Coding Drugs, Medicaments and Biological Substances in ICD-9 CM and ICD-10 CM Blog

1. ICD-9 CM & ICD-10 CM CODING OF DRUGS, MEDICAMENTS AND BIOLOGICAL SUBSTANCES
One of the major changes seen in the structure and organization of ICD-10 CM is in the
classification of Poisonings and Adverse Effect of Drugs, Medicaments and Biological
Substances, categories T36-T50. These categories are located in Chapter 19: Injury, Poisoning,
and Certain Other Consequences of External Causes (S00-T88) in ICD-10 CM. They are found
in Chapter 17: Injury and Poisoning (800-999) in the categories 960-979 for a current condition
in ICD-9 CM. In ICD-10 CM, some of the categories in Chapter 19 call for a 7th
character to
complete the code. Categories T36-T50 must meet this requirement. The 7th
characters should
be one of three below:
A=Initial Encounter. This encounter is the first time the patient is seen for the condition. It does
not matter when the treatment is administered as long as it is the first time treatment is being
administered.
B=Subsequent Encounter. This encounter is for any treatment received after the initial encounter
for treatment. The treatment is given during what is considered the recuperation period and is
often termed as a “follow-up visit.”
C=Sequela. This encounter is for the treatment of conditions that are a result of a condition.
The code for the injury with the 7th
character “S” and the code for the sequela are both coded.
The coder is to pay particular attention to the sequencing in this case. The sequela is sequenced
first.
ICD-9 CM codes do not have a 7th
character “S” requirement. They do, however, have a
late effect code, 909.0 Late Effect of Poisoning due to Drug, Medicinal, or Biological Substance
or 909.5 Late Effect of Adverse Effect of Drug, Medical or Biological Substance. For
subsequent (follow-up) visits an appropriate “V” code is used followed by the appropriate
poisoning code for further specificity. Another difference between the two nomenclatures is that
ICD-10 CM codes do not have supplemental codes to describe the circumstances surrounding the
nature of the poisoning. Each drug category has a code for accidental, intentional, assault,
undetermined, and adverse effect (which is therapeutic use in ICD-9 CM). In both ICD-9 CM
and ICD-10 CM, codes would be used expressing the result of the adverse effect; unless the
result of the adverse effect is unknown. Then the coder would use codes 995.20 or 995.29 in
ICD-9 CM in conjunction with the applicable codes from the Supplementary Classification of
External Causes of Injury and Poisoning (E000-E999) category. Codes T50.905 (7th
character A,
D, or S) or T50.906 (7th
character A, D, or S) would be applied in ICD-10 CM. Lastly, the ICD-
10 CM code set has codes for “Underdosing” which is not the case in ICD-9 CM. Let’s look at
comparison coding for poisoning of the drug Digoxin in a patient who is being treated for the
first time.

2. DIGOXIN POISONING
As stated previously, the adverse effect of Digoxin would require that the coder know the nature
of the adverse effect (i.e., tachycardia, vomiting) and this would be coded in both ICD-9CM and
ICD-10 CM. In ICD-9 CM, the code would be followed by the code E942.1. In ICD-10 CM,
the code would be followed by T46.05XA.
Finally, Underdosing is referred to as taking less of a prescribed drug. ICD-9 CM does not have
a specific code for Underdosing. The coder must code the manifestation of the Underdosing,
such as an exacerbation of the condition for which the drug is being taken. In ICD-10, the
exacerbated condition and T46.06XA should be coded.
NOTE: In ICD-10 CM, the Underdosing code should not be used as the principal
diagnosis. It is considered a secondary code. The condition that results from the
Underdosing should be the principle diagnosis.
NOTE: Codes stating the intent, if known of the Underdosing should also be coded.
Accidental
•ICD-9 (972.1 & E858.3)
•ICD-10 (T46.01XA)
Intentional
•ICD-9 (972.1 & E950.4)
•ICD-10 (T46.02XA)
Assault
•ICD-9 (972.1 & E962.0)
•ICD-10 (T46.03XA)
Undetermined
•ICD-9 (972.1 & E980.4)
•ICD-10 (T46.04XA)

3. Cynthia Brown, MBA, RHIT, CCS
AHIMA Approved ICD-10 CM/PCS Trainer
CyntCoding Health Information Services
Phone: 404-992-8984/E-Fax: 678-805-4919
P.O. Box 3019
Decatur, GA 30031
cyntcoder@cyntcodinghealthinformationservices.com
www.cyntcodinghealthinformationservices.com
http://cyntcodinghealthinformationservices.blogspot.com
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