What if an ovary is not visualized on transvaginal ultrasound (TVUS), what further steps should be taken?

Management of Non-Visualized Ovary on Transvaginal Ultrasound

When an ovary is not visualized on transvaginal ultrasound (TVUS), MRI without intravenous contrast should be considered as the next step only if clinical assessment suggests pathology, as non-visualization typically indicates normal ovaries in the absence of other concerning findings.

Understanding Non-Visualization of Ovaries

• Non-visualization of ovaries on TVUS is relatively common, occurring in approximately 20.6% of pelvic ultrasound examinations 1
• Transabdominal ultrasound should be performed in conjunction with TVUS to improve ovarian visualization, especially for ovaries situated in a high position that may be distant from the transvaginal probe 2
• MRI without IV contrast might be useful in the few patients for whom the ovaries are not adequately visualized with ultrasound 2

Clinical Significance of Non-Visualized Ovaries

• The absence of detection of the ovary on pelvic ultrasound is highly predictive of the lack of ovarian abnormality on short-term follow-up (negative predictive value of 94-100%) 3
• In a study of non-visualized ovaries that underwent surgical pathology, 64.6% (31/48) were normal, and 35.4% (17/48) had abnormalities, with the majority being benign subcentimeter lesions 1
• When ovaries are not visualized on ultrasound, the theoretical risk of detecting an ovarian carcinoma on subsequent MRI ranges from 0 to 1.3% 4

Algorithm for Management

1. First-line approach:

   • Ensure both transabdominal and transvaginal approaches have been attempted 2
   • For ovaries in high position, transabdominal ultrasound may provide better visualization 2

2. If ovaries remain non-visualized:

   • In the absence of clinical symptoms or concerning findings, no additional imaging is typically necessary 3, 4
   • For patients with acute pelvic pain, non-visualization of ovaries has high negative predictive value (NPV 100% on CT, 92% on ultrasound) for excluding ovarian pathology 3

3. Consider MRI without IV contrast when:

   • Clinical assessment suggests pathology despite non-visualization 2
   • Evaluation of ovarian reserve is needed in patients with infertility 2
   • Patient is obese or has other factors limiting ultrasound visualization 2

4. Special considerations:

   • In pediatric patients with suspected adnexal torsion, non-visualization of ovaries with a non-distended bladder has a negative predictive value of 100% and specificity of 99.4% for excluding torsion 5
   • In postmenopausal women, non-visualization may be due to ovarian atrophy, with average size of non-visualized ovaries being 0.7 x 0.4 cm 6

Common Pitfalls and Caveats

• Relying solely on transvaginal approach without attempting transabdominal imaging may miss ovaries in high position 2
• The presence of peritoneal carcinomatosis should prompt further investigation even with non-visualized ovaries, as this was associated with malignant ovarian lesions in one study 1
• In patients with suspected polycystic ovary syndrome (PCOS), MRI without IV contrast can provide reliable ovarian volume assessment when TVUS is limited, though follicle counts had only moderate interobserver agreement 2
• Non-visualization of ovaries should not be confused with absence of ovaries - careful review of surgical history is essential to confirm expected presence of both ovaries 7