Abnormalities of the Umbilical Cord

Abnormalities of the umbilical cord, related to morphology, placental insertion, number of vessels and primary tumors, can influence the perinatal outcome and may be associated with other fetal anomalies and aneuploidies. The chapter investigates the most important congenital anomalies of this structure. Single umbilical artery appears to be associated with ventricular septal defects and conotruncal anomalies, hydronephrosis, dysplastic kidneys, esophageal atresia, spina bifida, holoprosencephaly, diaphragmatic hernia, and cystic hygromas. Velamentous insertion of the cord can be associated with trisomy 21, spina bifida, ventricular septal defects, and esophageal atresia. A hypoplastic umbilical artery has an artery-to-artery diameter difference of more than 50%; described anomalies include trisomy 21, polyhydramnios, congenital heart disease, and fetal growth restriction. Pseudocysts are more common than true cysts, and they are strongly associated with chromosomal defects and other congenital anomalies, especially omphalocele, hydrops, and trisomy 18. Other benign masses are teratomas, angiomyxomas, and patent urachus. Alterations in morphology and ultrastructure of the umbilical cord should extend the investigation, since there are associations with chromosomal anomalies

The Hepatic Fetal Venous System

The vascular architecture of the human liver is established at the end of the 10th week of gestation as a result of a complex process. Recent developments in ultrasonographic imaging facilitate the prenatal evaluation of this system. However, many of the involved mechanisms are poorly understood. The hepatic primordium is in contact with the vitelline veins and the umbilical veins, and by the end of the 6th week, the afferent venous system of the liver is acquired giving rise to the portal vein, the portal sinus, and the ductus venosus. The only afferent vein of the liver that remains open at birth is the portal vein. Also, the efferent venous system of the liver is formed and emerges from the vitelline veins