What is the best management approach for bilateral 10 cm adnexal (adnexal refers to tissues or structures related to the uterus, such as the ovaries, fallopian tubes, and ligaments) masses in the third trimester of pregnancy?

Management of Bilateral 10 cm Adnexal Masses in the Third Trimester of Pregnancy

For bilateral 10 cm adnexal masses in the third trimester of pregnancy, MRI is the most appropriate next step in management to better characterize the masses before determining the need for surgical intervention. 1

Diagnostic Approach for Large Adnexal Masses in Third Trimester

Initial Assessment

When faced with bilateral 10 cm adnexal masses in the third trimester, several key factors must be considered:

• Size and risk factors: 10 cm masses are associated with higher risk of complications:

  • Torsion risk increases with masses of this size (reported rates of 3-12% with mean size of 10 cm) 1
  • Potential for labor obstruction (reported in 3% of cases with cysts >3 cm) 1
  • Risk of malignancy (though only 2% of adnexal masses in pregnancy are malignant) 1

• Ultrasound characteristics: According to IOTA criteria, masses with the following features raise malignancy concern:

  • Irregular solid tumor
  • Presence of ascites
  • At least 4 papillary structures
  • Irregular multilocular solid tumor with largest diameter ≥10 cm
  • High Doppler blood flow 1

Why MRI is the Preferred Next Step

MRI offers several advantages over serial ultrasound or immediate surgical exploration:

1. Superior tissue characterization: MRI provides better differentiation between benign and malignant lesions without radiation exposure

   • T2-weighted and diffusion-weighted imaging are valuable for characterizing masses without requiring gadolinium contrast (which is avoided in pregnancy) 1

2. Risk stratification: MRI helps determine if immediate intervention is needed or if management can be delayed until delivery

3. Surgical planning: If intervention becomes necessary, MRI provides detailed anatomical information to guide the surgical approach

Management Algorithm

1. For indeterminate masses on ultrasound in third trimester: Proceed with MRI for confirmation and staging 1

2. After MRI assessment:

   • If features suggest benign pathology: Continue surveillance with serial ultrasound until delivery
   • If features suggest malignancy: Consider surgical intervention based on gestational age and maternal-fetal risk assessment

3. Surgical considerations:

   • Timing: If surgery is needed, consider coordinating with delivery planning
   • Approach: Laparoscopy or laparotomy depending on mass characteristics and gestational age
   • Multidisciplinary planning: Involve maternal-fetal medicine and gynecologic oncology

Common Pitfalls and Caveats

• Misinterpreting tumor markers: CA-125 can be markedly elevated in normal pregnancy (up to 2420 U/mL in third trimester), limiting its diagnostic utility 1

• Overlooking torsion: 38-60% of pregnant patients with torsion have normal Doppler flow on ultrasound; maintain high suspicion with acute pain 1

• Unnecessary intervention: Remember that 70% of incidentally identified adnexal masses in pregnancy spontaneously resolve 1

• Delaying necessary treatment: When malignancy is suspected, treatment delay has been associated with worse overall survival 1

• Histological considerations: The most common adnexal masses requiring surgical management in pregnancy are dermoid cysts (32%), endometriomas (15%), and functional cysts (12%) 1

By following this approach with MRI as the next step, you can optimize maternal and fetal outcomes while avoiding unnecessary surgical intervention for what may be benign pathology.