Oncology & Hematology Coding Alert

Question: A patient experiences throat pain from vomiting following chemotherapy. In addition to coding for these conditions, which of the following should I use: T45.1X1- or T45.1X5?

Colorado Subscriber

Answer: Code choice in this situation depends on whether or not your provider made an error in the prescription or the administration of the drug. You would use T45.1X5- (Adverse effect of antineoplastic and immunosuppressive drugs) for an adverse effect to a correctly prescribed and properly administered chemotherapy drug, and T45.1X1- (Poisoning by antineoplastic and immunosuppressive drugs, accidental (unintentional)) for “poisoning or reaction to the improper use of a medication (e.g., overdose, wrong substance given or taken in error, wrong route of administration)” per ICD-10-CM.

Code sequencing for an adverse effect to correctly prescribed and properly administered chemotherapy would then follow ICD-10-CM guideline I.C.19.e.5.a. This tells you to “assign the appropriate code for the nature of the adverse effect followed by the appropriate code for the adverse effect of the drug.”

However, if the provider administers the drug improperly, then ICD-10-CM guideline I.C.19.e.5.b instructs you to use a poisoning code from T36-T50 (Poisoning by, adverse effects of and underdosing of drugs, medicaments and biological substances) first, followed by any and all manifestations of the poisoning. In addition to the manifestation codes, you would also add an external cause code from Y63.- (Failure in dosage during surgical and medical care) as further instructed by ICD-10-CM coding guidelines. Don’t miss adding the 4th digit depending on the type of dosing error, and following the excludes notes for dosing error not accidental described within T36-T50.

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.