Umbilical cord is used in place of a bone marrow transplant in the treatment of blood disorders such as leukemia, with donations released for transplant through one registry, Netcord.org, passing 1,000,000 as of January 2013. Cord blood is used when the patient cannot find a matching bone marrow donor; this "extension" of the donor pool has driven the expansion of public banks. The umbilical cord in some mammals, including cows and sheep, contains two distinct umbilical veins. There is only one umbilical vein in the human umbilical cord. In some animals, the mother will gnaw through the cord, thus separating the placenta
Percutaneous umbilical cord blood sampling preexisting defects and abnormalities. While ultrasounds and color flow mapping can be used to avoid the umbilical artery and sample from the umbilical vein, the dilation makes the single umbilical artery easier to puncture. Blood flow in the umbilical artery is seen to be twice the normal amount from about 20 weeks on so the effects of a punctured umbilical artery during PUBS are more severe. Percutaneous umbilical cord blood sampling "For other uses see PUBS ( page)" Percutaneous umbilical cord blood sampling (PUBS), also called cordocentesis, fetal blood sampling, or umbilical vein sampling is a diagnostic genetic test that