Are bilateral 10 cm adnexal (adnexal refers to structures around the uterus, such as the ovaries, fallopian tubes, and ligaments) masses in the third trimester of pregnancy more likely to be benign or malignant?

Bilateral 10 cm Adnexal Masses in Third Trimester Pregnancy: Benign vs. Malignant Assessment

Bilateral 10 cm adnexal masses in the third trimester of pregnancy are more likely to be benign, with all reported cases of bilateral masses in pregnancy being benign according to the literature. 1

Epidemiology and Risk Assessment

• Approximately 2% of adnexal masses in pregnancy are malignant 1
• Bilateral adnexal masses have been reported in up to 4% of cases during pregnancy 1
• Of the published reports specifically examining bilateral masses in pregnancy, all were found to be benign 1

Characteristics of Third Trimester Adnexal Masses

Common Benign Etiologies:

• Dermoid cysts (32% of surgically removed masses) 1
• Serous and mucinous cystadenomas (19%) 1
• Endometriomas (15%) 1
• Functional cysts (12%) 1
• Pregnancy-specific conditions:
  • Hyperreactio luteinalis (bilateral ovarian enlargement with multiple peripheral cysts, typically in third trimester) 1
  • Luteomas (can mimic neoplasms, appear as heterogeneous irregular solid masses) 1

Risk Assessment Using IOTA Criteria:

The International Ovarian Tumor Analysis (IOTA) criteria validated in pregnancy show that:

• Malignant features include:

  • 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

• Benign features include:

  • Unilocular cyst
  • Solid components <7 mm
  • Acoustic shadows
  • Smooth multilocular tumor with largest diameter <10 cm
  • No Doppler blood flow 1

Clinical Implications and Management

Risk Considerations:

• Size matters: Masses with mean size of 10 cm have higher risk of torsion (3-12% in pregnancy) 1
• Bilateral masses of 10 cm in third trimester may present risks for:
  • Labor obstruction (reported in 3% of cases with cysts >3 cm) 1
  • Pain requiring hospital admission (2-10% of patients) 1

Management Algorithm:

1. Ultrasound assessment using validated scoring systems (IOTA has 92% sensitivity, 69% specificity for malignancy in pregnancy) 1
2. MRI confirmation for indeterminate masses or when malignancy is suspected 1
3. Surgical intervention considerations:
   • Required for symptomatic masses (torsion, rupture)
   • Recommended for masses with high suspicion for malignancy 1
   • Timing should balance maternal and fetal risks

Special Considerations for Bilateral 10 cm Masses

• Bilateral masses of this size in the third trimester warrant careful evaluation but are statistically more likely to be benign 1
• Hyperreactio luteinalis should be strongly considered as it typically:
  • Presents as bilateral ovarian enlargement in the third trimester
  • Is caused by ovarian hyperstimulation by hCG
  • Spontaneously regresses after delivery 1

Pitfalls to Avoid

1. Over-reliance on CA-125: This marker can be significantly elevated in normal third trimester pregnancy (up to 2420 U/mL reported) 1
2. Assuming malignancy based solely on size: While 10 cm is a threshold in IOTA criteria, bilateral masses in pregnancy have consistently been reported as benign 1
3. Missing torsion: 38-60% of pregnant patients with torsion have normal Doppler flow on ultrasound 1
4. Unnecessary intervention: 70% of incidentally identified adnexal masses in pregnancy spontaneously resolve 1, with specific conditions like hyperreactio luteinalis typically resolving after delivery

While vigilance for malignancy is important, the evidence strongly suggests that bilateral 10 cm adnexal masses in the third trimester of pregnancy are more likely to be benign, with specific consideration for pregnancy-related conditions such as hyperreactio luteinalis.