An intrauterine contraceptive device (IUCD) is one of the most frequently used methods for birth control around the world. However, menorrhagia is among its side effects. Menorrhagia may cause iron deficiency anemia and usually ends by removing the IUCD in the first year after its insertion in many cases .
This prospective cohort study aimed to assess uterine artery, endometrial, and sub-endometrial micro-vascular indices in relation to heavy menstrual bleeding as a predictor of the risk of bleeding before IUCD insertion. Among our studied 110 cases, 42 (38.2%) developed heavy menstrual bleeding.
Basal PBAC score was comparable between women who later developed heavy menstrual bleeding and those who did not, while in follow-up, the PBAC score was significantly higher in heavy menstrual bleeding cases.
In the current study, uterine artery PI and RI significantly decreased with time in heavy and non-heavy menstrual bleeding cases. Still, uterine artery PI and RI (basal and after 3 months) were significantly lower in heavy menstrual bleeding cases and their reduction was significantly higher in heavy menstrual bleeding cases.
Several mechanisms have been proposed to explain IUCD-induced menorrhagia: increased endometrial prostaglandins with subsequent increased capillary permeability and vascularity with decreased platelet activity, and also IUCD induces an inflammatory reaction which causes increased nitric oxide production, a potent vasodilator . Other vascular abnormalities due to abnormal angiogenesis have been proposed; abnormal vasculature resulting from abnormal angiogenesis can have poor contractility and hemostatic dysfunction leading to heavy bleeding and decreased uterine artery vascular impedance .
Indeed, there is some controversy regarding uterine artery PI and RI in IUCD users. Some studies suggest no difference in RI and PI before and after insertion [10,11,12,13], and others demonstrate a PI increase in the midluteal phase, yet still agreed with this study and suggested decreased uterine artery PI after IUCD insertion . Some studies reported no statistical difference between women with IUCD-induced heavy menstrual bleeding and those using IUCD with normal menstruation [15, 16]. Still, many studies found uterine artery RI and PI to be much lower in women with IUCD-induced menorrhagia compared to both: women without IUCD-induced menorrhagia and control women [2, 17,18,19,20].
Some of the studies reporting no difference in uterine artery vascular indices measured them after a relatively short period from IUCD insertion, only 30 days ; this short duration might be insufficient to detect vascular changes by Doppler. This was emphasized in another study which found even increased PI in the participants’ first visit, yet was significantly decreased in their second visit especially in women with increased bleeding scores .
In the current study, sub-endometrium PI and RI significantly decreased with time in heavy and non-heavy menstrual bleeding cases. Sub-endometrium PI and RI (basal and month 3) were significantly lower in heavy menstrual bleeding cases. On the other hand, sub-endometrium VI, FI, and VFI significantly increased with time in heavy and non-heavy menstrual bleeding cases. Sub-endometrium VI, FI, and VFI (basal and month 3) were significantly higher in heavy menstrual bleeding cases. These results are in agreement with several studies [5, 21].
Also, this study showed increased endometrium FI and VFI in both IUCD-induced heavy and non-heavy menstrual bleeding cases which was more evident in women with heavy bleeding. These results are in agreement with previous studies examining the effect of copper IUCD on uterine hemodynamic, but disagreed in women without menorrhagia, where there was no significant difference in the endometrial VI, FI, and VFI before and after IUCD insertion [5, 10, 12, 14, 16, 22]. In the current study, endometrium VFI (≥ 0.18) had the highest significant diagnostic performance in the prediction of heavy menstrual bleeding, followed by sub-endometrium VI (≥ 3.75). This higher diagnostic value of endometrium VFI might be explained by several proposed hypotheses for the mechanism of IUCD-induced bleeding. Among these theories, the low-grade endometrial inflammatory reaction associated with increased prostaglandin synthesis and local vascular changes .
Still, it is difficult to attribute the bleeding only to the presence of lower Doppler indices because low PI values can also be detected in patients without IUCD, and PI values lower than 2 can be detected at various phases of the menstrual cycle as well. Nevertheless, PI values lower than 2 detected at the early phase of the menstrual cycle raise the possibility of an increased bleeding risk. Adding 3D Doppler indices with the suggested cutoff values of both endometrium VFI (≥ 0.18) and sub-endometrium VI (≥ 3.75) might increase the predictability of women liable to IUCD-induced heavy menstrual bleeding. Still, the relatively small number of participants included in this study and the 3-month follow-up might be considered limitations of this study; accordingly, further studies with larger sample size and with longer duration of follow-up, as some cases develop menorrhagia after a longer duration, are needed to further validate this predictive value and its possible clinical application. Also, other studies might investigate the value of uterine arteries and endometrial Doppler blood flow in IUCD-associated pain.