Authors have reported significant correlation between intertwin CRL discrepancy and outcomes including birthweight discordance, small for gestational age birth weight, preterm delivery, chromosomal abnormalities, structural anomalies, and spontaneous fetal loss [29-32]. Severe CRL discordance (>16%) can be associated with Multiple Gestations US Pregnant Uterus Transvaginal In addition to transabdominal US of the pregnant uterus, TVUS can be performed, especially earlier in gestation, to confirm the number of sacs, to assess chorionicity and amnionicity [24]. When an intertwin membrane is not seen transabdominally, TVUS can be attempted because of superior resolution [9]. Variant 2: Multiple gestations. Monochorionic or dichorionic. First trimester. First trimester ultrasound performed. Next imaging study. In this variant, the patient is known to be carrying a multiple gestation pregnancy and is in the first trimester. The chorionicity has likely been established at a prior US. Often, the amnionicity has also been identified; however, in some cases, definitive confirmation of amnionicity needs to be done. This can be achieved by demonstrating the intertwin membrane at the next imaging study. NT US measurements and first trimester anatomy screening evaluation can be performed at the next imaging study [9,14]. NT measurements for twins are specific screening unique to each twin, whereas cell-free DNA testing techniques cannot separate the genetic information specific to each twin. Documentation of the presence of embryonic cardiac motion and assessment of complications such as early pregnancy failure or subchorionic hemorrhage can also occur. MRI Fetal Without and With IV Contrast Fetal MRI without and with IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without and with IV contrast for evaluation of patients with multiple gestations in the first trimester.
Multiple Gestations. Authors have reported significant correlation between intertwin CRL discrepancy and outcomes including birthweight discordance, small for gestational age birth weight, preterm delivery, chromosomal abnormalities, structural anomalies, and spontaneous fetal loss [29-32]. Severe CRL discordance (>16%) can be associated with Multiple Gestations US Pregnant Uterus Transvaginal In addition to transabdominal US of the pregnant uterus, TVUS can be performed, especially earlier in gestation, to confirm the number of sacs, to assess chorionicity and amnionicity [24]. When an intertwin membrane is not seen transabdominally, TVUS can be attempted because of superior resolution [9]. Variant 2: Multiple gestations. Monochorionic or dichorionic. First trimester. First trimester ultrasound performed. Next imaging study. In this variant, the patient is known to be carrying a multiple gestation pregnancy and is in the first trimester. The chorionicity has likely been established at a prior US. Often, the amnionicity has also been identified; however, in some cases, definitive confirmation of amnionicity needs to be done. This can be achieved by demonstrating the intertwin membrane at the next imaging study. NT US measurements and first trimester anatomy screening evaluation can be performed at the next imaging study [9,14]. NT measurements for twins are specific screening unique to each twin, whereas cell-free DNA testing techniques cannot separate the genetic information specific to each twin. Documentation of the presence of embryonic cardiac motion and assessment of complications such as early pregnancy failure or subchorionic hemorrhage can also occur. MRI Fetal Without and With IV Contrast Fetal MRI without and with IV contrast is not useful as a next imaging study for the evaluation of known or suspected multiple gestations. There is no relevant literature regarding the use of fetal MRI without and with IV contrast for evaluation of patients with multiple gestations in the first trimester.