In vivo revascularization and tissue effects of uterine artery embolization with starch microspheres in sheep

In uterine artery embolization (UAE) for the treatment of fibroids, nondegradable particles permanently occlude the uterine artery (UA). These particles remain in the vessels and can cause secondary undesirable effects, such as severe pain after embolization and fertility issues. In this prospective experimental study, we aimed to evaluate the angiographic recanalization, local and systemic reactions, and uterine damage occurring after performing UAE with newly developed degradable starch microspheres (DSMs) in sheep.

Under general anesthesia, eight nonpregnant sheep underwent bilateral UAE using DSMs to achieve stasis. Angiographic evaluation was performed on days 1, 3 and 7 after embolization to assess in vivo recanalization. In addition, the angiographic series were scored via a modified embolization score. A postmortem tissue examination was performed to determine whether DSMs and foreign body inflammatory reactions were present and to assess uterine necrosis.

Complete bilateral embolization of the UA and cervicovaginal branches was achieved in all treated animals. Recanalization of the occluded arteries was evident in 25 of 27 arteries during the angiographic evaluation. In all sheep, there were multifocal areas of uterine necrosis, and some uterine vessels contained intraluminal material consistent with DSMs. The average weight of both uterine horns was significantly correlated with both the number of microspheres needed for complete embolization (r = 0.69, ρ<0.01) and the average percentage of necrosis in both uterine horns (r = 0.64, ρ<0.05).

Our findings demonstrated the efficacy of vascular embolization with DSM by inducing ischemic changes in the uterus and subsequent recanalization of previously occluded arteries.