First-trimester combined screening for trisomy 21 in women at risk for α-thalassemia

Abstract

Objective: To report the strategy of first-trimester aneuploidy screening in pregnancies at risk for homozygous α⁰-thalassemian.

Methods: Women at risk of homozygous α⁰-thalassemia were given an ultrasound examination at 11–14 weeks’ gestation to exclude an affected pregnancy. Fetal cardiothoracic ratio (CTR) and nuchal translucence (NT) were measured. If cardiomegaly was found, chorionic villus sampling (CVS) was offered for α-thalassemia; otherwise the first-trimester combined screening test was performed on the pregnancy. The invasive testing for karyotyping was only followed in those cases with a positive aneuploidy screening test.

Results: In total, 69 of 288 pregnancies were found to be affected by homozygous α⁰-thalassemia using ultrasound, and the findings were confirmed by invasive testing. In the remaining 219 pregnancies, invasive testing was not performed for α-thalassemia because of a normal fetal CTR, and the women received the first-trimester combined screening. Nine CVS procedures were performed for karyotyping because of a positive aneuploidy screening. Totally three pregnancies with aneuploidy were diagnosed and terminated.

Conclusions: Our strategy can selectively detect aneuploidy pregnancies not affected by homozygous α-thalassemia, and, meanwhile, save on the cost of unnecessary aneuploidy screening or karyotyping in pregnancies with an affected fetus of homozygous α⁰-thalassemia.

• α⁰-thalassemia
• aneuploidy
• cardiomegaly
• prenatal screening
• prenatal ultrasonography

Declaration of interest

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.