This is a very interesting phenomenon, and can be explained by several mechanisms.

  • Fibroids have much more vessels and blood supply than normal uterine tissue. Thus, when particles are injected into the main uterine artery, most of them are “sucked” by the fibroids. As a result, the majority of the particles go into the fibroid vessels while only a small part of them go into the normal uterine vessels.
  • Since fibroid tissue is used to a lot of blood supply, it is very sensitive to changes in blood circulation. As a result, when its vessels are occluded it rapidly becomes dead. In contrast, normal uterine tissue is used to a low blood supply, and is not very sensitive to changes in circulation. Therefore, it will survive after UFE.
  • Fibroids have blood vessels that originate only from the main uterine arteries. Thus, when these vessels are occluded, they die in a short time. By contrast, normal uterine tissue have other blood vessels, besides their own arteries, from the surrounding organs such as ovaries, tubes and vagina. Thus, when the main uterine arteries are occluded, the normal uterine tissue continue to have blood from other vessels and survive after UFE.
  • Following UFE, the main uterine arteries generally reopen after some time. This has been demonstrated in some studies using MR angiography. The reopened arteries start to feed the normal live uterine tissue again, but they can not feed the fibroids because they are already dead.

In conclusion, owing to the combined effects of these factors, fibroids in the uterus become dead after UFE, while the normal uterine tissue survives and keeps its normal function.