What is the diagnostic approach for a female of reproductive age with suspected uterine fibroids?

How to Diagnose Uterine Fibroids

Combined transvaginal and transabdominal ultrasound is the first-line imaging modality for diagnosing uterine fibroids, achieving 90-99% sensitivity for detection and 90% sensitivity with 98% specificity for submucosal fibroids specifically. 1

Initial Clinical Assessment

Begin with a focused gynecologic evaluation including:

• Abdominal examination to assess for enlarged uterus or palpable masses 1
• Speculum examination to visualize the cervix and rule out other causes of bleeding 1
• Bimanual pelvic examination to characterize uterine size, shape, contour irregularities, and mobility 1, 2

The physical examination helps determine if the uterus is enlarged, irregular, or has palpable masses, which guides subsequent imaging decisions. 1

Primary Diagnostic Imaging

Ultrasound as First-Line Modality

Transvaginal ultrasound (TVUS) combined with transabdominal ultrasound (TAUS) is the most useful initial diagnostic approach. 1, 3

• TVUS provides superior resolution for detecting fibroids with 90-99% sensitivity overall 1, 3
• TAUS is essential for large fibroids (>12 cm) or significantly enlarged uteri that exceed the limited field-of-view of transvaginal approach 1
• Color Doppler should be performed routinely to evaluate vascularity patterns and differentiate fibroids from other pathology like arteriovenous malformations 4, 5

Fibroids typically demonstrate peripheral rim vascularity with high-resistance flow patterns (resistance index >0.7) on Doppler imaging. 4

Advanced Ultrasound Techniques

Saline infusion sonohysterography (SIS) improves detection of submucosal fibroids by distending the endometrial cavity, showing good agreement (kappa 0.80) with diagnostic hysteroscopy for classification. 1

• 3D ultrasound demonstrates 87% sensitivity and 100% specificity for diagnosing submucosal leiomyomas compared to hysteroscopy 1
• Ultrasound elastography increases diagnostic accuracy by showing fibroids as well-delineated dark areas (stiff tissue) versus adenomyosis as brighter irregular lesions 1

MRI for Problem-Solving and Surgical Planning

MRI with gadolinium-based contrast is superior to ultrasound for identifying and mapping fibroids, altering management in up to 28% of patients. 1, 3, 5

When to Order MRI

Use MRI when:

• Ultrasound findings are equivocal or limited by body habitus, bowel gas, or multiple fibroids 5
• Detailed preoperative mapping is needed for myomectomy, uterine artery embolization, or focused ultrasound procedures 1, 5
• Differentiation from sarcoma is required in atypical or rapidly growing masses 1

MRI Diagnostic Capabilities

MRI provides comprehensive characterization including:

• Size, number, and precise anatomic location (submucosal, intramural, subserosal) 1, 3
• Signal characteristics on T1 and T2 sequences to identify degeneration types (hyaline, carneous, cystic, fatty, myxoid) 1, 3
• Enhancement patterns to assess vascularity and viability 1, 3
• Differentiation from adenomyosis and endometriosis which cause similar symptoms 1

Diffusion-weighted imaging with ADC values incorporated into an MRI algorithm achieves 83-88% sensitivity and 97-100% specificity for distinguishing fibroids from sarcomas, a critical distinction for surgical planning. 1, 3

Role of CT Imaging

CT has no role in initial fibroid diagnosis but serves specific purposes:

• Post-embolization complications: Use contrast-enhanced CT when patients develop pelvic pain or fever after uterine fibroid embolization to evaluate for infection, hemorrhage, or pelvic venous thrombosis 5
• Calcified fibroids: CT is useful when heavily calcified fibroids cause acoustic shadowing that limits ultrasound visualization 5

CT exposes patients to ionizing radiation without providing the soft-tissue detail of MRI, making it inappropriate for routine evaluation. 5

Diagnostic Algorithm by Clinical Scenario

For Suspected Fibroids (Initial Presentation)

1. Perform pelvic examination to assess uterine size and contour 1, 2
2. Order combined TVUS and TAUS with color Doppler as first-line imaging 1, 3, 5
3. Add saline infusion sonohysterography if submucosal fibroids are suspected and detailed cavity assessment is needed 1

For Preoperative Planning

1. Order MRI with gadolinium contrast to map fibroid location, assess vascularity, and identify degeneration 1, 5
2. Use diffusion-weighted imaging if there is concern for malignancy based on rapid growth or atypical features 1, 3

For Fertility Evaluation

Classify fibroids by location as this determines reproductive impact:

• Submucosal fibroids have the worst prognosis with only 10% pregnancy rates and 4.3% implantation rates 3
• Intramural fibroids reduce pregnancy rates to 16.4% and implantation to 6.4% even without cavity distortion 3
• Subserosal fibroids do not significantly affect fertility with pregnancy rates (34.1%) similar to women without fibroids (30.1%) 3

TVUS achieves 90% sensitivity and 98% specificity for diagnosing submucosal fibroids, the type most critical to identify in fertility patients. 1, 3

Common Diagnostic Pitfalls

Avoid these errors:

• Missing submucosal fibroids by relying on TVUS alone without saline infusion when cavity distortion is suspected 1
• Failing to use TAUS in addition to TVUS, which misses large subserosal or pedunculated fibroids outside the transvaginal field-of-view 1
• Ordering CT as initial imaging, which provides inferior soft-tissue characterization compared to ultrasound and exposes patients to unnecessary radiation 5
• Not performing color Doppler, which is essential for differentiating hypervascular fibroids from arteriovenous malformations 4, 5
• Assuming conventional MRI can exclude sarcoma, when diffusion-weighted sequences with ADC values are required for this distinction 1, 3