Key Points The main objective of routine midtrimester ultrasonography (US) is to provide accurate diagnostic information for the delivery of optimised antenatal care, including delivery planning. Routine early US is beneficial because of better estimates of gestational age. Routine US…
Introduction Trisomies can occur with any chromosome, but most often result in spontaneous abortion. For example, trisomy 16 is the most common trisomy in human pregnancies, and the majority of the time results in miscarriage. These severe trisomies are more…
Introduction Turner syndrome (monosomy X) is characterized by complete or partial loss of the second X chromosome in the female, with or without cell line mosaicism. There are three distinct phenotypes: (1) first trimester abortus (98%), (2) second trimester hydrops…
Introduction Trisomy 21 (Down syndrome) is the most common trisomy in live-born infants and in spontaneous abortions. British physician John Langdon Down first described the syndrome in 1866. The chromosomal abnormality was discovered in 1959 by French geneticist Jerome Lejeune,…
Introduction Trisomy 18 is the second most common autosomal trisomy (after trisomy 21). Disorder Definition Trisomy 18, also called Edwards syndrome, results from the presence of an extra copy of chromosome 18. Prevalence and Epidemiology Trisomy 18 is the second…
Introduction Trisomy 13, also known as Patau syndrome, is one of the three most common trisomy syndromes. It is often diagnosed prenatally by the identification of one or more congenital abnormalities seen on ultrasound (US). Trisomy 13 is associated with…
Introduction Aneuploidy is a chromosomal anomaly in which the number of one or more chromosomes is abnormal. Normal human somatic cells (i.e., nonegg or sperm cells) carry 46 chromosomes: two copies of each of the 22 autosomal chromosomes and two…
Introduction The biophysical profile (BPP) was first described in 1980 as a method to quantify and standardize antepartum fetal evaluation. The full BPP test is performed using a combination of real-time ultrasound (US) and cardiotocography, also known as a nonstress…