Radiology Coding Alert

Question: I’m working on a computed tomography (CT) maxillofacial for a patient with a chronic left ear infection. The indication also states that the patient has experienced an allergic reaction (vomiting, rashes) to azithromycin following treatment. What’s the ICD-10-CM coding?

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Answer: The chronic ear infection is the underlying reason for the visit. For that diagnosis, you’ll use the ICD-10-CM Alphabetic Index to search for Infection ? ear (middle) since you don’t know whether the infection is located in the middle or inner ear. From there, you’ll be directed to Otitis media. Report otherwise unspecified chronic otitis media with code H66.92 (Otitis media, unspecified, left ear).

Since the allergic reaction is related to treatment for the underlying visit, you will want to include the complication to a prescribed medication (and adverse reactions) as secondary codes. 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).