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KMID : 0616620030090020197
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Journal of Soonchunhyang Medical College
2003 Volume.9 No. 2 p.197 ~ p.205
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Comparison of first and second trimester screening for fetal anomalies
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Choi Seung-Do
Lee Jeong-Jae
Choi Gyu-Yeon
Lee Im-Soon
Jeong Seong-Yun
Lee Kwon-Hae
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Abstract
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Objective: Ultrasonographic screening between 9 and 13 weeks for fetal structural abnormalities using transvaginal sonography in unselected population. Visualization of detailed fetal anatomy in the first trimester has improved as a result of technological progress in ultrasound machines and the introduction of transvaginal sonography(TVS). Our study aims to evaluate the accuracy of TVS as a screening tool for detecting fetal malformations in a nonselected population of pregnant women. For this purpose we compared the results obtained by using second trimesster TA scanning with those obtained using TVS at 9-14 weeks’ gestation.
Methods: From March 2001 to February 2003, 620 unselected consecutive pregnant women were recruited at their initial visit at Soonchunhyang university hospital, department of obstetrics and gynecology and offered a TVS scan at the average gestational age of 9-13 weeks in addition to the TA screening usually performed between 22-26 weeks. To fulfill the technical requirements of a screening test, ultrasonographic examinations were performed by skillful operators with different degrees of experienced using adequate instruments Aloka SSD 5500 (Aloka Co. Ltd., Tokyo, Japan) provided with either a 3.5-5MHz TA probe or a 5-7.5MHZ TV probe) in a fixed scanning time of maximum 30 min, generally considered sufficient for a complete fetal anatomic survey.
Results: During the study period we found in our unselected population an overall prevalence of target abnormalities of 2.2%(24 malformed fetuses out of 600 screened). In the fetuses examined by TVS, 16 abnormalities were detected whereas 8 were not; of these, 6 were detected at transabdominal rescreening at 22-26 weeks and the remaining 2 were observed after birth. A nuchal region abnormality was the most frequent type of malformation detected in the early scan, including six cases of nuchal edema, two cases of cystic hygroma associated with hygroma associated with hydrops, three cases of hydronephrosis, one case of fetal neck teratoma, one case of cleft lip.
Conclusion: This study has demonstrated the potential of screening a low risk population for fetal abnormalities at 9-13 weeks of gestation using transvaginal sonography and rescreened via transabdominal sonography at 22-26 weeks. Larger studies are required to establish the clinical value of the first trimester scan.
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KEYWORD
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fetal anomaly, first trimester, second trimester, ultrasonography
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