from Section I.C.19.e.5.a:

• When coding an adverse effect of a drug that has been correctly prescribed and properly administered, assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug (T36-T50). The code for the drug should have a 5th or 6th character “5” (for example T36.0X5-)

These guidelines instruct you to code the symptoms followed by the poisoning code from category code T36. For vomiting, you’ll report code R11.10 (Vomiting, unspecified), but the coding for the rash requires a little more attention to detail or else you might find yourself incorrectly reporting code R21 (Rash and other nonspecific skin eruption). In the ICD-10-CM Alphabetic Index, you’ll find Rash ? drug (internal use), which leads you to code L27.0 (Generalized skin eruption due to drugs and medicaments taken internally).

Finally, you’ll home in on the correct fourth character under category code T36. Adverse reactions to penicillin may be reported as T36.0 (Poisoning by, adverse effect of and underdosing of penicillins), but you’ll find no such luck with azithromycin. Instead, you should report code T36.8X5A (Adverse effect of other systemic antibiotics, initial encounter). In this example, you do have documentation that the patient did not finish their cycle, which technically qualifies as underdosing. However, in order to report code T36.8X6A (Underdosing of other systemic antibiotics, initial encounter), the patient must have experienced the adverse reaction due to the fact that they took less of, or discontinued, their prescription treatment.