Question: I have a pediatrician that is using A64 when he tests a patient for a sexually transmitted disease (STD). However, the patient has no symptoms. Should we use this code under these circumstances? Michigan Subscriber Answer: You would only use A64 (Unspecified sexually transmitted disease) first, if your provider must document that the patient actually has an STD, and second, if there was no other documentation or specific code for the particular STD your provider has diagnosed. If the patient is asymptomatic, however, you should regard the test as a screening and assign it the appropriate Z code. You would use Z11.3 (Encounter for screening for infections with a predominantly sexual mode of transmission) if the provider was screening for an STD other than human immunodeficiency virus (HIV) or human papillomavirus (HPV). They have their own separate encounter codes: Z11.4 (Encounter for screening for human immunodeficiency virus [HIV]) and Z11.51 (Encounter for screening for human papillomavirus (HPV)). And don’t forget these additional encounter codes: Depending on your pediatrician’s documentation, other encounter codes may come into play in this scenario, including contact codes Z20.6 (Contact with and (suspected) exposure to human immunodeficiency virus [HIV]), Z20.828 (Contact with and (suspected) exposure to other viral communicable diseases), and Z20.89 (Contact with and (suspected) exposure to other communicable diseases). Also, under the right circumstances, you could also find yourself using Z72.5- (High risk sexual behavior) and Z71.89 (Other specified counseling) in such situations.