Important Tests during pregnancy help check the baby's growth and health, as well as the mother's well-being.
Percutaneous umbilical blood sampling (PUBS) or cordocentesis, is a diagnostic process used to elevate many different kinds of fetal conditions. PUBS is usually conducted after 18 to 19 weeks of pregnancy. During this process, a trained specialist uses ultrasound to guide a needle through the maternal abdomen and into the umbilical cord where the sample of fetal blood can be taken.
After the process, the blood sample can be used to diagnose a wide spectrum of fetal conditions, ranging from infections to genetic disorders.
- What is Percutaneous Umbilical Blood Sampling?
- Purpose of Percutaneous Umbilical Blood Sampling (PUBS)
- Risks of PUBS
- Guidelines to Follow Before the PUBS Test
- Detailed Process of Prenatal Percutaneous Umbilical Blood Sampling Test
- After the PUBS Test
- Interpreting PUBS Test Results
What is Percutaneous Umbilical Blood Sampling?
Percutaneous umbilical blood sampling is also called as cordocentesis. It is a diagnostic process used to evaluate many different kinds of fetal conditions.
PUBS is usually conducted after 19 to 19 weeks of pregnancy. During this process, a trained specialist uses ultrasound imaging to guide a needle through the maternal abdomen and into the umbilical cord where the sample of fetal blood can be taken.
After the process, the blood sample can be used to diagnose a wide spectrum of fetal conditions, ranging from infections to genetic disorders.
Also Check: Glucose Screening Tests in Pregnancy
Purpose of Percutaneous Umbilical Blood Sampling (PUBS)
PUBS is used only when less invasive diagnostic procedures cannot provide conclusive results. In most cases, PUBS is used to diagnose blood conditions of a fetus such as anemia, through fetal infections and certain genetic conditions can also be diagnosed with a PUBS procedure.
PUBS test is used to diagnose:
- Genetic or chromosomal abnormalities
- Fetal anaemia and other blood disorders such as Rh disorders, thrombocytopenia
- Fetal oxygen levels
- Fetal infections (toxoplasmosis, nonimmune hydrops)
PUBS is also used to administer medications to the fetus and perform blood transfusions. Based on the concern, PUBS may be used to help treat a disease or disorder of the fetus before the baby is born.
Another application of PUBS is stem-cell transfusion. This has been used to treat patients with conditions such as severe combined immunodeficiency (SCID) and beta-thalassemia.
Risks of PUBS
In most cases, the advantages of performing this test outweigh risks, but discuss with your healthcare provider if you have concerns.
PUBS is performed around 18 weeks of pregnancy or gestation can be performed later in the pregnancy. The most common risks and complications include the following:
In almost 30% of cases, the process can lead to bleeding at the site of the needle insertion into the umbilical cord. A blood transfusion may be ordered if there is significant fetal blood loss.
In some cases, a cord hematoma, a blood collection in the umbilical cord can occur. This is not a concern and can be monitored most of the time. If it causes the fetal heart rate to slow and it does not recover, an emergency c-section may be necessary.
Fetal-maternal bleeding can also occur. This is when fetal blood enters the pregnant person's circulatory system. It is typically a small amount and does not cause any problems.
The process itself can lead to infection in the patient or in the fetus. The risk of happening infection is low if your healthcare provider uses proper sterilized items and techniques, before, during and after the procedure.
It is typically temporary for the fetal heart rate to slow and generally resolves within 5 minutes. Your healthcare provider will monitor you and the fetus after the process to ensure you recover well.
As with other invasive forms of prenatal testing, there is a high risk of pregnancy loss during this process. The rate of pregnancy loss for the PUBS procedure is about 1.3% and 1.9%. However, many people take this test when they know there is a serious problem, so it is difficult to determine if the rate is this high due to the procedure itself or if the pregnancy loss would have occurred anyway due to a disease or disorder.
Guidelines to Follow Before the PUBS Test
It would help if you communicated with your healthcare provider before the test so that you can understand the risks and benefits. They will also share information about the test to help reduce your anxiety.
The actual PUBS test does not take much time. You may expect to spend a few hours at the office or hospital for paperwork, preparation and recovery.
Sometimes the test will be performed in the healthcare provider's office or at an outpatient facility. In some cases, it may be done in the hospital so that the patient can be monitored after the procedure.
Wear comfortable clothes to your hospital appointment. Your healthcare provider will ask you to change into a hospital gown for easy access to the abdomen.
Your healthcare provider may tell you not to eat or drink after midnight the night before the procedure in case emergency surgery is needed.
This process is covered by most insurance plans since it is usually performed when medically needed. Your out of pocket cost will depend on your insurance coverage, deductible, and so on.
Things to Carry to the PUBS Test
Although the PUBS test is often performed in a medical hospital and generally only takes a few minutes, it may be best to bring an extra set of clothes and supplies to stay in the hospital overnight.
As the test is typically only performed when the healthcare provider is not sure about a problem regarding fetal development, there may be a need for further intervention, testing, or surgery that was not originally anticipated. You should bring a spouse or an attendee to the appointment with you for emotional and physical support if needed.
Detailed Process of Prenatal Percutaneous Umbilical Blood Sampling Test
At least 30 to 60 minutes before going for the actual test, you may be given an IV antibiotic to reduce the risk of infection. Your healthcare provider and an assistant will use an ultrasound to look at the fetal position and the placenta.
Once the healthcare provider finds where they have to insert the needle, they will clean the skin using an antiseptic and insert the hollow needle into the abdomen. If the placenta is attached to the front of the uterus, the needle will not need to pass through the amniotic fluid.
If the placenta is attached to the back of the uterus, the needle will pass through the amniotic fluid before being inserted into the vein in the umbilical cord. Your healthcare provider will withdraw blood for testing. If no further treatment such as medication or blood administration is needed, the needle will be withdrawn and the process is complete.
After the test, your healthcare provider should monitor the injection site immediately for bleeding. They may want to monitor you for a few hours. Occasionally the fetal heart rate will drop after the PUBS process and it will be necessary to continue monitoring to ensure it returns to normal.
After the PUBS Test
You should expect test results within a few weeks. Once you return home, watch for signs of infection such as:
- Fever
- Redness or swelling around the place where the needle was inserted
- Chills
- Lethargy or feeling sick
- Other signs to watch and call your healthcare provider are as follows:
- Bleeding from the insertion site
- Early rupture of membranes (water breakage too soon)
- Leakage of amniotic fluid
- Vaginal bleeding
Interpreting PUBS Test Results
Because the PUBS process is used to diagnose conditions that are often life-threatening to the fetus, waiting for and getting the results can be a time of high anxiety and worry. If your healthcare provider is concerned about a particular diagnosis, it may help to research the diagnosis before the test and while you wait for the results.
However, it is important to get your information from reputable sources. There is a lot of misinformation available and it can cause even greater stress and worry. Ask your healthcare provider that provide you with accurate information.
Make a list of questions for your healthcare provider before getting the results so that you make sure you get the information you need. If you receive a particularly difficult diagnosis that shows your baby will have disabilities or likely not survive, take time to grieve, talk with family and friends, and make an informed decision about how best to handle the situation.
Conclusion
PUBS is not used to diagnose fetal abnormalities as often as other tests such as amniocentesis and CVS, but it is still used in some cases. It can be beneficial in treating blood disorders and fetal hydrops. It is not used to diagnose chromosomal abnormalities due to the availability of testing that poses fewer risks.
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