Follow-Up for a 5.6 cm Intramural Fibroid
For a 5.6 cm intramural fibroid, MRI is recommended for better characterization, followed by clinical surveillance with repeat imaging at 6-12 month intervals to monitor for growth, particularly in premenopausal women where rapid enlargement may indicate malignancy. 1, 2
Role of MRI in Characterization
MRI provides superior delineation of fibroid location, size, and number compared to ultrasound and can differentiate fibroids from adenomyosis and endometriosis, which is particularly valuable for a lesion of this size. 1, 3
MRI is especially useful when multiple fibroids are present or when the relationship between fibroids and surrounding structures needs better understanding, as is often the case with larger intramural fibroids. 2
The imaging features of fibroids can vary greatly on MRI, particularly with degeneration, making it the preferred modality for complete characterization. 1
Surveillance Strategy
Repeat imaging at 6-12 month intervals is recommended to assess for fibroid growth, particularly in premenopausal women where rapid growth raises concern for leiomyosarcoma (estimated risk 2.94 per 1,000). 2
If the patient is asymptomatic and the fibroid remains stable in size, continued surveillance with annual pelvic ultrasound is appropriate. 1, 3
Assessment should include evaluation for symptoms such as heavy menstrual bleeding (requiring complete blood count to assess for anemia), pelvic pain, bulk symptoms, and reproductive dysfunction. 1, 2
Clinical Significance of Size
Intramural fibroids >4 cm may negatively impact fertility even without cavity distortion, which is clinically relevant for this 5.6 cm lesion if the patient desires future pregnancy. 4, 5
Research demonstrates that patients with intramural fibroids >4.0 cm had lower pregnancy rates compared to those with fibroids ≤4.0 cm, suggesting this size threshold has clinical implications. 5
Larger intramural fibroids (>4 cm) show more pronounced volume reduction after treatment interventions like uterine artery embolization, with a positive correlation between pretreatment volume and percentage reduction. 6
Additional Workup Considerations
Endometrial biopsy should be considered if abnormal uterine bleeding is present, particularly in perimenopausal women, to rule out endometrial pathology. 2
Pregnancy testing is necessary to rule out pregnancy as a cause of uterine enlargement. 2
If saline infusion sonohysterography (SIS) has not been performed, it should be considered to definitively exclude any submucosal component or endometrial cavity distortion, as this would significantly alter management. 2, 3
Common Pitfalls to Avoid
Incomplete evaluation of the entire uterus in cases of what appears to be a solitary fibroid—MRI can identify additional fibroids missed on ultrasound. 2, 3
Failing to assess for cavity distortion, as even intramural fibroids can have a submucosal component that affects fertility and bleeding patterns. 3
Inadequate follow-up in premenopausal women, where failure to detect rapid growth may delay diagnosis of leiomyosarcoma. 2
Relying solely on transvaginal ultrasound for a fibroid of this size without complementary transabdominal ultrasound or MRI, which may underestimate the true dimensions. 2, 3