Endocervical swabs for Chlamydia trachomatis: Chlamydia is diagnosed using nucleic acid amplification test (NAAT). Alternatively, NAAT can be done on first-catch urine sample or vaginal swabs to test for chlamydia. NAAT has a highest sensitivity and specificity (> 90%) for detection of chlamydia compared with the enzyme immunoassay (60% sensitivity).
Endocervical swab for gonorrhoea should be sent in appropriate transport medium and cultured within 24 hours. If NAAT is used to diagnose Neisseria gonorrhoea, a second confirmatory test is essential using the appropriate culture medium.
Raised white blood count count, erythrocyte sedimentation rate and C-reactive protein are useful measures of the severity of PID.
Electrolytes, liver function and coagulation are only indicated in cases of systemic bacteraemia.
A midstream specimen of urine should be checked to rule-out urinary tract infection as a differential diagnosis.
The absence of endocervical or vaginal pus cells on microscopy or wet-mounted vaginal smear has a good negative predictive value (95%) for the diagnosis of PID, but their presence is non-specific .