Prenatal Diagnosis and Consequences. Prenatal diagnosis of discordant umbilical arteries is possible with ultrasound. Different umbilical artery flow waveforms may result in discordancy of umbilical arteries. Discordancy of size between the umbilical arteries is considered to be an incomplete form of the single umbilical artery syndrome, caused by abnormal placentation or insertion of the umbilical cord. To rule out fetal malformation detailed ultrasound examinations and fetal surveillance are mandatory.