P05.10: Perinatal outcome of small for gestational age babies born after 34 weeks of gestation: role of prenatal surveillance

Objective: Cardiac disproportion often signifies important disease
resulting in a postnatal duct-dependent circulation. Diagnostic accuracy
was prospectively assessed in fetuses referredwith disproportion
detected during routine obstetric screening (1997–2002).
Methods: We trained sonographers to recognise cardiac disproportion
in four transverse views. Fetuses without disproportion; isolated
septal defects, balanced atrioventricular septal defects, tetralogy of
Fallot or double outlet right ventricle with large pulmonary arteries,
simple transposition or moderate valvar stenosis were excluded.
Results: 293/1721 cardiac referrals were for suspected cardiac
sonographic anomalies, 109 had disproportion confirmed (60%
left sided hypoplasia). Diagnosis included isomerism (6), persistent
left superior caval vein (LSVC) (6), chromosomal defects (15),
and extracardiac malformations (25). Duct-dependent postnatal
circulation was likely in 83%.
12.8% with disproportion had no important cardiac abnormality
– 5 had aneuploidy, hydrops or vein of Galen aneurysm, 7 were
managed as suspected coarctation (CoA) (3 mild arch hypoplasia
(1 45XO), 4 normal). Continuous flow on colour and Doppler at
the isthmus (5) aided CoA diagnosis, but one with restrictive foramen
excluded it. LSVC occurred in 5.5% disproportion vs. 0.5%
referred population (p = 0.00001). Disproportion was not confirmed
in 1.5% referrals. Neonatal outcomes were confirmed in all but one
that moved abroad.
Conclusions: Recognition of cardiac disproportion is a simple but
effective protocol with a low false positive referral rate (33/1721,
1.9%) in second trimester screening.