From the Guidelines
Transvaginal ultrasound is the preferred initial imaging modality for evaluating ovarian cysts due to its high sensitivity, lack of radiation, and cost-effectiveness. This approach allows for detailed visualization of cyst characteristics including size, internal components, and vascularity, as demonstrated by a prospective study on 74 patients evaluated with TVUS and MRI, which reported a sensitivity of 83.3% for ovarian torsion, 84% for endometriotic cyst, 88.2% for hemorrhagic cysts, 58.3% for TOA, and 62.5% for dermoid cysts 1. For premenopausal women with simple cysts smaller than 5 cm, follow-up imaging is typically not required as these are usually physiologic and resolve spontaneously. For postmenopausal women, simple cysts smaller than 1 cm generally don't require follow-up, while those between 1-7 cm may need repeat ultrasound in 3-6 months to ensure stability.
- Complex cysts with concerning features such as solid components, thick septations, or papillary projections warrant further evaluation regardless of age, as they may indicate malignancy or other complications.
- When ultrasound findings are inconclusive or concerning for malignancy, pelvic MRI provides superior tissue characterization and can help distinguish between benign and malignant lesions, as supported by the ACR Appropriateness Criteria for postmenopausal acute pelvic pain 2.
- CT scanning is less useful for initial evaluation but may be appropriate when assessing for metastatic disease or complications, such as in the case of ovarian torsion, where CT findings have been described but specific diagnostic accuracy has not been reported to our knowledge 3.
- Doppler ultrasound assessment of blood flow within cysts can provide additional diagnostic information, as increased vascularity may suggest malignancy, and is considered a standard component of a pelvic US examination, particularly in the setting of concern for torsion 2.
From the Research
Imaging Modalities for Ovarian Cysts
- Transvaginal ultrasound is a reliable and cost-effective method for diagnosing most cystic ovarian lesions, especially serous cysts, serous cystadenoma, ovarian carcinoma, and endometrioma 4.
- MRI provides better tissue characterization than Doppler ultrasound or CT-scan and is recommended for indeterminate or complex ovarian ultrasonographic masses 5.
- CT-scan is recommended in the context of acute painful pelvic mass in non-pregnant patients and can be useful in evaluating the extent of ovarian cancer and planning surgical management 5, 6.
Diagnostic Accuracy
- Transvaginal ultrasonography has a high accuracy in diagnosing serous cysts, serous cystadenoma, ovarian carcinoma, and endometrioma, with a kappa value of 0.78, 0.73, and 0.80, respectively 4.
- MRI is superior to CT in lesion characterization, evaluating local extent of tumor, and tumor implants involving the hemidiaphragm and liver surface 6.
Therapeutic Efficacy
- Transvaginal ultrasound-guided aspiration of benign ovarian cysts is a simple, safe, and effective procedure, with an overall recurrence rate of 39.1% 7.
- The use of oral contraceptives after aspiration may increase the success rate of expectant management, with a recurrence rate of 15% in patients who received OCP treatment compared to 47% in those who did not 8.