Is ultrasound alone enough for prenatal screening of trisomy 18? A single centre experience in 69 cases over 10 years

Abstract

Ultrasound scan for fetal anomalies is the most effective screening test for trisomy 18. A policy of conservative management for women with positive second-trimester biochemical screening or first-trimester combined screening for trisomy 18 is reasonable in the absence of ultrasound fetal abnormalities. Unnecessary invasive tests can be avoided.

Prenatal diagnosis of trisomy 18: Report of 76 cases in a mainland Chinese hospital

“…Ultrasound scan for fetal anomalies is the most effective screening test [2][3][4]. As also shown in the current study, almost all of the affected pregnancies were referred for the indication of abnormal ultrasound findings.…”

Trisomies 18 and 13: trends in prevalence and prenatal diagnosis – population based study

“…In the UK, screening for T18 and T13 is undertaken as part of the routine second trimester foetal anomaly scan at 18 +0 –20 +6 weeks. Cases may be suspected in the first trimester by routine ultrasound for dating, or by incorporating risk calculation for T18/T13 into the first trimester combined test . The extension of the first trimester combined test to include screening for other aneuploidy is currently not supported within the UK programme, although a consultation on this is currently underway.…”

Prenatal diagnosis of i(18q) and dup(18q) cases by quantitative fluorescent PCR

“…The detection rate of the US scan at 18–21 weeks to detect trisomy 18 in a series of 69 women was 100%, and 92.7% in 14 or less weeks of pregnancy. A total of 80% and 87% of fetuses had two or more US abnormalities detected in the ≤14 and 18–21 weeks anomaly scans, respectively 7. Many other reports support the conclusion that in experienced hands, the sensitivity of detecting fetal trisomy 18 on prenatal sonography is 100%, and all cases will have multiple anomalies visualised 8–15…”