 Introduction/Background Major congenital anomalies occur in 3% to 4% and minor anomalies occur in 7% to 10% of the population [1-3]. Anomalies increase the risk of aneuploidy, syndromes, and poor outcome [2]. Congenital anomalies account for 22.1% of infant deaths, with fetal malformations causing increased morbidity and mortality in the neonatal/postnatal period [3]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Second and Third Trimester Screening for Fetal Anomaly Special Imaging Considerations Transvaginal US The transvaginal US scan can be performed to supplement a transabdominal US scan where a fetal body part is close to the cervix and cannot be visualized transabdominally. Transvaginal US at 12 to 16 weeks can improve evaluation of fetal anatomy in obese women [8,10,21,22]. 3-D and 4-D US Both 3-D and 4-D US have been helpful to further evaluate anatomy, especially facial clefts, spine anomalies such as hemivertebra, and midline brain anomalies such as agenesis of the corpus callosum or abnormalities of the posterior fossa [23,24]. In addition, 3-D and 4-D US [25] can be used as an adjunct to fetal echocardiography [26]. CT CT has an extremely limited role to play in evaluation of the fetus, predominantly restricted to some cases of skeletal anomalies [27]. OR Discussion of Procedures by Variant Variant 1: Second and third trimester screening for fetal anomaly. Low-risk pregnancy. Initial imaging. In the developed world, US is usually performed at least once during pregnancy [28].
Second and Third Trimester Screening for Fetal Anomaly.  Introduction/Background Major congenital anomalies occur in 3% to 4% and minor anomalies occur in 7% to 10% of the population [1-3]. Anomalies increase the risk of aneuploidy, syndromes, and poor outcome [2]. Congenital anomalies account for 22.1% of infant deaths, with fetal malformations causing increased morbidity and mortality in the neonatal/postnatal period [3]. The American College of Radiology seeks and encourages collaboration with other organizations on the development of the ACR Appropriateness Criteria through representation of such organizations on expert panels. Participation on the expert panel does not necessarily imply endorsement of the final document by individual contributors or their respective organization. Reprint requests to: publications@acr.org Second and Third Trimester Screening for Fetal Anomaly Special Imaging Considerations Transvaginal US The transvaginal US scan can be performed to supplement a transabdominal US scan where a fetal body part is close to the cervix and cannot be visualized transabdominally. Transvaginal US at 12 to 16 weeks can improve evaluation of fetal anatomy in obese women [8,10,21,22]. 3-D and 4-D US Both 3-D and 4-D US have been helpful to further evaluate anatomy, especially facial clefts, spine anomalies such as hemivertebra, and midline brain anomalies such as agenesis of the corpus callosum or abnormalities of the posterior fossa [23,24]. In addition, 3-D and 4-D US [25] can be used as an adjunct to fetal echocardiography [26]. CT CT has an extremely limited role to play in evaluation of the fetus, predominantly restricted to some cases of skeletal anomalies [27]. OR Discussion of Procedures by Variant Variant 1: Second and third trimester screening for fetal anomaly. Low-risk pregnancy. Initial imaging. In the developed world, US is usually performed at least once during pregnancy [28].