Turner syndrome is normally picked up during early childhood or puberty but can also now be discovered in an amniocentesis. During pregnancy the ultrasound may pick up heart or kidney abnormalities or occasionally swelling of the body tissues. Also the swelling may be present and picked up on at birth which causes further investigation.
The next time that it may be suspected is early childhood through either symptoms like short stature, webbed neck etc may be noticeable or when slow growth is noticed during childhood.
Finally suspicions may be raised when puberty doesn’t come or periods aren’t commencing.
Once any suspicions are raised then testing can begin either during amniocentesis which is a sample of amniotic fluid sent for a Karyoptype (analysis of cells/chromosomes) or once born a sample of blood for analysis of chromosomes.