Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history Multiple Gestations of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. It is usually reserved for problem-solving when an anatomic abnormality is identified. US Assessment for TTTS DC twins with separate placentas do not develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of DC or multichorionic twins. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as a myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43].
Multiple Gestations. Typically, transvaginal imaging is performed only if transabdominal evaluation is considered suboptimal or incomplete and never as the only approach for second trimester anatomy evaluation. If prior history Multiple Gestations of cesarean delivery or uterine instrumentation is present, assessment for placenta accreta spectrum can be performed. MRI Fetal Without and With IV Contrast MRI fetal without and with IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. Gadolinium contrast is usually not administered for fetal indications. MRI Fetal Without IV Contrast MRI fetal without IV contrast does not have a role in growth and antepartum surveillance of DC or multichorionic gestations. It is usually reserved for problem-solving when an anatomic abnormality is identified. US Assessment for TTTS DC twins with separate placentas do not develop TTTS or other complications associated with a single shared placenta. Hence, this evaluation is not useful for growth and antepartum surveillance of DC or multichorionic twins. US Cervix Transvaginal US cervix transvaginal evaluation for antepartum surveillance is useful for assessing cervical length, vasa, and placenta previa. Any cervical pathology, such as a myoma or other masses, that may preclude vaginal delivery should also be assessed. Usually, a transabdominal examination is performed first, followed by transvaginal imaging if the initial evaluation is inadequate. Historically, reports suggested measuring cervical length at each visit to triage for risk of preterm labor. However, more recent literature has questioned the significance and usefulness of this practice, recommending against cervical length measurement after 26 weeks. In twin pregnancies, cervical length measuring <1.5 cm has been shown to be predictive of preterm labor, regardless of management strategies [43].