For decades, postnatal cord blood has been used for blood gases, blood typing and antibody testing of newborns. So, why can’t it be used for other tests?
This question was first studied in 1981. Researchers looked at whether umbilical cord blood could be used to detect neonatal bacteremia. They found that meticulously collected cord blood was as good a source for blood culture as blood from any site (Polin JI, et al. Obstet Gynecol. 1981;57:233-237).
More recently, studies have shown that cord blood can be used for many other laboratory studies after birth. Postnatal cord blood sampling (PCBS) can be performed for all neonatal intensive care unit admissions, early-onset sepsis evaluations, initial and follow-up genetic testing, and studies for infants with congenital anomalies and deaths that occur prior to or after delivery.
A new AAP clinical report describes the evidence for and benefits of collecting cord blood after delivery as well as the laboratory studies that can be obtained. The report, from the Committee on Fetus and Newborn, also includes figures and tables with photos and graphics that outline key steps for performing PCBS.
The clinical report Postnatal Cord Blood Sampling is available at https://doi.org/10.1542/peds.2025-071811 and will be published in the June issue of Pediatrics.
Benefits of PCBS
PCBS is a painless and simple procedure that can be used for any infant of any gestational age. It should be the first choice when the need for phlebotomy is known at or shortly after delivery.
PCBS can be used for complete blood cell counts, blood cultures, blood typing and crossmatching, newborn screening and metabolic tests, genetic testing, blood chemistries and coagulation studies. It can help obtain better volumes for blood cultures than other sites, improving their yield. Similarly, for blood typing and crossmatch as well as when genetic testing is indicated, PCBS can obtain these larger volume studies more easily without infant blood loss.
Depending on what laboratory studies are needed, the benefits can be substantial, especially for newborns whose birth weight is less than 1,500 grams. Admission blood test volume for very low birth weight (VLBW) infants may be as high as 10% of their blood volume, which may contribute to hypotension.
One of the key studies found that on average, 7.5 mL/kg of phlebotomy blood loss occurs in the first 24 hours after birth for VLBW infants (Baer VL, et al. J Perinatol. 2013;33:363-365). In conjunction with delayed cord clamping (DCC), PCBS is associated with less vasopressors use, higher hemoglobin concentrations and fewer erythrocyte transfusions in VLBW infants.
Richard A. Polin, M.D., FAAP, one of the first to study PCBS for blood cultures, points out that blood cultures are most likely to identify a pathogen when infants have signs and symptoms of infection. If that is at or shortly after delivery, PCBS is a great source. If new signs and symptoms occur later, obtaining a blood culture from the infant at that time would be indicated.
Instituting PCBS
The report outlines what clinicians need to implement PCBS:
- A dedicated team (or provider) that facilitates successful rates of blood collection, sterility for blood cultures and quality of all blood samples.
- A procedural guideline.
- A process to discuss before and after every delivery if any blood tests can be obtained by PCBS.
- A kit, cart or box with supplies organized, stocked and easily available for deliveries.
- Appropriate antisepsis of the phlebotomy site to ensure a “meticulous and fastidious” blood culture collection, similar to any blood culture collection procedure.
- Childbirth personnel who can ensure that the cord remains clamped (or replaced by a disposable clamp) after delivery and delayed cord clamping (or cord milking).
Summary points
- PCBS is a painless, simple procedure to obtain infant blood.
- PCBS should be the first choice for any infant needing phlebotomy at or shortly after delivery.
- Blood obtained through PCBS is commonly used for admission studies, early-onset sepsis evaluations and genetic testing.
- In VLBW infants, PCBS facilitates a stable blood pressure, less need for vasopressors and fewer erythrocyte transfusions in the first week.
- Establishing a dedicated team facilitates optimal blood volume and specimen quality and without contamination when blood cultures are obtained.
Dr. Kaufman is a lead author of the clinical report and a member of the AAP Committee on Fetus and Newborn.
