Essential investigations
| STI tests |
|---|
| NAAT for Chlamydia trachomatis and Neisseria gonorrhoeae (vulvo-vaginal sample in women, urine in men; throat and rectal samples depending on sexual history and symptoms). |
| If N gonorrhoeae NAAT is positive further samples for culture confirmation and sensitivity are required. |
| NAAT for Mycoplasma genitalium if available, particularly important for men with urethritis (endocervical sample in women, urine in men). |
| Urethral (men) or endocervical (women) samples for Gram staining and culture if genital symptoms are present. |
| HIV antibody test (fourth generation – antigen/antibody) |
| Synovial fluid analysis |
| Cell count, Gram stain, crystals. |
| Culture (where septic arthritis is suspected). |
| Acute phase response |
| Erythrocyte sedimentation rate or C-reactive protein. |
| Other |
| Full blood count. |
| Urinalysis. |
NAAT = nucleic acid amplification test; STI = sexually transmitted infection.