The 2nd character defines the particular body system or general physiological system or anatomical region involved.
Administration section codes represent procedures for putting in or on a therapeutic, prophylactic, protective, diagnostic, nutritional or physiological substance. Administration procedure codes have a first character value of “3”. The body system character contains three values: circulatory system, indwelling device, and physiological systems and anatomical regions. The circulatory body system is used for transfusion procedures. There are three root operations in the administration section:
The fourth character specifies the body system/region. It identifies the site where the substance is administered, not the site where the substance administered takes effect. Sites include skin and mucous membrane, subcutaneous tissue and muscle. These differentiate intradermal, subcutaneous, and intramuscular injections respectively. Other sites include eye, respiratory tract, peritoneal cavity, and epidural space.
The fifth character specifies approaches as defined in the medical and surgical section. The approach for intradermal, subcutaneous and intramuscular introductions (i.e., injections) is percutaneous. If a catheter is placed to introduce a substance into an internal site within the circulatory system, then the approach is percutaneous. For example, if a catheter is advanced directly into the heart to introduce contrast for angiography, then the procedure would be coded as a percutaneous introduction of contrast into the heart.
The body systems/regions for arteries and veins are peripheral artery, central artery, peripheral vein and central vein. The peripheral artery or vein is typically used when a substance is introduced locally into an artery or vein. For example, chemotherapy is the introduction of an antineoplastic substance into a peripheral artery or vein by a percutaneous approach. In general, the substance introduced into a peripheral artery or vein has a systemic effect.
The central artery or vein is typically used when the site where the substance is introduced is distant from the point of entry into the artery or vein. For example, the introduction of a substance directly at the site of a clot within an artery or vein using a catheter is coded as an introduction of a thrombolytic substance into a central artery or vein by a percutaneous approach. In general, the substance introduced into a central artery or vein has a local effect.
The sixth character specifies the substance being introduced. Broad categories of substances are defined, such as anesthetic, contrast, dialysate, and blood products such as platelets. The seventh character is a qualifier, and is used to indicate whether a substance transfused is autologous or nonautologous, or to further specify a substance introduced.