What is the role of the Ovarian-Adnexal Reporting and Data System (ORADS) Ultrasound (USG) in assessing ovarian lesions?

Role of O-RADS Ultrasound in Assessing Ovarian Lesions

The Ovarian-Adnexal Reporting and Data System (O-RADS) ultrasound risk stratification and management system is essential for standardized assessment of ovarian and adnexal masses, providing consistent risk categorization and evidence-based management recommendations to optimize patient outcomes. 1

O-RADS Framework and Purpose

O-RADS US was developed by the American College of Radiology (ACR) in 2020 to address limitations in existing ovarian lesion classification systems. It provides:

• A standardized lexicon with specific terminology and definitions
• A risk stratification system based on imaging features
• Management recommendations linked to risk categories
• A framework that applies to all classes of risk

The system is designed to reduce ambiguity in ultrasound reports and improve communication between radiologists and clinicians 1, 2.

Risk Categories and Classification System

O-RADS US divides lesions into six risk categories:

1. O-RADS 0: Incomplete evaluation requiring repeat or alternative imaging

2. O-RADS 1: Normal premenopausal ovary (follicles <3cm, corpus luteum)

3. O-RADS 2: Almost certainly benign (<1% risk of malignancy)

   • Simple cysts
   • Classic hemorrhagic cysts <10cm
   • Classic dermoid cysts <10cm
   • Classic endometriomas <10cm
   • Unilocular smooth cysts <10cm
   • Paraovarian cysts
   • Peritoneal inclusion cysts
   • Hydrosalpinges

4. O-RADS 3: Low risk (1-<10% risk of malignancy)

   • Unilocular smooth cysts >10cm
   • Unilocular cysts with irregular walls
   • Multilocular smooth cysts <10cm with color score 1-3
   • Solid smooth lesions with color score 1

5. O-RADS 4: Intermediate risk (10-<50% risk of malignancy)

   • Multilocular smooth cysts >10cm
   • Multilocular irregular cysts
   • Unilocular-solid lesions with 0-3 papillary projections
   • Multilocular-solid lesions with color score 1-2
   • Solid smooth lesions with color score 2-3

6. O-RADS 5: High risk (≥50% risk of malignancy)

   • Unilocular-solid with ≥4 papillary projections
   • Multilocular-solid with color score 3-4
   • Solid smooth with color score 4
   • Solid irregular lesions
   • Ascites or peritoneal nodules/thickening 1

Clinical Implementation and Management Recommendations

Management recommendations are tied directly to risk categories:

• O-RADS 0: Repeat study or alternative imaging
• O-RADS 1: No follow-up needed
• O-RADS 2: No follow-up or optional follow-up in 1 year
• O-RADS 3: Follow-up in 3-6 months, consider US specialist evaluation
• O-RADS 4: Referral to gynecology/oncology specialist
• O-RADS 5: Referral to gynecologic oncology 1, 2

Diagnostic Performance

O-RADS US demonstrates excellent diagnostic accuracy:

• Sensitivity: 95% (95% CI, 91-97%) for detecting malignancy
• Specificity: 82% (95% CI, 76-87%)
• Using O-RADS 4 as threshold: 99% sensitivity, 70% specificity 3, 4

When compared to other systems:

• Similar performance to IOTA Simple Rules (sensitivity 96% vs 93%, specificity 76% vs 82%)
• Similar performance to IOTA ADNEX model (sensitivity 96% vs 96%, specificity 79% vs 78%) 3

Clinical Impact on Patient Management

O-RADS US implementation has significant potential to reduce unnecessary surgeries. A 2024 multicenter study found that 42% of surgically resected ovarian lesions in patients without acute symptoms retrospectively met O-RADS 2 criteria, suggesting these patients could have been managed conservatively with imaging follow-up rather than surgery 5.

Important Considerations and Limitations

• O-RADS US applies to average-risk patients without acute symptoms

• It may require modification for patients with:

  • Significant family history of ovarian cancer
  • BRCA gene mutations
  • Acute symptoms
  • History of ovarian malignancy
  • Pregnancy 1, 6

• Each lesion should be separately characterized in cases of multiple or bilateral lesions

• Management should be driven by the lesion with the highest O-RADS score 1

Practical Implementation Tips

• Use transvaginal ultrasound as the primary approach, supplemented by transabdominal or transrectal approaches as needed
• Measure the largest diameter of the lesion regardless of imaging plane
• Apply the system only to lesions involving ovaries or fallopian tubes (with exceptions for paraovarian cysts and peritoneal inclusion cysts)
• Utilize the O-RADS US smartphone app calculator for efficient categorization 1, 2

O-RADS US represents a significant advancement in standardizing the assessment and management of ovarian and adnexal lesions, with demonstrated ability to accurately stratify malignancy risk and guide appropriate clinical management.