Fetal structural anomalies diagnosed during the first, second and third trimesters of pregnancy using ultrasonography: a retrospective cohort study

ABSTRACT BACKGROUND: The prevalence of congenital abnormalities in general populations is approximately 3-5%. One of the most important applications of obstetric ultrasound is in detection of fetal structural defects. OBJECTIVE: To assess fetal structural anomalies diagnosed using ultrasound in the three trimesters of pregnancy. DESIGN AND SETTING: Retrospective cohort study at the Mário Palmério University Hospital of the University of Uberaba (Universidade de Uberaba, UNIUBE), from March 2014 to December 2016. METHODS: Ultrasound data at gestational weeks 11-13 + 6, 20-24 and 32-36 were recorded to identify fetal anomalies in each trimester and in the postnatal period. The primary outcome measurements were sensitivity, specificity, positive predictive value and negative predictive value for detection of fetal anomalies and their prevalence. RESULTS: The prevalence of anomalies detected using ultrasound was 2.95% in the prenatal period and 7.24% in the postnatal period. The fetal anomalies most frequently diagnosed using ultrasound in the three trimesters were genitourinary tract anomalies, with a prevalence of 27.8%. Cardiac anomalies were diagnosed more often in the postnatal period, accounting for 51.0% of all cases. High specificity, negative predictive value and accuracy of ultrasound were observed in all three trimesters of pregnancy. CONCLUSION: Ultrasound is safe and has utility for detecting fetal anomalies that are associated with high rates of morbidity and mortality. However, the low sensitivity of ultrasound for detecting fetal anomalies in unselected populations limits its utility for providing reassurance to examiners and to pregnant women with normal results.

【研究背景】普通人群中先天性异常的患病率约为3%~5%。产科超声（obstetric ultrasound）最重要的应用之一便是检测胎儿结构畸形。
【研究目的】评估妊娠三个孕期通过超声（ultrasound）诊断的胎儿结构异常情况。
【研究设计与研究场所】本研究为回顾性队列研究，于2014年3月至2016年12月期间在乌贝拉尔巴大学（Universidade de Uberaba, UNIUBE）的马里奥·帕尔梅里奥大学医院开展。
【研究方法】收集妊娠周数11~13⁺⁶周、20~24周及32~36周的超声数据，以识别各孕期及产后阶段的胎儿异常。本研究的主要结局指标为胎儿异常检测的灵敏度、特异度、阳性预测值、阴性预测值以及异常患病率。
【研究结果】超声检出的胎儿异常在产前阶段的患病率为2.95%，产后阶段为7.24%。三个孕期通过超声最常检出的胎儿异常为泌尿生殖道异常，患病率达27.8%。心脏异常则更多在产后阶段被确诊，占所有病例的51.0%。在妊娠的三个孕期中，超声均表现出较高的特异度、阴性预测值及诊断准确度。
【研究结论】超声安全可靠，可有效检出与高发病率和高死亡率相关的胎儿异常。但在未经过筛选的人群中，超声检测胎儿异常的灵敏度较低，这限制了其为检查医师及结果正常的孕妇提供安心保障的应用价值。