A 22-year-old patient suspected of Reiter's syndrome should undergo which laboratory test?

Reiter's syndrome, also known as reactive arthritis, is often associated with a preceding infection, particularly in the genitourinary or gastrointestinal tract. Urethral cultures are crucial in identifying potential pathogens, particularly Chlamydia trachomatis, which has a well-established link to the development of reactive arthritis. By performing urethral cultures, healthcare providers can detect the presence of these infectious agents, which not only aids in establishing a diagnosis but also informs appropriate treatment strategies.

In this context, urethral cultures are particularly relevant because they can directly identify the causative organism responsible for triggering the reactive arthritis, thereby providing essential insight into the patient's condition. Establishing the presence of an infection is critical in understanding the etiology of the patient's symptoms and guiding further management.

While other tests, such as blood cultures and joint aspiration, may have their respective roles in different clinical scenarios, they are not specifically directed at confirming the infection type typically associated with Reiter's syndrome. Urinary analysis may provide general information about kidney function or other urinary issues but does not pinpoint the infectious agents related to the joint symptoms observed in this syndrome.