In a woman with a prior open myomectomy who now presents with a posterior uterine mass and prolonged vaginal discharge, is pelvic MRI indicated?

Pelvic MRI is Strongly Indicated for This Clinical Scenario

In a woman with prior open myomectomy presenting with a posterior uterine mass and prolonged vaginal discharge, pelvic MRI with contrast (if feasible) is the appropriate imaging modality to characterize the mass and guide management. 1, 2

Primary Rationale for MRI

MRI serves as the problem-solving imaging examination of choice for complex pelvic pathology when ultrasound findings are nondiagnostic or inconclusive, due to its superior soft-tissue contrast resolution. 2 This is particularly critical in your patient given:

• The posterior location of the mass makes comprehensive ultrasound evaluation challenging, as US has significant limitations in assessing masses located deep in the pelvis. 3
• The history of prior myomectomy creates altered pelvic anatomy where MRI excels at evaluating postoperative changes and distinguishing recurrent pathology from surgical scarring. 1, 4
• Prolonged vaginal discharge raises concern for infection, necrosis, or malignant degeneration—all of which require tissue characterization that MRI provides. 2

Optimal MRI Protocol

The recommended protocol is pelvic MRI with gadolinium contrast and diffusion-weighted imaging (DWI). 5

• Contrast-enhanced sequences significantly improve diagnostic accuracy (from 69.6% to 98.6% in certain conditions) and are superior to unenhanced imaging for characterizing pelvic masses. 5, 6
• Gadolinium enhancement is essential for distinguishing viable tumor from retained fluid, defining intratumoral architecture, and detecting complications such as abscess formation or fistula. 1, 6
• DWI with ADC mapping should be included as it substantially enhances diagnostic performance for distinguishing benign from malignant lesions. 5
• High-resolution T2-weighted sequences provide detailed anatomical assessment of pelvic organs, surgical changes, and the relationship of the mass to adjacent structures. 2, 4

Diagnostic Capabilities Relevant to This Case

MRI achieves 91% overall accuracy in distinguishing benign from malignant pelvic masses. 1 Specific advantages include:

• Determining the organ of origin (uterine versus adnexal versus extragenital), which may be uncertain with a posterior mass. 1, 7
• Identifying vascular vegetations in cystic masses and ascites, the best indicators of malignancy on MRI. 1
• Detecting postoperative complications including infection, hematoma, or mesh-related issues if any synthetic material was used during myomectomy. 1, 4
• Characterizing the mass composition to differentiate degenerating leiomyoma, sarcomatous transformation, endometriosis, tubo-ovarian abscess, or other pathology. 1, 6

Critical Differential Considerations

Given the clinical presentation, MRI will help distinguish:

• Recurrent or residual fibroid with degeneration (common after myomectomy)
• Leiomyosarcoma (rare but must be excluded given prolonged symptoms)
• Deep infiltrating endometriosis of the posterior compartment, for which MRI has 90.3% sensitivity and 91% specificity. 5
• Tubo-ovarian complex or abscess causing the discharge
• Ovarian pathology mimicking a posterior uterine mass
• Postoperative complications such as pelvic abscess or fistula formation. 1

Common Pitfalls to Avoid

• Do not rely on ultrasound alone when the mass is posterior or deep in the pelvis, as this location significantly limits sonographic evaluation. 3
• Do not omit contrast administration unless contraindicated, as unenhanced MRI has inferior diagnostic performance for characterizing pelvic masses and detecting complications. 1, 6
• Do not skip DWI sequences, which are critical for improving diagnostic accuracy and should be standard in pelvic mass protocols. 5
• Do not attribute symptoms solely to incidental findings without comprehensive correlation—the prolonged discharge suggests active pathology requiring explanation. 5

Timing and Urgency

MRI should be performed promptly given the combination of a mass and prolonged vaginal discharge, which raises concern for infection, necrosis, or malignancy requiring timely diagnosis and intervention. 2 The imaging will provide a comprehensive road map for surgical planning if intervention becomes necessary. 3