Division of Clinical Research, Climax Radiology Education Foundation, Tehran, Iran Division of Clinical Research, Iranian Association of Fetal Ultrasound, Tehran, Iran
Currently, a fetus with thick nuchal translucency (NT) on ultrasound screening is referred for genetic counselling and invasive diagnostic testing, because an increased NT thickness is strongly associated with aneuploidies particularly trisomy 21. However, presence of thick NT with normal karyotyping is not uncommon and causes a major challenge both for the clinician and the parents. There is a wide spectrum of conditions that may lead to a thick NT with normal karyotype such as genetic syndromes and congenital heart defects. Also, it can be associated with an increased risk of intrauterine fetal demise. In this lecture, current knowledge related to this topic and a stepwise approach in case of thick NT detection on sonography would be presented.