What is the role of imaging in the emergency department for diagnosing ovarian torsion?

From the Guidelines

Ultrasound is the first-line imaging modality for suspected ovarian torsion in the emergency department, with a comprehensive pelvic ultrasound using both transabdominal and transvaginal approaches being the preferred initial assessment. This approach is supported by the American College of Radiology, which recommends a combined transabdominal and transvaginal ultrasound for pelvic imaging when an obstetrical or gynecological etiology is suspected 1. The ultrasound should evaluate for signs of ovarian torsion, including an enlarged ovary (>4cm), presence of ovarian masses or cysts, decreased or absent Doppler blood flow to the affected ovary, and free fluid in the pelvis.

Key findings on ultrasound that suggest ovarian torsion include:

• Ovarian tissue edema, although this has a low sensitivity of 21% 1
• Absence of intraovarian vascularity, with a sensitivity of 52% and specificity of 91% 1
• Absence of arterial flow, with a sensitivity of 76% and specificity of 99% 1
• Absence or abnormal venous flow, with a sensitivity of 100% and specificity of 97% 1
• A unilaterally enlarged ovary with central afollicular stroma and multiple uniform 8 to 12 mm peripheral follicles, found in up to 74% of cases 1

It's essential to note that while ultrasound is a valuable diagnostic tool, it should complement but not replace clinical judgment, as ovarian torsion remains primarily a clinical diagnosis. If ultrasound is inconclusive but clinical suspicion remains high, surgical consultation should not be delayed, and further imaging with CT or MRI can be considered as second-line options. The goal is to rapidly diagnose and intervene in cases of ovarian torsion to prevent ovarian necrosis and loss of the ovary.

In cases where pelvic inflammatory disease (PID) is suspected, ultrasound can also be useful in detecting signs such as bilateral adnexal masses, thick walls, and well-vascularized masses at color Doppler 1. However, the primary focus in the emergency department should be on promptly identifying and managing ovarian torsion due to its urgent nature and potential for severe complications.

From the Research

Emergency Department Imaging for Ovarian Torsion

• Ovarian torsion is a surgical emergency that can be challenging to diagnose due to non-specific clinical presentations, such as abdominal pain, nausea, and vomiting 2.
• Imaging modalities play a crucial role in diagnosing ovarian torsion, with ultrasonography being the first-line imaging modality of choice 3, 4.
• Ultrasound features of ovarian torsion include ovarian enlargement, edema, and absence of arterial and venous flow, which can be demonstrated using color and spectral Doppler examination 5, 4.
• Computed Tomography (CT) findings, such as ovarian enlargement, adnexal mass, and twisting of the vascular pedicle, can also be useful in diagnosing ovarian torsion, especially in cases where CT is the initial imaging test 3, 6.
• Magnetic Resonance Imaging (MRI) can be helpful in cases where the diagnosis remains unclear, particularly in young or pregnant patients with equivocal sonographic findings, as it provides excellent soft tissue contrast without ionizing radiation 6.

Imaging Modalities for Ovarian Torsion

• Ultrasonography:
  • First-line imaging modality of choice 3, 4
  • Can demonstrate ovarian enlargement, edema, and absence of arterial and venous flow 5, 4
• Computed Tomography (CT):
  • Can be useful in diagnosing ovarian torsion, especially in cases where CT is the initial imaging test 3, 6
  • Findings include ovarian enlargement, adnexal mass, and twisting of the vascular pedicle 3, 6
• Magnetic Resonance Imaging (MRI):
  • Helpful in cases where the diagnosis remains unclear, particularly in young or pregnant patients with equivocal sonographic findings 6
  • Provides excellent soft tissue contrast without ionizing radiation 6

Importance of Early Diagnosis

• Early diagnosis of ovarian torsion is critical to preserve ovarian function and prevent permanent irreversible damage 3, 2.
• Prompt diagnosis and treatment can improve clinical outcomes and preserve the ovary and/or fallopian tube 2, 6.