OC15.01: How good is the obstetric routine cardiac scan?

Abstract

The objective was to evaluate the detection rate of congenital heart defects (CHD) in a non-selected population and to follow outcome after diagnosis. All pregnant women delivering at our hospital between February 1991 and December 2001 were registered prospectively. Of those, 29 460 (98%) fetuses had a prenatal ultrasound at our center. The routine fetal examination at approximately 18 weeks included the four-chamber view and the great arteries of the fetal heart. The follow-up period was 2–13 years. Of 97 critical CHDs, 55 (57%) were detected prenatally: 16% (9/55) prior to, 66% (36/55) at and 18% (10/55) after the routine scan. Forty-four percent (19/43) of the isolated CHDs, 67% (36/54) of those with associated malformations and 48% (11/23) of the isolated ductal dependent CHDs were detected. Thirty-eight percent (37/97) had an abnormal karyotype. Of the 55 critical CHDs detected, 44% (24) of the pregnancies with lethal/serious fetal malformations were terminated, 15% (8) died in utero, 42% (23) were born alive, 27% (15) were still alive after 2 years. Of the 42 CHDs detected postnatally, 2% (1) were terminated for other reasons, 98% (41) born alive and 81% (34) were still alive after two years. Prenatal detection of CHD is still a challenge with 57% detection rate only. Isolated defects are detected less frequently. To improve the results, the great arteries have been added to the fetal heart examination in addition to the four chamber view, increasing the detection rate to some extent, but not as much as expected. Our data suggest that implementation of additional views might not give the expected results as long as the basic views are not fully exhausted. The importance of a stepwise introduction to the fetal heart examination still seems fundamental to the success in fetal heart scanning, underlining the importance of mastering the first step, the four-chamber view, before the next step is considered, emphasizing the need for additional training.