Zohreh Rashidi - Department of Reproductive Imaging, Reproductive Biomedicine Research Center, Royan Institute for ReproductiveBiomedicine, ACECR, Tehran, Iran
Maryam Javam - Department of Reproductive Imaging, Reproductive Biomedicine Research Center, Royan Institute for ReproductiveBiomedicine, ACECR, Tehran, Iran
Firoozeh Ahmadi - Department of Reproductive Imaging, Reproductive Biomedicine Research Center, Royan Institute for ReproductiveBiomedicine, ACECR, Tehran, Iran

Background and Aim : The aim of this manuscript was to describe role of Ultrasound scan in theevaluation of multiple pregnancies.Methods : Manuscripts published at PubMed , Elsevier , Scopus , Google Scholar , SID andoriginal text books were carefully searched with following key words: twin gestation, multiple pregnancy,pregnancy complications and ultrasonography. Several sonograms were also provided to introduce normaland abnormal imaging findings.Results : The number of fetuses and their chorionicity and amnionicity must be determined, as well asmonitoring for complications and anomalies. Finding the placental sites of umbilical cord insertion areimportant because marginal and velamentous insertions increase risk. Multiple pregnancies are associatedwith a high risk of perinatal mortality and morbidity. In addition, compared with singletons, they are atincreased risk of iatrogenic preterm delivery due to the greater incidence of maternal and fetalcomplications. The risk is significantly higher in monochorionic compared with dichorionic pregnancy.Therefore, ultrasound assessment of fetal biometry, anatomy, Doppler velocimetry and amniotic fluidvolume should be used to identify and monitor adverse outcomes such as twin‐ to‐ twin transfusionsyndrome (TTTS), fetal growth restriction (FGR) and etc.Conclusion : The role of ultrasound is crucial in the monitoring of the multiple pregnancies. Therefore,every gynecologist, perinatologist or midwife should be familiar with guidelines of ultrasound evaluationin multiple pregnancies.

twin gestation, multiple pregnancy, pregnancy complications and ultrasonography