Routine obstetrical ultrasound at 18-22 weeks: our experience on 7,236 fetuses

This study aimed at examining the detection rate of congenital abnormalities by using routine ultrasonography at 18-22 weeks of gestation.

The sample included 7,236 fetuses. A detailed sonographic examination was performed in each fetus and a neonatal evaluation or pathology examination was made to confirm the prenatal findings.

The total prevalence of fetal abnormalities in our sample was 2.24% (162/7,236). There were 29/162 (17.9%) fetuses with CNS abnormalities, 27/162 (16.7%) fetuses with gastrointestinal abnormalities, and 28/162 (17.3%) fetuses with urinary tract abnormalities. There were also 31/162 (19.1%) fetuses with cardiovascular abnormalities, 26/162 (16.0%) with malformation of the limbs and musculoskeletal system, and 21/162 (13%) fetuses with other various abnormalities. The overall sensitivity in detecting fetuses with congenital abnormalities was 80.25% (130/162). The sensitivity per system was 93.1% (27/29) for CNS, 45.2% (14/31) for cardiovascular system, 85.2% (23/27) for gastrointestinal system, 85.7% (24/28) for urinary system, 84.6% (22/26) for musculoskeletal system, and 95.2% (20/21) for the rest of the abnormalities detected. We performed 40 pregnancy terminations in the group of malformed fetuses. Among the fetuses considered as normal, 1.7% had chromosomal abnormalities.

The results indicate that routine sonographic examination at 18-22 weeks of gestation can detect the majority of congenital abnormalities. More experience is needed for the examination of the cardiovascular system, where the sensitivity was particularly low (14/31 or 45.2%).