Will a Computed Tomography (CT) scan show Pelvic Inflammatory Disease (PID)?

From the Guidelines

CT scans can show findings suggestive of pelvic inflammatory disease (PID), but they are not the first-line imaging test for this condition. According to the most recent evidence from 1, CT may reveal thickened, fluid-filled fallopian tubes, tubo-ovarian abscesses, free fluid in the pelvis, and inflammatory changes in the surrounding fat. However, transvaginal ultrasound is typically preferred as the initial imaging study for suspected PID due to its lack of radiation, better visualization of pelvic structures, and lower cost, as supported by 1.

Some key findings on CT that may suggest PID include:

• Thick-walled fluid density in adnexal location
• Septations within the mass
• Indistinct borders between the uterus and adjacent bowel loops
• Gas bubbles within the mass
• Thickening and anterior displacement of the round ligament

CT is more useful in complicated cases, when ultrasound findings are inconclusive, or when there's concern for other abdominal pathology. MRI offers even better soft tissue resolution for evaluating PID but is less readily available and more expensive. The diagnosis of PID remains primarily clinical, based on symptoms like lower abdominal pain, cervical motion tenderness, and adnexal tenderness, along with laboratory findings such as elevated white blood cell count and C-reactive protein, as noted in 1 and 1. Imaging serves as a supportive tool rather than the definitive diagnostic method for PID.

In terms of sensitivity and specificity, CT evaluation has a sensitivity of 74% to 95% and a specificity of 80% to 90% for the diagnosis of adnexal torsion, as reported in 1. For the diagnosis of tubo-ovarian abscess, pelvic US has a reported sensitivity of 93% and a specificity of 98%, making it a more reliable initial imaging modality for PID, as stated in 1.

From the Research

CT Scan for PID Diagnosis

• A CT scan can be useful in the diagnosis of pelvic inflammatory disease (PID), particularly in cases where the diagnosis is uncertain or when complications are suspected 2, 3.
• CT findings of PID may include thickening of the uterosacral ligaments, pelvic fat stranding, reactive lymphadenopathy, and pelvic free fluid 3.
• CT scans can also help identify complications of PID, such as tubo-ovarian abscess, pyosalpinx, and hydrosalpinx 3, 4.
• However, it is essential to note that a CT scan is not always necessary for the diagnosis of PID, and clinical evaluation and ultrasound may be sufficient in many cases 2, 5.

Advantages of CT Scan in PID Diagnosis

• CT scans can provide a more detailed view of the pelvic anatomy and help identify other potential causes of symptoms, such as appendicitis or diverticulitis 3, 4.
• CT scans can also help guide treatment decisions, particularly in cases where surgery may be necessary 3, 4.

Limitations of CT Scan in PID Diagnosis

• CT scans may not be sensitive enough to detect early stages of PID, and clinical evaluation and ultrasound may be more effective in these cases 2, 5.
• CT scans also expose patients to radiation, which should be taken into consideration when deciding on a diagnostic approach 4.