Therapeutic embolization is defined as the intravascular deposition of particulate liquid, mechanical agents, or autologous blood clot to produce intentional vessel occlusion. Embolic vascular occlusion may be performed at any level from large arteries or veins to the capillary beds, and it may be temporary or permanent in nature. Therapeutic embolization has been applied to virtually every vascular territory, to:
- Arrest hemorrhage,
- Occlude congenital and acquired vascular abnormalities,
- Palliate neoplasms, or
- Ablate tissue.
Occlusion of Uterine Arteries Using Transcatheter Embolization or Laparoscopic Occlusion to Treat Uterine Fibroids
Uterine leiomyomata (i.e., fibroids) are extremely common benign tumors that can be located primarily within the uterine cavity (submucosal fibroids) or on the serosal surface of the uterus. Two techniques, transcatheter uterine artery embolization (UAE) and laparoscopic bipolar occlusion of the uterine vessels have been developed to directly devascularize the uterine fibroid and potentially serve as alternatives to hysterectomy.
Treatment for uterine fibroids is usually sought when they are associated with menorrhagia, pelvic pain, urinary symptoms (i.e., frequency), or are suspected to be the cause of infertility. Treatment options include medical therapy with gonadotropin agonists or gestagen suppression or various types of surgical therapy. Hysterectomy is considered the definitive surgical treatment for those who no longer wish to maintain fertility. Various types of myomectomy, which describes removal of the fibroid with retention of the uterus, have also been described. Hysteroscopic myomectomy involves removal of submucosal fibroids using either a resectoscope or a laser. Subserosal fibroids can be removed via an open abdominal or laparoscopic approach. Laparoscopic laser coagulation of uterine fibroids is a unique approach in that the fibroid is not physically removed, but instead multiple (up to 75) laparoscopic laser punctures of the uterine fibroids are performed in an effort to devascularize the fibroid and induce atrophy. Two techniques have been developed that directly devascularize the uterine fibroid by interrupting the uterine arteries. UAE involves selective catheterization of the uterine arteries with injection of embolization material. More recently, laparoscopic bipolar coagulation of the uterine vessels has been investigated as an alternative to UAE.
In April 2000, Embosphere® Microspheres (Biosphere Medical) were cleared for marketing by the U.S. Food and Drug Administration (FDA) through the 510(k) process for hypervascularized tumors and arteriovenous malformations (AVMs). In November 2002, this product was cleared for marketing specifically for use in uterine fibroid embolization. Since that time, several other devices have been cleared for marketing. In 2003, Contour® Emboli PVA (Boston Scientific) was cleared for the embolization of peripheral hypervascular tumors and peripheral AVMs. In March 2004, the Contour SE™ (Boston Scientific) was cleared by the FDA for treatment of uterine fibroids. In December 2008, Cook Incorporated Polyvinyl Alcohol Foam Embolization Particles received FDA marketing clearance for use in uterine fibroid embolization.
No devices have specific clearance or approval from the U.S. Food and Drug Administration (FDA) for laparoscopic bipolar occlusion of the uterine vessels.
Ovarian and Internal Iliac Vein Embolization as a Treatment of Pelvic Congestion Syndrome
Pelvic congestion syndrome is a condition of chronic pelvic pain of variable location and intensity, which is associated with dyspareunia and postcoital pain, and aggravated by standing. The syndrome occurs during the reproductive years, and pain is often greater before or during menses. The underlying etiology is thought to be related to varices of the ovarian veins, leading to pelvic congestion. As there are many etiologies of chronic pelvic pain, the pelvic congestion syndrome is often a diagnosis of exclusion, with the identification of varices using a variety of imaging methods, such as magnetic resonance imaging (MRI), computed tomography (CT) scanning, or contrast venography. For those who fail medical therapy with analgesics, surgical ligation of the ovarian vein has been considered. More recently, embolization therapy of the ovarian and internal iliac veins has been proposed. Vein embolization can be performed using a variety of materials including coils, glue, and gel foam.