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| Fetus week 9-10 (Photo credit: lunar caustic) |
Besides amniocentesis and chorionic villus sampling, there is another advanced method for paternity DNA testing. This is the percutaneous umbilical blood sampling or also known as cordocentesis. It is performed during the second trimester or 18th week of pregnancy.
The procedure entails the use of advanced imaging ultrasound to determine the location where the umbilical cord inserts into the placenta. In the process, a thin needle is inserted through the abdomen and uterine walls to the umbilical cord. The ultrasound serves as guide to the process of insertion. Then, the needle is inserted into the umbilical cord to get a small sample of fetal blood.
This method is performed in the hospital while the sample is sent to the laboratory for analysis. Often, the results are released within 72 hours or three working days.
The percutaneous umbilical cord blood sampling’s procedure is similar with amniocentesis. Only, the goal in this process is to retrieve fetal blood and not amniotic fluid. This procedure also provides a rapid chromosome analysis within high levels of accuracy. Yet, it cannot measure the severity of these disorders even if it can accurately identify them.
There are times that this procedure is useful when results cannot be obtained through amniocentesis, chorionic villus sampling, or ultrasound. The percutaneous umbilical cord blood sampling detects chromosome abnormalities such as Down syndrome and blood disorders such as fetal haemolytic disease. This procedure can also diagnose disorders such as malformations of fetus, fetal infection such as toxoplasmosis or rubella, fetal platelet count in the mother, fetal anaemia, and isoimmunisation to name a few. However, this procedure is not performed for neural tube defects.
It should be noted that the procedure has a high risk of complication. That is why it is typically performed during special cases particularly with pregnancies determined to be at high risk for genetic disorders.
In addition, the percutaneous umbilical cord blood sampling provides pregnant women with several opportunities. These include pursuance of potential medical interventions that may exist, early start to plan for a child with special needs, early start to address anticipated lifestyle changes, search for a support groups or resources, and making a decision about carrying the child to term.
Some couples and pregnant women though, choose not to undergo such procedure for several reasons. For instance, they are not comfortable with the results. Sometimes, their reasons are based on personal, moral, and religious grounds.
Like any other procedure, it is also important to take note of the risks of the procedure. This is very important with percutaneous umbilical blood sampling for it is considered as high-risk process—it being an invasive diagnostic test.
This procedure poses high chances of miscarriage with a rate of one to two times out of every 100 procedures. Other potential adverse effects include blood loss from the puncture site, infection, drop in fetal heart rate, and premature rupture of membranes. Signs of possible side effects may include fever, chills, discomfort similar to menstrual cramp, and leaking of amniotic fluid.
