Fetal 'space-suit' hydrops in the first trimester: differentiating risk for chromosome abnormalities by delineating characteristics of nuchal translucency.

Detecting first trimester fetuses with pan-body hydrops, giving the appearance of a 'space-suit,' is associated with a marked increased risk for chromosome abnormalities. In 30 consecutive fetuses prospectively characterized by space-suit hydrops, detected at or before 13.9 weeks' gestation, 26 (86.7%) were characterized by chromosome abnormalities. However, as opposed to the preponderance of autosome abnormalities among first-trimester fetuses with prominent nuchal translucencies, 15 of the 26 fetuses (57.7%) with abnormal complements were characterized by sex chromosome aneuploidies. Genetic counselling and consideration of invasive prenatal testing is warranted when space-suit hydrops is detected in the first trimester.