CPT® Code 87164

A dark field examination, also known as dark field microscopy, is a specialized diagnostic procedure utilized to identify microorganisms in various specimens. This examination can be performed on samples obtained from multiple sources, including penile, vaginal, oral, skin, or lymph nodes. The primary purpose of this test is to detect specific microorganisms, such as Treponema pallidum spirochetes, which are responsible for syphilis. The unique aspect of dark field microscopy is its ability to visualize these microorganisms against a dark background, enhancing their visibility. In cases where the specimen is derived from a lymph node, a lymph node aspiration biopsy is conducted prior to the dark field examination. For specimens collected from ulcerative lesions on the skin or mucous membranes, the procedure involves cleaning and abrading the lesion with gauze, followed by applying pressure to extract a drop of serous transudate. This drop is then placed on a glass slide, covered with a cover slip, and examined under a microscope equipped with a dark-field condenser or a phase contrast microscope to assess the presence of motile spirochetes. The CPT® code 87164 is designated for the dark field examination that includes specimen collection, while 87166 is used when the laboratory conducting the test does not collect the specimen itself.