Down syndrome screening: About 33 cases

Background: Trisomy 21 is responsible of different anatomical malformations and more or less severe mental retardation. Prenatal screening has grown in recent years. Tunisian studies on prenatal screening for Trisomy 21 are few. There are yet no screening strategies well codified at prenatal care units. The aim of our study was to Specify the various strategies for prenatal screening for Trisomy 21 and evaluate the results.

Methods:

Our retrospective study was conducted at the service "A" of the center of Maternity and of Neonatology of Tunis during a period of 10 years. We included all cases of Trisomy 21 diagnosed prenatally, born alive or abortion products. We searched screening methods used and we evaluated their performance.

Results:

In our study, the overall prevalence of Trisomy 21 was 1.67 ‰ pregnancies. Prenatal screening interested 46.47% of patients. The diagnosis of Trisomy 21 was prenatally made in 84.84% of cases. 15.15% of the patients escaped prenatal diagnosis. The mean maternal age was 36.14 years. The mean gestational age at diagnosis was 17 weeks. Ultrasound screening led to the diagnosis in 54.54% of cases with a sensitivity of 61.11%. Maternal serum markers (free fraction β hCG and PAPP-A) contributed to the diagnosis in 9.09% of cases with positive income in all cases. Those of the 2nd trimester (free fraction β hCG, AFP, unconjugated estriol) were achieved in 24.24% of cases, with a sensitivity of 75%. Second trimester ultrasound scan has detected 33% of fetuses with T21.

Conclusion:

Prenatal screening for Trisomy 21 is constantly improving. Ultrasound screening (especially that of the first trimester) is an important pillar in screening strategies. This fact encourages us to improve its quality by training professionals involved. We also should ensure the availability of biomarkers for all women.