For example, population-based data from 18 registries comprise the EUROCAT network. Between 2011 and 2015, EUROCAT (2017) prenatal detection rates for selected fetal anomaliesexcluding genetic conditions-were as follows: anencephaly, 99 percent; spina bifida, 89 percent; hydrocephaly, 78 percent; clet lip/palate, 68 percent; hypoplastic let heart, 87 percent; transposition of the great vessels, 64 percent; diaphragmatic hernia, 74 percent; gastroschisis, 94 percent; omphalocele, 92 percent; bilateral renal agenesis, 94 percent; posterior urethral valves, 79 percent; limb-reduction defects, 57 percent; and clubfoot, 57 percent.
Importantly, however, the overall anomaly detection rate, excluding aneuploidy, was below 40 percent. his relects inclusion of anomalies with minimal or no sonographic detection in the second trimester, such as microcephaly, choanal atresia, cleft palate, Hirschsprung disease, anal atresia, and congenital skin disorders. hese are mentioned because clinicians tend to focus on abnormalities amenable to sonographic detection, whereas those not readily detectable may be equally devastating to families. Therore, evey sonographic examination should include a frank discussion of examination limitations.
Most anomalous neonates are born to women whose pregnancies are otherwise considered low-risk, that is, without an
TABLE 10-6. Components of Standard and Targeted Fetal Anatomic Surveys
Head, face, and neck Lateral cerebral ventricles Choroid plexus Midline falx Cavum septum pellucidum Cerebellum Cistena magna Upper lip Consideration of nuchal skin fold measurement at 15-20 weeks
Four-chamber view of the heart Left ventricular outflow tract Right ventricular outflow tract
Stomach: presence, size, and situs
Cervical, thoracic, lumbar, and sacral spine
Head, face, and neck Integrity and shape of cranium Third ventriclea Fourth ventriclea Corpus callosuma Cerebellar lobes, vermis Brain parenchyma Profile Coronal nose, lips, lensa Palatea, maxilla, mandible, and tonguea Ear pOSition and sizea Orbitsa Neck
Integrity of diaphragm
Abdomen Small and large bowela Adrenal glandsa Gallbladdera Liver Renal arteriesa Spleen° Integrity of abdominal wall
Integrity of spine and overlying soft tissue
Architecture, position, number Hands
Digitsa: number, position aWhen medically indicated (determined on case-by-case basis).
Modified from the American Institute of Ultrasound in Medicine, 2013a; Wax, 2014.
indication for targeted sonography. hus, for standard sonographic examinations, accurate documentation and quality assurance are essential to optimize detection rates. Practice guidelines and standards established by organizations such as the American Institute of Ultrasound in Medicine (2013b) and the Internationl Society of Ultrasound in Obstetrics and Gynecology (Salomon, 2011) have undoubtedly contributed to improvements in anomaly detection rates. Ultrasound practice accreditation is a process ofered by the American Institute of Ultrasound in Medicine and the American College of Radiology that was developed to improve imaging quality and adherence to guidelines. It includes review of images and their storage, ultrasound equipment, report generation, and the qualifications of physicians and sonographers. The Society for Maternal-Fetal Medicine (2013) recommends that whenever possible, obstetrical ultrasound examinations by maternal-fetal medicine sub specialists be performed by accredited practices.
Evaluation of amnionic luid volume is a component of every second-or third-trimester sonogram, and volumes vary with
TABLE 10-7. Indications for Targeted Fetal Anatomical Ultrasound Examination