Geburtshilfe Frauenheilkd 2016; 76 - P47
DOI: 10.1055/s-0036-1583820

Prenatal ultrasound screening for morphological abnormalities in the first trimester

A Hamdi 1, A Morchdi 1, A Achour 1, C Abid 1, D Chelli 1
  • 1Center of Maternity and Neonatology of Tunis, Department A, Tunis, Tunisia


The objective of this study is to determine the different malformations accessible to prenatal screening and the contribution of early ultrasound to reduce their impact.


A retrospective study conducted in Department of Obstetrics and Gynecology „A“ in the Center of Maternity and Neonatology of Tunis. During two years: from January 2013 to December 2015.

Inclusion criteria: all patients who had a therapeutic abortion on morphological malformations detected by ultrasound in the first trimester.


We identified 17 cases of medical Interruption of pregnancy for morphological abnormalities in the first trimester ultrasound, from a total of 100 cases of medical Interruption of pregnancy, the average gestational age was 12 weeks. The average age of pregnant was 31. 8 years [19 to 43 years]. We found 7 cases of cystic hygroma (50% of malformations) and 5 brain malformations. Two case of a defect in the abdominal wall was reported.


Our study demonstrated that the first-trimester ultrasound performed at 11 – 14 weeks was able to detect 17% of major structural anomalies in chromosomally normal fetuses in singleton pregnancies. The rates of later diagnosis of these defects in the second and third trimesters, were 54% and 29%, respectively. As expected, the highest detection rates were found for acrania, holoprosencephaly, omphalocele, gastroschisis and megacystis.

Furthermore, it appears that women prefer earlier screening, when possible.

Recently, it has been described that the vast majority (83%) of omphaloceles containing only bowel and observed at 11 – 13 weeks, resolve by 20 weeks30. Moderate megacystis (7 – 15-mm bladder length) seen in normal-karyotype fetuses deserves further evaluation given that it is associated with a 90% chance of resolution and a favorable prognosis. Cystic hygroma is a well-established entity in the second trimester, but it is a confusing finding in the first trimester because the distinction between cystic hygroma and an increased NT is rather subjective.


Ultrasound in the first trimester allows the early diagnosis of major abnormalities and helps to define risk groups requiring additional investigations. Defects that need to be highlighted are: Anencephaly, holoprosencephaly, major micromelia, omphalocele, gastroschisis, coelosomy, megacystis and cystic hygroma of the neck.