PERFORMANCE OF PRENATAL ULTRASOUND ON DIAGNOSIS OF FETAL CHROMOSOMAL ABNORMALITIES IN A TERCIARY CENTER

Abstract
Objective: to estimate the performance of ultrasound to detect gestations at risk for fetal chromosomal abnormalities.Patients and Methods: 436 patients were selected for the study had undergone ultrasound examination and fetal karyotyping, between March 1993 and March 1998. 277 patients had fetal malformation detected on ultrasound and 158 for parental anxiety with normal ultrasound examination. Ultrasound accuracy were calculated using fetal karyotype as gold standard. The relative risk was calculated for each fetal organic system and for the presence of isolate or associated abnormalities on ultrasound, using the software package EPINFO 6.0 for statistical analysis.Results: The relative risks for chromosomal abnormalities were 89,04 for face malformations, 53,00 for abdominal wall and cardiovascular, 49,69 for neck, 44,69 for extremities, 42,40 for lung, 32,74 for gastrointestinal tract, 27,41 for central nervous system and 23,08 for urinary tract malformations. The relative risk for genitals, thorax, spine and muscle and/or skeletal malformations was not appropriated for calculation because their low frequency. An isolated malformation detected by ultrasound had relative risk for of 7,82 times higher than none, and associated morphologic malformations had a relative risk of 33,85.Conclusion: Ultrasound has good performance to detect gestations at risk for chromosomal abnormalities.

Key words
Ultra-som, cromossomopatias fetais, diagnóstico pré-natal, cariótipo

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