Purpose: We aimed to investigate whether transabdominal uterine artery (UtA) pulsatility index (PI) differs between monochorionic (MC) diamniotic and dichorionic (DC) twins and is useful to predict pregnancy complications.
Methods: A total of 406 uncomplicated twin pregnancies (94 MC, 312 DC) were examined at 22+0 -24+6 weeks and compared for demographic characteristics, mean UtA PI, presence of notch, development of preeclampsia, fetal growth restriction (FGR), placental abruption, intrauterine fetal death and preterm delivery. Mann-Whitney and Fisher's exact tests were performed for continuous and categorical variables, respectively. Sensitivity, specificity, positive predictive value, negative predictive value, and likelihood ratio were calculated for mean PI >95th percentile, presence of notch, and presence of either elevated PI or notch.
Results: Median mean UtA PI was 0.68 in DC and 0.75 in MC pregnancies (P = .005). Bilateral notches were observed in one MC pregnancy; unilateral notch was seen in 8 DC (2.6%) and 5 MC diamniotic (5.3%) pregnancies. FGR occurred more frequently in DC twin pregnancies, while intrauterine fetal death in MC. Overall, the sensitivity of the parameters tested was low. Pregnancies with both PI above 95th percentile and presence of notch were all associated with complications, particularly FGR.
Conclusion: MC pregnancies have higher mean UtA PI. UtA screening in twins shows lower performances than in singletons for the detection of complications.
Keywords: Doppler US; monochorionic diamniotic; pregnancy complications; second trimester; uterine artery.
© 2019 Wiley Periodicals, Inc.