Predictive Validity of Fetal Cardiac Axis in First Trimester Ultrasound for Detection of Cardiac and Intrathoracic Abnormalities

Depending on the type of lesion present, fetuses with cardiac and intrathoracic abnormalities have varying prognoses both throughout pregnancy and after delivery.Establishing an accurate prenatal diagnosis is crucial because it enables the couple to receive appropriate counseling, perform prenatal tests like fetal karyotyping, and ultimately in utero fetal therapy, and prepare the baby for delivery in a suitable perinatal facility that can handle the immediate effects on newborns in these situations.These lesions can be progressive, compromising heart function and ultimately IntroductIonThe most prevalent abnormality seen during pregnancy is congenital heart disease or CHD.Between 2010 and 2017, there were 9.4 [95% CI (confidence interval) 8.602-10.253]cases of CHD for every 1,000 live births worldwide.1,2 With this statistic in mind, it is estimated that 2,00,000 infants in India are born with CHD annually.Of these, almost one-fifth are likely to have serious defects requiring intervention during the 1st year of life.3 Fetal thoracic-pulmonary abnormalities vary in frequency depending on the entity.Congenital cystic adenomatoid malformation and bronchopulmonary sequestration (BPS) account for around 40%, congenital diaphragmatic hernia 40%, hydrothorax and other anomalies around 10% 4 of total thoracic-pulmonary abnormalities.The two main ultrasound (USG) views used to assess the thorax are the four-chamber view of the heart and the sagittal view of the diaphragm.At 8 weeks, the embryonic cardiac axis (CAx) is essentially midline, and in the latter part of the first trimester, it is levorotated.By 12 weeks of gestation, the usual leftward fetal heart axis is established.5 The heart typically occupies up one-third of the chest, with a CAx of 45 ± 20° and a cardiac apex that points to the left.Abnormal intrathoracic cardiac position is associated with intrathoracic anomalies.