What is the most appropriate imaging study, MRI or CT scan, for a female patient of reproductive age with pelvic pain likely caused by scar tissue on the ovaries?

Imaging for Pelvic Pain from Suspected Ovarian Scar Tissue

Neither MRI nor CT scan should be your initial imaging study—transvaginal ultrasound is the first-line modality for suspected gynecologic causes of pelvic pain in reproductive-age women, and if ultrasound is nondiagnostic or you need problem-solving, MRI pelvis (not CT) is the appropriate next step. 1

Initial Imaging Approach

• Start with transvaginal ultrasound with Doppler, which is the recommended first-line imaging for any suspected gynecologic etiology of pelvic pain in reproductive-age women 1
• Ultrasound provides excellent visualization of ovarian pathology, adhesions causing architectural distortion, and can identify complications like ovarian torsion or tubo-ovarian abscess 1
• The American College of Radiology guidelines explicitly state there is no relevant literature supporting CT as initial imaging for clinically suspected gynecological causes of pelvic pain 1

When to Order MRI (Second-Line Imaging)

MRI pelvis without contrast is the appropriate advanced imaging modality when:

• Ultrasound findings are inconclusive or nondiagnostic 1
• You need to characterize complex adnexal masses or evaluate deep pelvic pathology 1
• The patient cannot tolerate transvaginal ultrasound 1
• You suspect deep pelvic endometriosis (which can cause ovarian scarring and adhesions), where MRI demonstrates 90.3% sensitivity, 91% specificity, and 90.8% accuracy 1

MRI Advantages for Ovarian/Adnexal Pathology

• Superior soft-tissue contrast allows excellent visualization of fibrosis, adhesions, and architectural distortion that may represent "scar tissue" 2, 3
• MRI can identify T2 hypointense fibrosis (scar tissue) along the ovaries and adnexa, particularly in endometriosis cases 1
• No radiation exposure, which is critical in reproductive-age women 2, 3
• Can differentiate hemorrhagic from non-hemorrhagic lesions using T1-weighted sequences with fat suppression 1

Why CT Should Be Avoided

CT has no role in evaluating suspected ovarian scar tissue or chronic gynecologic pelvic pain:

• The American College of Radiology states there is no relevant literature supporting CT for clinically suspected gynecological etiology of pelvic pain in reproductive-age women 1
• CT exposes reproductive-age women to unnecessary ionizing radiation 2, 3
• CT is reserved for acute presentations with nonspecific symptoms where the differential includes non-gynecologic emergencies (appendicitis, diverticulitis, bowel obstruction) 1, 4
• CT has inferior soft-tissue contrast compared to MRI and cannot adequately characterize subtle fibrotic changes or adhesions 2, 3

Clinical Algorithm

1. Order transvaginal ultrasound with Doppler first 1
2. If ultrasound is diagnostic, proceed with clinical management
3. If ultrasound is nondiagnostic or equivocal, order MRI pelvis without contrast 1
4. Only consider CT if clinical presentation becomes acute with concern for non-gynecologic surgical emergency (perforated viscus, appendicitis, etc.) 1, 4

Common Pitfalls to Avoid

• Ordering CT "because it's faster" ignores evidence-based guidelines and exposes patients to unnecessary radiation without diagnostic benefit for gynecologic pathology 1, 2
• Skipping ultrasound and going straight to advanced imaging wastes resources, as ultrasound will likely provide the diagnosis 1
• Assuming "scar tissue" is not visible on imaging—while adhesions themselves may not be directly visualized, MRI can show architectural distortion, obliteration of fat planes, and fibrotic changes that indicate adhesive disease 1, 3
• Failing to recognize that deep pelvic endometriosis (a common cause of ovarian "scar tissue" and adhesions) requires MRI for accurate diagnosis and surgical planning, with 90.8% accuracy 1, 3