EP09.105: Persistent left superior vena cava: prenatal diagnosis and associations

To evaluate the prevalence and clinical significance of the prenatal diagnosis of LSVC and its relationship with other cardiac and extracardiac anomalies. Retrospective, descriptive study, in the Fetal Medicine Unit of the Clinical Hospital of the University of Chile, between 2005 and 2022. The data was obtained from the ASTRAIA® software database. The following variables were analysed: maternal and perinatal demographics, reason for consultation or referral, gestational age at diagnosis, cardiac and extracardiac anomalies and chromosomal abnormalities associated with LSVC. A total of 44,728 pregnancies were evaluated during the study period, identifying 19 cases of LSVC. Prevalence per period was: 0.01% (2005-2009), 0.04% (2010-2014), 0.06% (2015-2019) and 0.06% (2020-2022). Referrals for re-evaluation were 73.6% (n = 14), of which 42.1% (n = 8) were due to suspected congenital heart disease (CHD). Average maternal age was 31 years (±6DS); weight and BMI being 64kg (±13DS) and 25 (±5DS). Average gestational age at diagnosis was 28.4 weeks (±4.7DS). Isolated LSVC were 31.5% (n = 6). Association with CHD was 47.4% (n = 9) and with extracardiac anomalies 52.6% (n = 11) of cases. Chromosomal study was positive in 6 of 7 cases (other anomalies and a high suspicion of aneuploidy). Average gestational age at delivery was 36.7 weeks (±4.9DS), Caesarean section was the most frequent delivery route, and average birthweight was 3137 grams (±760.1DS). The prevalence of LVSC was much lower than expected, but with a progressive increase in relation to the use of the three-vessel view, highlighting the importance of systematic screening views for CHD. Despite this, the data presented here are consistent with the literature, so in cases of suspected LVSC, it is mandatory to perform a thorough morphological examination and echocardiography. Routine chromosomal study is not suggested in isolated cases; but, it is strongly suggested in cases with other anomalies. The actual efficiency of this marker should be established in prospective studies in unselected populations.