What is the sensitivity and specificity of ultrasound with Doppler (Digital Orthogonal Projection Imaging with Frequency Shift) for diagnosing ovarian torsion?

Ultrasound with Doppler for Ovarian Torsion: Sensitivity and Specificity

Doppler ultrasound has a sensitivity of 80% and specificity of 88% for diagnosing ovarian torsion, according to a meta-analysis of 7 studies with 845 patients. 1

Diagnostic Performance of Ultrasound for Ovarian Torsion

Doppler Ultrasound Findings

• Doppler ultrasound is considered a standard component of pelvic ultrasound evaluation for suspected ovarian torsion 1
• Key Doppler findings in ovarian torsion include:
  • Absent flow or abnormal flow pattern in the ovarian vein (100% sensitivity in a prospective study of 159 patients) 1
  • Whirlpool sign (twisted vascular pedicle) with 90% sensitivity in confirmed adnexal torsion cases 2

Grayscale Ultrasound Findings

• Grayscale ultrasound alone has a sensitivity of 79% and specificity of 76% for diagnosing adnexal torsion (meta-analysis of 12 studies, 1,187 patients) 1
• Important grayscale findings include:
  • Unilaterally enlarged ovary (>4 cm or volume >20 cm³) 2
  • Peripheral follicles (found in up to 74% of cases) 2

Important Clinical Considerations

Limitations of Doppler Ultrasound

• Normal arterial blood flow does not rule out ovarian torsion, as torsion can be intermittent or partial 2, 3
• In some studies, 60% of surgically confirmed ovarian torsion cases had normal Doppler flow 3, 4
• Venous flow abnormalities are more sensitive than arterial flow for detecting torsion 2

Combined Approach

• A combined transabdominal and transvaginal ultrasound approach provides the most comprehensive assessment for suspected torsion 1, 2
• In a study of 13 patients whose only abnormality was absent or abnormal ovarian venous flow with normal grayscale appearance and normal arterial blood flow, 62% had adnexal torsion or subtorsion 1

Alternative Imaging

• MRI has 80-85% sensitivity for ovarian torsion and should be considered when ultrasound findings are inconclusive but clinical suspicion remains high 2
• CT has shown sensitivity ranging from 90-100% and specificity of 85-90% in some studies, but is not recommended as first-line imaging 5

Clinical Implications

• Early detection of ovarian torsion is essential as it may lead to adnexal necrosis and infertility if left untreated 1, 6
• Ovarian torsion should be considered a clinical diagnosis that requires integration of imaging findings with patient presentation 3
• The whirlpool sign on ultrasound is highly specific, with 90% of patients with this sign having adnexal torsion confirmed on laparoscopy 1

Diagnostic Pitfalls

• Relying solely on Doppler flow can lead to missed diagnoses and delayed management 3
• Diagnostic accuracy varies considerably among ultrasound operators (60-100% range) 7
• Ovarian torsion can mimic other conditions such as urinary tract infections or appendicitis 2, 6