What if the right ovary is not clearly visible on imaging?

Management of Non-Visualized Right Ovary on Imaging

When the right ovary is not clearly visible on imaging, additional imaging is generally not necessary as non-visualization of an ovary has a very high negative predictive value (94%) for the absence of ovarian pathology in the short term 1.

Significance of Non-Visualized Ovary

• Non-visualization of an ovary on ultrasound or CT is highly predictive of the absence of ovarian abnormality on short-term follow-up and typically does not require additional imaging to exclude ovarian disease 1.
• A retrospective study found that when an ovary was not visualized on CT, there were no cases of disagreement on ultrasound or subsequent short-term follow-up (negative predictive value 100%) 1.
• For ovaries not visualized on ultrasound, the negative predictive value was 92%, with only rare instances of abnormalities detected on CT 1.

Factors Contributing to Non-Visualization

• The most common imaging findings associated with non-visualized ovaries are uterine fibroids and hemoperitoneum 1.
• Other factors that may contribute to non-visualization include:
  • Patient body habitus
  • Bowel gas
  • Prior pelvic surgery
  • Anatomical variations
  • Technical limitations of the imaging modality

Role of MRI for Non-Visualized Ovaries

• MRI rarely adds additional information when an ovary is not visualized on ultrasound 2.
• The theoretical risk of detecting an ovarian carcinoma on pelvic MRI when an ovary is not visualized on ultrasound ranges from 0 to 1.3% 2.
• Only 6.9% of non-visualized ovaries had non-malignant discordant findings on MRI, with most being physiologic findings (5.2%) such as functional cysts 2.

Clinical Approach to Non-Visualized Ovary

1. Correlate with clinical symptoms:

   • In asymptomatic patients with incidental finding of non-visualized ovary, no further workup is typically needed 1, 2.
   • In patients with acute pelvic pain, consider the possibility of adnexal torsion, especially if there are other concerning clinical features 3.

2. Consider the imaging modality used:

   • If the ovary was not visualized on ultrasound, CT may provide complementary information in some cases 1.
   • Transvaginal ultrasound is generally superior to transabdominal ultrasound for ovarian visualization 3.

3. Evaluate for secondary signs of pathology:

   • Even when an ovary is not visualized, look for indirect signs of pathology such as:
     • Free fluid in the pelvis (beyond physiologic amounts)
     • Adnexal masses
     • Deviation of the uterus
     • Thickening of the fallopian tube 3

Special Considerations

• Pregnancy: In pregnant patients, if adnexal pathology is suspected and ultrasound is inconclusive, MRI is preferred over CT due to lack of radiation exposure 3.
• Reproductive-age women with acute pelvic pain: If gynecological etiology is suspected with negative β-hCG, ultrasound is the initial imaging modality of choice, with CT or MRI reserved for inconclusive cases or if life-threatening diagnosis is considered 3.
• Infertility evaluation: If ovarian assessment is critical (as in polycystic ovary syndrome evaluation), and the ovaries are not adequately visualized with ultrasound, MRI without IV contrast might be useful 3.

Conclusion

Non-visualization of the right ovary on imaging typically does not require additional workup in the absence of concerning clinical features, as it has a high negative predictive value for ovarian pathology. Clinical correlation and consideration of the entire imaging study for secondary signs of pathology are essential for appropriate management.