What is cordocentesis (percutaneous umbilical blood sampling)?

Cordocentesis (Percutaneous Umbilical Blood Sampling)

Cordocentesis is a prenatal diagnostic procedure that involves ultrasound-guided needle insertion into the umbilical cord vessels (usually the vein) to obtain fetal blood samples for diagnostic or therapeutic purposes. 1

Procedure Overview

Cordocentesis, also known as percutaneous umbilical blood sampling (PUBS) or funipuncture, is a specialized procedure that provides direct access to fetal circulation during pregnancy. The procedure involves:

• Ultrasound guidance to visualize the umbilical cord
• Insertion of a needle into an umbilical vessel (typically the vein)
• Collection of fetal blood specimens for testing or administration of treatment

Timing and Technical Approach

• Typically performed between 17 and 40 weeks of gestation 1
• Three main approaches to access the umbilical cord:
  • Direct puncture
  • Indirect puncture
  • Free puncture
• An anteriorly placed placenta allows for easier access to the umbilical cord
• The procedure typically takes approximately 4 minutes to complete
• Number of puncture attempts should be limited to a maximum of 3 to reduce complications 1

Primary Indications

Diagnostic Applications

• Suspected fetal anemia (most common indication) 1
• Diagnosis of congenital infections
• Cytogenetic analysis (karyotyping)
• Evaluation of metabolic disorders
• Assessment in fetal growth restriction
• Diagnosis of hematologic disorders
• Direct assessment of fetal thyroid function 1

Therapeutic Applications

• In utero blood transfusions for rhesus alloimmunization
• Administration of medications directly to the fetus 1

Complications and Safety Considerations

• Literature demonstrates a relatively low incidence of complications 1

• Potential risks include:

  • Bleeding from the puncture site
  • Fetal bradycardia
  • Vertical transmission of maternal infection
  • Placental abruption (particularly with anterior placenta)

• The risk of complications increases with:

  • Longer procedure duration
  • Higher number of puncture attempts
  • Procedures performed for therapeutic rather than diagnostic purposes 1
  • Severity of the underlying fetal condition 1

Clinical Outcomes

Neonates who undergo PUBS may experience a higher occurrence of complications compared to gestational age-matched controls, including:

• Increased respiratory complications despite higher rates of antenatal corticosteroid administration 2
• These complications appear to be independent of prematurity alone 2

Best Practices

• Should be performed at specialized perinatal care centers
• Only highly trained and experienced physicians should conduct the procedure 1
• Careful selection of cases is essential as the risk of complications is directly related to the severity of the underlying condition
• The benefits of obtaining diagnostic information or providing therapy must be weighed against the procedural risks

Cordocentesis represents an important tool in fetal medicine that has expanded the possibilities for prenatal diagnosis and therapy by providing direct access to fetal circulation.