EP07.59: Ultrasound detection of first trimester fetal structural abnormalities

Abstract

To describe the principles of anatomical survey during first trimester, therefore highlighting the role of first quarter ultrasonography (US) in the early diagnosis of major malformations and in the definition of high-risk groups requiring further investigations. Retrospective, longitudinal and evaluative study, carried out in Department of Obstetrics and Gynecology of the Academic Hospital of Bizerte, Tunisia over 1 year period. We have identified abnormalities likely to be observed during first trimester ultrasonographic examination. Among the 450 US carried out during the period of study, 42 abnormalities have been detected which accounts for 9.33%. Our patients' average age was 34.2. Two had history of a baby carrying the trisomy 21 gene. One patient had history of 3 therapeutic terminations of pregnancy (TTP) because of thanatophore nanism. Average echographic term was of 12 weeks + 6 days. Average nuchal translucency (NT) in MOM was 2,16 (0,41-6,67 MOM). 36 NTs were higher than 2,5 MOM which represent 85,7% of overall measured NTs. Nasal bones absence was detected in 5 fetuses (11,9%). 42 abnormalities have been detected. The most frequent ones were pathologies of soft tissues (73.8%) with 29 increased NTs and 2 cases of cystic hygroma. We listed: 1 case of choroid plexus cyst, 1 of exencephaly, 1 of megacystis, 2 of omphalocele, 1 of gastroschisis and 1 of triploidy. 6 cases of limbs abnormalities were also diagnosed. 37 patients (88.1%) were subject to fetal takings. Fetal karyotype was normal in 31% of the cases. A TTP was carried out in other cases where karyotype confirmed aneuploidy's existence. Examination of the fetus confirmed the prenatal diagnosis. Today, first trimester ultrasonographic examination allows diagnosis of severe pathologies and an earlier management. However, some pathologies are not detectable at such an early stage and some others can be suspected but precise diagnosis and prognostic evaluation can only be confirmed later.