Screening for nuchal translucency

Measurements give parents useful information

Editorial by McFadyen et al

EDITOR—I would like to address two issues raised by Venn-Treloar in her comments about screening for nuchal translucency without the consent of the mother.1 Firstly, it is incontrovertible that mothers attending for ultrasound scanning in the first trimester believe that the test is designed to confirm that the baby is well. However, I would argue that an inspection for fetal anomalies, including measurement of nuchal translucency, generates such a diagnosis. Secondly, I disagree that the key purpose of measuring nuchal translucency is to decrease the birth rate of children with Down's syndrome.

Patients presenting for ultrasound scanning expect the operator to perform a detailed examination to confirm fetal health. In the majority of cases the fetus is normal but unfortunately in about 2% of cases an abnormality is seen. The benefit of early diagnosis of fetal anomalies is that information can be provided to enable couples to consider various options and to allow appropriate plans to be made for treatment and follow up.

Outcome depends on the recognition of the potential severity of defects; these defects fall into four groups. In lethal conditions, such as anencephaly, the couple may wish to consider the options of terminating or continuing the pregnancy. In disorders that are not lethal but are associated with death, such as diaphragmatic hernia, planned delivery in a centre with appropriate neonatal intensive care facilities will optimise neonatal outcome. In abnormalities that are associated with childhood morbidity such as hydronephrosis, and which may lead to renal failure due to urinary tract infections, prenatal diagnosis provides the opportunity for early postnatal treatment. In the case of chromosomally abnormal fetuses where there is a risk of physical and mental handicap, the couple may wish to continue the pregnancy or undergo …