title: Ultrasound measurement of placental thickness to detect pregnancies affected by homozygous alpha-thalassaemia-1.
abstract: Homozygous alpha-thalassaemia-1, a common cause of hydrops fetalis, is usually diagnosed invasively. We measured placental thickness by ultrasound at 10-21 weeks' gestation in 231 at-risk pregnancies. 60 were affected (by DNA analysis). The sensitivity and specificity in detecting affected pregnancies at cut-off of mean placental thickness plus 2 SD before 12 weeks' gestation were 0.72 (95% CI 0.52-0.93) and 0.97 (0.9-1.0). After 12 weeks sensitivity increased to 0.95 (0.89-1.0) and by 18 weeks reached 1.0 (0.60-0.99) without change in specificity. Selection of pregnancies at risk by measurement of placental thickness will reduce the number of invasive diagnostic procedures.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Hong Kong, Tsan Yuk Hospital.
authors.forename: A
authors.initials: A
authors.lastname: Ghosh
authors.forename: M H
authors.initials: MH
authors.lastname: Tang
authors.forename: Y H
authors.initials: YH
authors.lastname: Lam
authors.forename: E
authors.initials: E
authors.lastname: Fung
authors.forename: V
authors.initials: V
authors.lastname: Chan
mesh_terms: D005260:Female; D005315:Fetal Diseases / Q000000981:diagnostic imaging*; D006720:Homozygote; D006801:Humans; D007231:Infant, Newborn; D010920:Placenta / Q000000981:diagnostic imaging*; D011247:Pregnancy; D012680:Sensitivity and Specificity; D016216:Ultrasonography, Prenatal; D017085:alpha-Thalassemia / Q000000981:diagnostic imaging* / Q000235:genetics