Bridging Vessel Sign in Uterine Leiomyoma
The bridging vessel sign refers to the presence of curvilinear, tortuous vascular structures (interface vessels) crossing between the uterus and a juxtauterine mass, which is a key imaging feature used to differentiate subserosal/exophytic uterine fibroids from extrauterine tumors, particularly ovarian masses. 1
Imaging Characteristics and Detection
The bridging vessel sign is visualized as:
- Curvilinear tortuous signal void vascular structures on MRI that cross between the uterus and the pelvic mass 2
- Interface vessels connecting the uterine surface to the mass on color Doppler ultrasound 1
This sign is best detected using:
- Color or power Doppler ultrasound as part of standard pelvic imaging 1
- MRI with pre- and post-contrast T1-weighted sequences and T2-weighted imaging 2
Clinical Significance and Diagnostic Performance
The bridging vessel sign is highly specific for subserosal/exophytic uterine leiomyomas:
- Sensitivity: 76.9-78% for diagnosing exophytic uterine leiomyomas 2, 3
- Specificity: 94-98% for differentiating subserosal fibroids from adnexal masses 2, 3
- The sign is present only in exophytic uterine leiomyomas and absent in other adnexal masses such as tuboovarian abscess, endometrioma, or ovarian fibroma 2
Practical Application
When evaluating a pelvic mass of uncertain origin:
On Ultrasound:
- Color Doppler should be routinely included to identify interface vessels between the uterus and juxtauterine masses 1
- The presence of bridging vessels confirms uterine origin rather than ovarian origin 4, 5
On MRI:
- Look for tortuous vascular structures crossing between the uterus and mass on all sequences 2
- Combine with assessment of uterine extension measurements (vertical height >81 mm, uterine length >84 mm support fibroid diagnosis) 3
Clinical Pitfall
The bridging vessel sign is only present in subserosal/exophytic fibroids with a pedunculated or broad-based attachment to the uterine surface. It will not be seen with:
- Intramural fibroids completely within the myometrium
- Submucosal fibroids projecting into the endometrial cavity
- True adnexal masses of ovarian or tubal origin
The sign is particularly valuable when large pelvic masses make it difficult to determine the organ of origin, helping avoid unnecessary surgical exploration by confirming the uterine origin of the mass 1, 4, 5.