Multiple Gestations Fetal Doppler can include umbilical artery (UA), middle cerebral artery (MCA), and ductus venosus. At some institutions, all 3 are performed together as an obstetric Doppler evaluation. Ductus venosus evaluation is performed as a part of fetal echocardiography evaluation. Fetal imaging with MRI is being increasingly used for pregnancies complicated by congenital anomalies or complications related to MC gestations [17,18]. Both neurologic and nonneurologic indications exist for fetal imaging. In MC twins, fetal MRI is helpful for assessing intracranial injury that may occur following spontaneous single fetal demise or after an in utero intervention such as laser ablation of intertwin vascular connections [18,19]. Details on risk to the fetus, guidelines on screening for pregnancy, minimizing radiation exposure, and risk assessment can be found in the ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation [20]. Gadolinium contrast is a relatively contraindicated in pregnancy, which is discussed in detail in the ACR Manual on Contrast Media [21] and the ACR Gadolinium Pregnancy Screening Statement [22]. Most importantly, there are currently no established indications for using gadolinium for MRI evaluation of twin pregnancy or fetal conditions, in general. OR Discussion of Procedures by Variant The variants discussed are presented in approximate order of gestational age. This discussion is almost entirely focused on twin pregnancies because twins represent 98% of multiple gestations, and the vast majority of data relate to twins. It is recognized that higher risks occur in the setting of triplets and higher-order multiples [23]. Variant 1: Known or suspected multiple gestations. Monochorionic or dichorionic. First trimester. Initial imaging. In this variant, the patient is clinically known or suspected to be pregnant with twins or higher order multiples.
Multiple Gestations. Multiple Gestations Fetal Doppler can include umbilical artery (UA), middle cerebral artery (MCA), and ductus venosus. At some institutions, all 3 are performed together as an obstetric Doppler evaluation. Ductus venosus evaluation is performed as a part of fetal echocardiography evaluation. Fetal imaging with MRI is being increasingly used for pregnancies complicated by congenital anomalies or complications related to MC gestations [17,18]. Both neurologic and nonneurologic indications exist for fetal imaging. In MC twins, fetal MRI is helpful for assessing intracranial injury that may occur following spontaneous single fetal demise or after an in utero intervention such as laser ablation of intertwin vascular connections [18,19]. Details on risk to the fetus, guidelines on screening for pregnancy, minimizing radiation exposure, and risk assessment can be found in the ACR-SPR Practice Parameter for Imaging Pregnant or Potentially Pregnant Adolescents and Women with Ionizing Radiation [20]. Gadolinium contrast is a relatively contraindicated in pregnancy, which is discussed in detail in the ACR Manual on Contrast Media [21] and the ACR Gadolinium Pregnancy Screening Statement [22]. Most importantly, there are currently no established indications for using gadolinium for MRI evaluation of twin pregnancy or fetal conditions, in general. OR Discussion of Procedures by Variant The variants discussed are presented in approximate order of gestational age. This discussion is almost entirely focused on twin pregnancies because twins represent 98% of multiple gestations, and the vast majority of data relate to twins. It is recognized that higher risks occur in the setting of triplets and higher-order multiples [23]. Variant 1: Known or suspected multiple gestations. Monochorionic or dichorionic. First trimester. Initial imaging. In this variant, the patient is clinically known or suspected to be pregnant with twins or higher order multiples.