This case nicely demonstrates the "bridging vessel" sign, which is a very useful sign in determining the uterine origin of a pelvic mass, with high specificity and sensitivity.

It was first described on Doppler studies, but can also be appreciated on other cross-sectional imaging modalities. 

Multiple tortuous vessels can be seen connecting the uterus to an adjacent pelvic mass, usually a pedunculated subserosal fibroid. This sign will help to differentiate a mass of uterine origin from other pelvic masses originating from the adnexa or bowel. It is best seen in fibroids that are larger than 3 cm.

In this case, the lesion described was initially thought to arise from the adjacent sigmoid colon, until these feeding vessels were identified.