There is no one single laboratory test that can definitely diagnose PID. Most cases are diagnosed based on signs and symptoms and other clinical findings from a physical examination. During an examination, the doctor will check for an abnormal discharge from the vagina or cervix or for the presence of an abscess near the ovaries or fallopian tubes. Some cases are diagnosed when a woman is screened for STDs as part of a routine health examination. According to the Centers for Disease Control and Prevention (CDC), PID often goes undiagnosed because the symptoms are nonspecific. Several tests may be performed to help diagnose the condition.
Some tests that may be ordered to determine the cause of PID or rule out other causes of pelvic pain include:
- Chlamydia trachomatis test – to detect chlamydia infection as cause of PID
- Neisseria gonorrhoeae test – to detect gonorrhea infection as cause of PID
- Wet prep – a sample of vaginal/cervical discharge is placed on a slide and examined under a microscope. It is primarily performed to evaluate number of white blood cells (WBCs) in discharge and is often elevated with PID.
- Cervical culture – ordered to help identify the presence of bacteria as the cause of PID
- Urine culture – performed to detect a urinary tract infection
Tests that are not specific for PID may also be done to detect and evaluate associated inflammation and immune response. They include:
- CBC (Complete Blood Count) – an increased white blood cell count may indicate the presence of an infection.
- ESR (Erythrocyte Sedimentation Rate) – nonspecific indicator of inflammation
- CRP (C-Reactive Protein) – nonspecific indicator of inflammation
- Pregnancy test – may be performed to determine whether a woman is pregnant and to help identify ectopic pregnancy
- Physical examination – an evaluation of the cervix, presence of a discharge, and the degree of pain or tenderness; pain associated with movement of the cervix and uterine pain are characteristic of PID. A diagnosis may be made based upon clinical findings.
- Pelvic or transvaginal ultrasound – may be performed to examine reproductive organs organs and may reveal enlarged fallopian tubes or the presence of an abscess
- Laparoscopy – minimally invasive surgery sometimes used to confirm the diagnosis, collect biopsy samples, and evaluate organ status
- CT (computed tomography) scan or MRI (magnetic resonance imaging) scan
- Power Doppler ultrasound – scan that allows evaluation of blood flow and inflammation