19th January 2024

A 22-year-old male presents with a one-day history of a swollen and painful left knee.

A 22-year-old male presents with a one-day history of a swollen and painful left knee. He also has noticed some purulent discharge from his penis for the past few weeks. He is otherwise fit and well, but recalls having unprotected sexual intercourse 3 weeks ago. You suspect he has reactive arthritis.

Which of the following investigation results are most likely to confirm a diagnosis of reactive arthritis? 

Select the SINGLE most appropriate option from the list below. Select ONE option only.