The role of subendometrial microvascularization and uterine artery blood flow changes in IUD-induced side effects

Abstract

Intrauterine devices (IUDs) are one of the world's most popular methods of reversible birth control. The method is safe, rapidly reversible, inexpensive, highly effective, long-acting and non-hormonal; these attributes make it unique and desirable for many users (Sivin, 2007). The mechanism of IUDs to control birth is still unclear, but whatever the mechanism, copper might enhance inflammatory response and might induce vascular changes of the endometrium and myometrium (Hsu et al., 1976). The most important copper IUDs related side effects are uterine bleeding and/or menstrual pain. These side effects are responsible for a removal rate of 5% to 15% during the first year after IUD insertion. Probably there is a connection between IUD adverse effects and uterine vascularization. However, this association is neither well-known nor well-studied (Jiménez et al., 2006). Color Doppler studies showed an increase in blood flow resistance in the uterus of patients with primary dysmenorrhea (Pirhonen and Pulkkinen, 1995). Other studies showed that there is no change in the uterine artery PI during the mid-luteal phase after the insertion of a copper IUD (Järvelä et al., 1998; Jiménez et al., 2006; Souza and Geber, 2006), but there was a decrease in PI after IUD insertion in patients with increased menstrual pain, suggesting increased blood flow to the uterus in those patients (Jensen, 2005; Souza and Geber, 2006). During menses (first or second cycle days), there was a significant increase in uterine artery blood flow in patients who presented with copper IUD side effects, as indicated by decreased PI and RI (Frajndlich et al., 2000).