Objective?To formulate an evidence-based conclusion concerning ultrasound screening for fetal malformations for a pregnant woman after 12 gestational weeks. Methods?Based on the clinical problem of whether pregnant women need ultrasound screening for fetal malformations after 11-14 gestational weeks, we used “ultrasound or sonography and prenatal or fetal at first trimester or 11-14 weeks; ultrasound exposure; fetal development” as the keywords and searched The Cochrane Library (Issue 4, 2008), MEDLINE (1981 to 2008), ACP Journal Club (1991 to 2008), and BMJ Clinical Evidence (1999 to 2008) for systematic reviews, randomized controlled trials (RCTs) and controlled clinical trials. The methodological quality of the included studies was assessed to identify the current best evidence. Results?Three systematic reviews, two RCTs and ten cohort studies were retrieved. The results showed ultrasound screening detected different fetal malformations in the first, second and third trimester. Not all of the fetal malformations could be detected through prenatal ultrasound screening. Nuchal translucency (NT) measurement as a tool for screening chromosomally abnormal fetuses and detecting fetal malformations by ultrasound proved to be effective if performed within 11-14 gestational weeks. The routine second trimester screening, however, could not be replaced by a detailed ultrasound examination at 11-14 gestational weeks. Most of the trials concluded that the effect of ultrasound on a fetus was not harmful. Conclusion?The findings of this study should reassure physicians and parents alike that ultrasound screening is an appropriate option for the pregnant women after 12 gestational weeks.
