CPT® Code 87164

1. Indications

The dark field examination is indicated for the following conditions and symptoms:

• Syphilis Diagnosis This procedure is primarily performed to identify Treponema pallidum, the causative agent of syphilis, in various specimens.
• Microorganism Identification It is utilized to detect other microorganisms that are best visualized against a dark background, aiding in the diagnosis of certain infections.
• Specimen Collection from Lesions The examination is indicated when there are ulcerative lesions on the skin or mucous membranes that require analysis for potential infectious agents.
• Lymph Node Evaluation It is indicated when there is a need to assess lymph nodes for the presence of infectious organisms, particularly in cases of suspected systemic infections.

2. Procedure

The dark field examination involves several procedural steps to ensure accurate specimen collection and analysis:

• Specimen Collection Depending on the source, the specimen is collected from areas such as the penile, vaginal, oral, skin, or lymph nodes. If the specimen is from a lymph node, a lymph node aspiration biopsy is performed first to obtain the necessary sample.
• Preparation of Skin or Mucous Membrane Lesions For specimens obtained from ulcerative lesions, the lesion is first cleaned and abraded using gauze to prepare the area for specimen collection. This step is crucial to ensure that the sample is representative of the underlying infection.
• Extraction of Serous Transudate After cleaning, the lesion is gently squeezed to extract a drop of serous transudate. This fluid is essential for the examination as it may contain the microorganisms of interest.
• Slide Preparation The extracted drop of serous transudate is placed on a glass slide and covered with a cover slip. This preparation is necessary for microscopic examination.
• Microscopic Examination The prepared slide is examined under a microscope equipped with a dark-field condenser or a phase contrast microscope. This allows for the visualization of motile spirochetes and other microorganisms against the dark background, facilitating accurate identification.

3. Post-Procedure

After the dark field examination, the specimen is analyzed, and results are typically communicated to the requesting physician. Depending on the findings, further diagnostic steps or treatments may be recommended. It is important for healthcare providers to monitor the patient for any signs of infection or complications related to the initial condition that warranted the examination. Follow-up care may include additional testing or treatment based on the results of the dark field examination.