Oncology & Hematology Coding Alert

Question: How do I report adverse effects of chemotherapy? If a patient experiences throat pain from vomiting following chemotherapy, how do I choose between T45.1X1- and T45.1XS-?

California Subscriber

Answer: The difference between coding T45.1X1- (Poisoning by antineoplastic and immunosuppressive drugs, accidental (unintentional)) and T45.1X5- (Adverse effect of antineoplastic and immunosuppressive drugs) depends on whether your provider administered the chemotherapy correctly or incorrectly.

If you consult table I.C.19.e “Adverse effects, poisoning, underdosing and toxic effects” in the ICD-10-CM guidelines, you’ll see that you will use an adverse effect code from T36-T50 (Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances). ICD-10-CM guidelines also instruct you to code first the nature of the adverse effect.

However, if the provider administers the drug improperly (for example, if your provider has incorrectly calculated the drug dosage), then ICD-10-CM instructs you to use a poisoning code first followed by any and all manifestations of the poisoning. You would also add the manifestation codes and external cause code Y63.- (Failure in dosage during surgical and medical care) as instructed by ICD-10CM coding guidelines.

So, if your provider administered the chemotherapy correctly, you’ll code

• R11.10 (Vomiting, unspecified)
• R07.0 (Pain in throat)
• T45.1X5-

But if there was a problem with the way your provider administered the chemo, you would code

• T45.1X1-
• R11.10
• R07.0
• A code from Y63.6-Y63.9 as applicable

And remember: You will need to add the appropriate 7th character (A for the initial encounter, D for a subsequent encounter, or S for sequela of the condition once it has resolved) to either of the T45.- codes.