Diagnosis of Fetal Cardiac Malformation in the First Trimester
First trimester ultrasound is widely accepted as an effective screening tool for trisomy 21 and other chromosomal abnormalities. This examination also provides an opportunity to detect many structural abnormalities between 11+0 and 13+6 weeks
Indeed, recent data suggests that up to 80% of major abnormalities may be detected at this time [1]. With regard to cardiac diagnosis an increased nuchal translucency provides unique clue to the diagnosis of cardiac malformation; a clue that is not present later in the pregnancy either at the routine mid trimester screening scan or in the 3rd trimester and this applies to both aneuploid and euploid fetuses. Indeed, 5% of all patient who present with an increased nuchal translucency and following testing have normal chromosomes will be found later to have a major cardiac defect. The greater the nuchal translucency, the greater the chance of cardiac malformation ( 2.5% have cardiac anomalies when the NT is 2.5-34mm and 7% when the NT is> 3.5mm [2]
An outline of the sonographic assessment of the normal and abnormal heart at 11-14 weeks will be presented.
[1] Detailed screening for fetal anomalies and cardiac defects at the 11-13-week scan Becker R et al. Ultrasound Obstet Gynecol. 2006 Jun;27(6):613-8.
[2] Incidence of major structural cardiac defects with increased nuchal translucency but normal karyotype. Ghi et al. Ultrasound Obstet Gynecol 2001; 18(6): 610-4.