Platelet transfusions are often required to treat fetal and neonatal alloimmune thrombocytopenia (FNAIT), but evidence from a recently published study suggests that they may also lead to serious complications if administered too soon.
Risks and benefits of platelet transfusion therapy
In patients with FNAIT most platelet transfusions are performed before bleeding occurs, most guidelines recommend transfusions when platelet levels drop below a threshold of 30 × 10^9/L. Several studies affirm that platelet transfusions prevent hemorrhagic complications in patients with FNAIT.
However, other studies have questioned the benefits of platelet transfusions in thrombocytopenic patients without hemorrhagic clinical manifestations. Some studies in thrombocytopenic newborns with conditions other than FNAIT suggested that platelet transfusions had a limited effect on hemorrhage prevention and could produce severe adverse effects.
The PlaNeT-2 study, the largest clinical trial focusing on platelet transfusions in newborns, showed that patients who received platelet transfusions to prevent bleeding presented more complications than patients who only received platelets after presenting bleeding manifestations. Complications associated with platelet transfusions included neurodevelopmental delay, bronchopulmonary dysplasia, bleeding, and death. The study’s authors remarked that the reasons behind this phenomenon were unknown.
“Findings from the PlaNet-2 trial cautioned neonatologists against routinely prescribing platelet transfusions and suggested using more restrictive transfusion protocols,” the authors wrote.
Possible explanations for platelet transfusion complications
Newborn platelets differ significantly from adult platelets. In vitro, neonatal platelets are less active than adult platelets, however, most newborns don’t exhibit any bleeding manifestations due to lower platelet reactivity. Furthermore, neonates have several compensatory mechanisms to compensate for platelet hypo reactivity, like higher hematocrit and higher platelet volume.
Some authors hypothesize that this difference could lead to immune system malfunctions, some studies, for example, revealed that platelet transfusions increased proinflammatory cytokines in the blood.
Another potential mechanism is volume overload. Newborns have significantly less circulating blood than adults. Therefore, a transfusion could lead to volume overload, which in turn can compromise their cardiocirculatory system.
“Future research could focus on understanding the precise mechanisms behind the harmful effects associated with platelet transfusions and explore whether they convey any clinical benefit,” the authors concluded. “This understanding could help develop products or strategies to avoid these adverse effects.”
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