This is a prospective, open-label, single-arm, safety and effectiveness study of Occlusin 500 microspheres in women with symptomatic uterine fibroids.

Prior to entering the study, all patients will undergo pre-study assessments including compliance with inclusion and exclusion criteria, laboratory assessments, pelvic examination, and imaging of the pelvis. Following conventional catheter angiography to confirm catheter placement and the uterine vasculature, each patient will undergo transarterial embolization with Occlusin 500 microspheres.

Inclusion Criteria:

• Premenopausal women with symptomatic uterine fibroids
• Willing and able to provide informed consent
• Fibroids visible by ultrasound or non-contrast magnetic resonance imaging
• Fibroids with a minimum diameter of 4cm for a single fibroid or 3cm where there are 2 or more fibroids; minimum total fibroid burden 33cc
• Documented ovulation by Luteinizing Hormone (LH) testing
• Follicle Stimulating Hormone (FSH) value >40 IU/L within 3 months prior to procedure
• Pelvic examination within 6 months prior to procedure
• Normal Pap smear

Exclusion Criteria:

• Positive pregnancy test
• Uterine size > 20 weeks gestation
• Fibroids that are more than 50% submucosal
• Individual fibroids > 12cm in diameter, or total fibroid burden > 905cc
• Pedunculated subserosal fibroids with an attachment to the uterus less than 50% of the greatest diameter of the fibroid
• Fibroids situated in the cervix
• Abnormally large ovarian arteries
• Uterine pathology other than fibroids
• History of gynecologic malignancy
• Active pelvic infection or history of pelvic inflammatory disease
• Undiagnosed pelvic mass outside the uterus
• History of chemotherapy or radiation to the abdomen or pelvis
• Intra-Uterine Device (IUD) in position
• History of, or ongoing, hemolytic anemia
• Severe cerebrovascular disease defined by a cerebrovascular accident within 6 months of treatment
• Anticoagulant therapy or known bleeding disorder
• Treatment with Gonadotropin Releasing Hormone (GnRH) agonists within the previous 6 weeks
• Received another investigational agent within past 12 weeks
• Compromised hematopoietic function
• Compromised hepatic function
• Compromised renal function
• BMI > 38
• Claustrophobia
• Contraindication to angiography
• Contraindication to magnetic resonance imaging (MRI) or MRI contrast agents
• Allergy to contrast agents
• Allergy to bovine collagen
• Patient desires to become pregnant, or does not agree to contraception during study