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Official Description

Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], fluorescence immunoassay [FIA], immunochemiluminometric assay [IMCA]) qualitative or semiquantitative; Streptococcus, group A

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 87430 refers to a laboratory test designed to detect the presence of the antigen associated with Streptococcus, group A, also known as S. pyogenes. This test employs various immunoassay techniques, which are analytical methods that utilize the immune response to identify specific antigens in a sample. The techniques mentioned include enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). Group A Streptococcus is a significant pathogen responsible for a range of illnesses, including strep throat, rheumatic fever, scarlet fever, and streptococcal sepsis. The latter can occur when the bacteria spread from the nasopharynx into the bloodstream, leading to severe systemic infections, particularly in hospital settings. In the testing process, a sample is collected and either placed in a fixative or sent fresh to the laboratory for analysis. The EIA and ELISA methods are particularly sensitive, capable of detecting minute quantities of the antigen by utilizing a secondary enzyme-labeled antibody that binds to the antigen. This binding triggers a chromogenic reaction, resulting in a visible color change or fluorescence that indicates the presence of the antigen. Qualitative results provide a simple positive or negative outcome, while semi-quantitative results offer a measure of the antigen concentration based on colorimetric readings. The FIA method employs a fluorescent compound to detect the binding of a specific antibody to the antigen, while IMCA utilizes antibodies labeled with a chemiluminescent substance to quantify the antigen-antibody complex through light emission. Overall, this test is crucial for the timely diagnosis and management of infections caused by Group A Streptococcus.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The CPT® Code 87430 is indicated for the detection of Streptococcus, group A, in patients presenting with symptoms or conditions associated with infections caused by this bacterium. The following are specific indications for performing this test:

  • Strep Throat A common infection characterized by a sore throat, fever, and swollen lymph nodes, often requiring prompt diagnosis and treatment.
  • Rheumatic Fever A serious inflammatory condition that can develop after a strep throat infection, affecting the heart, joints, skin, and brain.
  • Scarlet Fever A disease that can occur in conjunction with strep throat, marked by a distinctive red rash and fever.
  • Streptococcal Sepsis A severe and potentially life-threatening condition resulting from the spread of Group A Streptococcus into the bloodstream.

2. Procedure

The procedure for conducting the test associated with CPT® Code 87430 involves several key steps to ensure accurate detection of the Streptococcus, group A antigen:

  • Sample Collection A sample is obtained from the patient, typically through a throat swab or other appropriate method. This sample is crucial for the subsequent analysis and must be handled properly to maintain its integrity.
  • Sample Preparation The collected sample is either placed in a fixative to preserve it for laboratory analysis or sent fresh to the laboratory. Proper preparation is essential to prevent degradation of the antigen.
  • Immunoassay Technique Application The laboratory technician applies one of the immunoassay techniques—EIA, ELISA, FIA, or IMCA—to the prepared sample. Each technique utilizes specific reagents and conditions to facilitate the detection of the antigen.
  • Detection and Measurement The presence of the Streptococcus, group A antigen is detected through a reaction that produces a visible signal, such as a color change or fluorescence. The results can be qualitative (positive or negative) or semi-quantitative, providing information on the concentration of the antigen.
  • Result Interpretation The laboratory personnel interpret the results based on the reactions observed during the immunoassay process. This interpretation is critical for determining the presence of an active infection and guiding further clinical management.

3. Post-Procedure

After the completion of the test associated with CPT® Code 87430, the following post-procedure considerations are important:

Results are typically available within a short timeframe, allowing for timely clinical decision-making. If the test is positive, healthcare providers may initiate appropriate treatment for the identified infection, which could include antibiotics. In cases of negative results, further evaluation may be necessary if clinical symptoms persist. It is also essential for healthcare providers to communicate the results to the patient and discuss any necessary follow-up actions or additional testing that may be warranted based on the clinical context.

Short Descr STREP A AG IA
Medium Descr IAAD IA STREPTOCOCCUS GROUP A
Long Descr Infectious agent antigen detection by immunoassay technique (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], fluorescence immunoassay [FIA], immunochemiluminometric assay [IMCA]), qualitative or semiquantitative; Streptococcus, group A
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) Yes
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 206 - Microscopic examination (bacterial smear, culture, toxicology)
QW Clia waived test
59 Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25.
CR Catastrophe/disaster related
26 Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number.
76 Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
91 Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient.
95 Synchronous telemedicine service rendered via a real-time interactive audio and video telecommunications system: synchronous telemedicine service is defined as a real-time interaction between a physician or other qualified health care professional and a patient who is located at a distant site from the physician or other qualified health care professional. the totality of the communication of information exchanged between the physician or other qualified health care professional and the patient during the course of the synchronous telemedicine service must be of an amount and nature that would be sufficient to meet the key components and/or requirements of the same service when rendered via a face-to-face interaction. modifier 95 may only be appended to the services listed in appendix p. appendix p is the list of cpt codes for services that are typically performed face-to-face, but may be rendered via a real-time (synchronous) interactive audio and video telecommunications system.
CC Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed)
GA Waiver of liability statement issued as required by payer policy, individual case
GC This service has been performed in part by a resident under the direction of a teaching physician
GV Attending physician not employed or paid under arrangement by the patient's hospice provider
GW Service not related to the hospice patient's terminal condition
Q6 Service furnished under a fee-for-time compensation arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area
SA Nurse practitioner rendering service in collaboration with a physician
X1 Continuous/broad services: for reporting services by clinicians, who provide the principal care for a patient, with no planned endpoint of the relationship; services in this category represent comprehensive care, dealing with the entire scope of patient problems, either directly or in a care coordination role; reporting clinician service examples include, but are not limited to: primary care, and clinicians providing comprehensive care to patients in addition to specialty care
XS Separate structure, a service that is distinct because it was performed on a separate organ/structure
XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service
Date
Action
Notes
2022-01-01 Changed First appearance of change in codebook.
2022-01-01 Note Grammatical correction.
2021-01-01 Changed First appearance of change in CPT® Code Set.
2020-10-06 Changed Code description changed.
2016-01-01 Changed Description Changed
2011-01-01 Changed Short description changed.
2007-01-01 Changed Code description changed.
1998-01-01 Added First appearance in code book in 1998.
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