What type of ultrasound is recommended to evaluate the ovaries?

Transvaginal Ultrasound is the Preferred Method for Evaluating Ovaries

Transvaginal ultrasound is the recommended first-line imaging modality for evaluation of the ovaries due to its superior visualization capabilities and ability to characterize ovarian structures in detail. 1

Primary Imaging Recommendations

• Transvaginal ultrasound should be the initial imaging modality of choice for ovarian evaluation as it provides the best visualization of ovarian structures and allows for accurate assessment of follicle counts and ovarian volume 1

• When transvaginal ultrasound is not feasible (patient preference, virginal status), transabdominal ultrasound can be performed, though it is less reliable for detailed follicle counts and primarily useful for assessing ovarian volume 1

• Color Doppler ultrasound can provide additional information about ovarian vascularity when needed, particularly when evaluating for malignancy, but is not routinely required for basic ovarian assessment 1, 2

Specific Clinical Scenarios

For General Ovarian Assessment:

• Transvaginal ultrasound allows for detailed evaluation of:
  • Ovarian volume (normal <10ml) 1
  • Follicle number and size 1
  • Ovarian morphology and detection of cysts or masses 1
  • Endometrial thickness and appearance (as part of comprehensive evaluation) 1, 3

For Polycystic Ovary Syndrome (PCOS) Evaluation:

• Transvaginal ultrasound with 8MHz frequency transducer is preferred for detecting polycystic ovarian morphology (PCOM) 1, 3
• Current diagnostic threshold for PCOM is ≥20 follicles per ovary and/or ovarian volume ≥10ml 1, 3
• Ultrasound is not recommended for PCOS diagnosis in adolescents with gynecological age <8 years due to high incidence of multifollicular ovaries in this age group 1, 3

For Ovarian Cancer Screening/Evaluation:

• Transvaginal ultrasound is the most extensively evaluated imaging modality for ovarian cancer assessment 1
• When evaluating suspicious ovarian masses, transvaginal ultrasound with Doppler assessment provides the highest sensitivity (100%) while Doppler alone offers maximum specificity (96.29%) 2
• For indeterminate ovarian masses on ultrasound, MRI provides additional characterization 1

Important Considerations and Limitations

• Ovarian visualization can be challenging in certain circumstances:

  • During pregnancy, transvaginal ultrasound visualizes both ovaries in 95% of first-trimester patients, while transabdominal ultrasound visualization decreases significantly with advancing gestational age 4
  • Non-visualization of an ovary on ultrasound has a high negative predictive value (92%) for absence of ovarian pathology 5

• For comprehensive evaluation of suspected ovarian cancer, ultrasound findings should be correlated with serum CA-125 levels and clinical assessment 1

• While MRI and CT can evaluate ovaries, they are not first-line for routine ovarian assessment:

  • MRI is reserved for characterizing indeterminate adnexal masses found on ultrasound 1
  • CT has limited ability to evaluate adnexal structures and distinguish between benign and malignant ovarian lesions 1, 6

Documentation Recommendations

• Ultrasound reports evaluating ovaries should include:
  • Date of last menstrual period
  • Transducer frequency and approach used
  • Total follicle number per ovary (2-9mm)
  • Three dimensions and volume of each ovary
  • Endometrial thickness and appearance
  • Any other ovarian or uterine pathology 1, 3

Transvaginal ultrasound remains the most cost-effective and accurate method for evaluating most ovarian conditions, providing excellent visualization without radiation exposure 1, 6.