This technique has been used to treat fetal anaemia caused largely by Rhesus incompatability over the last three decades but has become increasingly common and relatively safe since the development of high resolution ultrasound particularly with colour Doppler capability.
All the genetic information is present in every cell in the body, stored by DNA, which is found in the chromosomes. There are 23 pairs of chromosomes, the last pair being XX for female and XY for male. Fetal cells obtained by amniocentesis, CVS or fetal blood sampling can be analysed giving a picture of the chromosomes.
"FISH" can analyse the most common chromosomes involved in genetic defects.
The fetal circulation is usually accessed through the placental cord insertion although a free loop or fetal cord insertion can also be used. It is also possible to use the intrahepatic portion of the umbilical vein in certain situations.
The risk of these procedures is now largely dependent on the prior condition of the fetus and the gestational age at which transfusion is commenced.