Recently, research has been evaluating whether screening for congenital heart defects is possible in the first trimester First-trimester screening has been shown to reliably visualize single ventricle lesions as well as transposition of the great arteries.22 Some studies have suggested that the vast majority of major CHDs can be detected during a first-trimester ultrasound if performed by an experienced fetal sonographer and obstetrician as early as 11 to 13 weeks' gestation.23,24 Analysis of first-trimester screening shows that cardiac abnormalities identified in the first trimester were more commonly associated with chromosomal abnormalities (50% to 73%) compared to 17% to 21% in second-trimester screening.22,25 Some authors suggest that early prenatal diagnosis may alter the natural outcome of pregnancies with CHD as it may increase early termination of first-trimester pregnancies However, caution should be exercised when counseling families in the first trimester as it is not always possible to detect cardiac abnormalities in enough detail to provide accurate estimation of the natural history of the suspected lesion Furthermore, some cardiac lesions may not be fully diagnosable in early pregnancy, and firsttrimester screening should not replace second-trimester screening.22 Extracardiac and chromosomal abnormalities are frequently present when CHD is diagnosed prenatally For that reason, when CHD is diagnosed prenatally, consideration should be given to chromosomal testing and secondary anatomic screening if these have not already been completed (Table 89.2).26 Table 89.2 Genetic and Extracardiac Anomalies When There Is a Prenatal Diagnosis of Congenital Heart Disease Congenital Heart Disease AVSD VSD ASD TOF DORV HLHS Truncus arteriosus Transposition of the great arteries Coarctation of the aorta Tricuspid atresia Ebstein anomaly Aortic stenosis Pulmonary stenosis/atresia Chromosomal Anomaly (%) 35–47 37–48 1–3 27 12–45 4–10 14–33 0–3 21–30 2–9 0–3 1–15 4–5 Extracardiac Anomaly (%) 30–50 30–37 16 25–30 19–20 15–21 15–26 12–20 15–34 13 20–26 ASD, Atrial septal defect; AVSD, atrioventricular septal defect; DORV, double-outlet right ventricle; HLHS, hypoplastic left heart syndrome; TOF, tetralogy of Fallot; VSD, ventricular septal defect From Gembruch U, Geipel A Indications for fetal echocardiography: Screening in low- and highrish populations In: Yagel S, et al, eds Fetal Cardiology: Embryology, Genetics, Physiology, Echocardiographic Evaluation, Diagnosis and Perinatal Management of Cardiac Diseases, ed 2 CRC Press Taylor & Francis Group; 2008 Pulse Oximetry Screening The calculated prevalence of critical CHD (requiring intervention in the first year of life) varies from study to study, but based on most recent estimates is approximately 2 infants per 1000 live births, with an overall prevalence of any type of CHD of 9 infants per 1000 births.27 Early diagnosis, particularly of critical CHD, can prevent significant morbidity and mortality Newborns with critical CHD can have profound and rapid deterioration in clinical status in the first days or weeks of life, usually related to closure of the ductus arteriosus and physiologic changes in pulmonary vascular resistance Identification of these newborns prior to hospital discharge, and prior to the development of significant hemodynamic compromise, can allow for timely intervention and medical management such as prostaglandin therapy to maintain ductal patency The relatively high prevalence combined with a period of time where critical CHD can be diagnosed prior to clinical deterioration makes critical CHD an ideal subject for population-based screening Early studies evaluating the use of pulse oximetry in neonates demonstrated that lower-extremity oxygen saturation in infants with critical CHD was lower than age-matched control subjects without critical CHD.28 In determining the most effective screening strategy, sensitivity and specificity should be maximized False-positive results can be a public health concern as they require subsequent testing, which in some settings may delay hospital discharge of the infant or require transfer to another institution, resulting in added familial anxiety, stress, and cost However, increasing specificity at the expense of sensitivity will increase the false-negative rate, possibly resulting in a less effective screening regimen overall The American Heart Association and American Academy of Pediatrics convened a writing group to compose a scientific statement in 2009 to evaluate the evidence on the routine use of pulse oximetry in newborns to detect critical CHD They analyzed ten studies, including over 123,000 infants total Overall, the sensitivity of pulse oximetry screening for critical CHD ranged from 0% to 100% with specificity ranging from 95.5% to 100% False-positive screens were found in a mean of 0.9% of infants with a decrease in the false-positive rate to 0.04% after 24 hours The writing group suggested that a single lower-extremity pulse oximetry reading at an age greater than 24 hours with a threshold of 95% or greater was the most ... Indications for fetal echocardiography: Screening in low- and highrish populations In: Yagel S, et al, eds Fetal Cardiology: Embryology, Genetics, Physiology, Echocardiographic Evaluation, Diagnosis and Perinatal Management of Cardiac Diseases, ed 2... sensitivity will increase the false-negative rate, possibly resulting in a less effective screening regimen overall The American Heart Association and American Academy of Pediatrics convened a writing group to compose a scientific statement in 2009 to evaluate the evidence on the routine use of pulse