Routine screening for fetal limb abnormalities in the first trimester

Abstract

OBJECTIVE: We aim to determine the accuracy of first-trimester ultrasonography in detecting fetal limb abnormalities. METHODS: This is a retrospective study of all women undergoing fetal nuchal translucency (NT) assessment and detailed fetal anatomic survey in the first trimester at a single tertiary-care referral center in China. Fetal anatomy scans were repeated in the second trimester. Detection of fetal limb abnormalities was compared between first and second trimester anatomy scans and confirmed at delivery or at autopsy. RESULTS: Analyzed were 9438 fetuses from 9197 women (241 twin pairs). The incidence of fetal limb abnormalities was 0.38% (36/9438). Of these, 28 (77.8%) were diagnosed prenatally: 23 (63.9%) on first trimester scan and 5 (13.9%) on second trimester scan. Limb reduction defects (usually transverse limb deficiencies) were the most common limb defects identified in the first trimester (n = 12), followed by clubfoot (n = 4), skeletal dysplasia (n = 3), sirenomelia (n = 1), limb dysplasia (n = 1), malposition (n = 1), and syndactyly (n = 1). Nine fetuses with isolated limb abnormalities had normal NT, while 74.1% (20/27) of limb abnormalities that were associated with other abnormalities had increased NT. CONCLUSIONS: This study demonstrates that the majority of limb abnormalities detected prenatally [23/28 (82%)] can be identified in the first trimester, especially major limb defects; however, our numbers are small and still need larger cases for further investigation.