What is Percutaneous Umbilical Blood Sampling?
Percutaneous umbilical blood sampling (PUBS), also known as cordocentesis, is a diagnostic prenatal test that involves obtaining a blood sample from the umbilical cord of a developing fetus. This procedure is utilized to assess fetal health and diagnose conditions before birth, providing vital information about fetal well-being, particularly in high-risk pregnancies.
Why is PUBS Performed?
PUBS is typically performed to detect and diagnose fetal abnormalities such as chromosomal disorders, blood conditions, infections, and certain metabolic diseases. It is also used to assess fetal anemia, particularly in cases of
Rh incompatibility between the mother and fetus. Additionally, PUBS can be employed to deliver medications or perform blood transfusions directly to the fetus.
During the PUBS procedure, an experienced healthcare provider uses
ultrasound guidance to locate the umbilical cord. A thin, hollow needle is then inserted through the mother’s abdominal wall into the umbilical cord to obtain a blood sample. The procedure is usually performed in a hospital setting and takes about 45 minutes to an hour.
While PUBS provides valuable diagnostic information, it is an invasive procedure and carries certain risks. These risks include fetal
bradycardia, preterm labor, infection, and in rare cases, fetal loss. The risk of complications is estimated to be around 1-2%. The decision to perform PUBS is typically made when the potential benefits outweigh the risks.
Who is a Candidate for PUBS?
PUBS is generally recommended for pregnant women who have abnormal results from other prenatal tests, such as
ultrasound anomalies or abnormal levels of maternal serum markers. It may also be indicated in cases of suspected fetal infection, chromosomal abnormalities, or when previous tests like
amniocentesis and
chorionic villus sampling provide inconclusive results.
How to Prepare for PUBS?
Prior to the procedure, patients may be advised to avoid eating or drinking for a few hours. The healthcare provider will explain the procedure, its benefits, and risks, and obtain informed consent. It is crucial for the patient to discuss any concerns or questions with their healthcare provider to ensure they are fully informed.
Following PUBS, patients are usually monitored for a short period to ensure there are no immediate complications, such as bleeding or contractions. It is important to report any unusual symptoms like severe abdominal pain, heavy bleeding, or fever to the healthcare provider immediately. Results from the blood tests can take a few days to a week.
What are the Alternatives to PUBS?
Alternatives to PUBS include other prenatal testing methods such as
non-invasive prenatal testing (NIPT), amniocentesis, and chorionic villus sampling. Each of these tests has its own indications, benefits, and risks. The choice of test depends on the specific clinical scenario and should be discussed with a healthcare provider.
Conclusion
Percutaneous umbilical blood sampling is a valuable tool in prenatal diagnosis, offering critical insights into fetal health. While it carries certain risks, it can provide essential information that can guide management decisions in complicated pregnancies. As with any medical procedure, informed decision-making and thorough communication with healthcare providers are key to optimizing outcomes for both mother and fetus.
