Unveiling the Hemostatic Signature of Prematurity: A Prospective Rotational Thromboelastometry-Based Analysis.

: The evaluation of the haemostatic mechanism in premature neonates remains particularly challenging, due to their immature haemostatic system, the influence of inflammation and the variety of clinical factors. This prospective study aimed at (a) assessing the haemostatic profile of clinically stable preterm neonates by Rotational Thromboelastometry [ROTEM; (EXTEM, INTEM, FIBTEM assays)], (b) establishing reference ranges, and (c) investigating potential differences in comparison to healthy term neonates. We also evaluated the impact of clinical and perinatal factors on the haemostatic status of this vulnerable population. : 69 premature neonates with no underlying morbidity and 226 healthy term neonates were the study subjects. In term neonates, blood was collected on the 2nd-3rd day of life, if sampling was required for any other reason (hyperbilirubinemia, ABO blood group incompatibility screening, maternal thyroid antibodies, or insufficient prenatal care), whereas in premature neonates, blood was collected between the 4nd-10th day after stabilisation. The parameters measured for each ROTEM assay included Clotting Time (CT), Clot Formation Time (CFT), Alpha angle (α, degrees), Clot Amplitude at 5 and 10 min (A5, A10), Maximal Clot Firmness (MCF), and Lysis Index at 30, 45 and 60 min (Li30, Li45, and Li60 respectively). : The data analysis demonstrated a prothrombotic profile in preterm neonates, characterized by increased values of A5, A10, (MCF), and α-angle, and shortened CT and CFT across all assays (EXTEM, INTEM, FIBTEM), when compared to term neonates. A statistically significant inverse correlation was observed between gestational age and clot lysis parameters (INTEM Li45, Li60). Additionally, hematocrit levels were negatively correlated with clot amplitude and kinetics of clot development, while platelet count was positively associated with clot firmness parameters (A5, A10, MCF) and α-angle. Mode of delivery and the presence of gestational diabetes did not significantly affect ROTEM assay values. Preterm neonates with a history of respiratory distress syndrome (RDS) exhibited a more pronounced hypercoagulable profile compared to those without RDS, as reflected by the enhanced clot strength and reduced CT, findings that may be attributed to postnatal pulmonary inflammation and its systemic effects on coagulation. : This study introduces for the first time reference values for the parameters of ROTEM assays (EXTEM, INTEM, FIBTEM) in clinically stable preterm neonates-a highly vulnerable patient group with a distinct need for accurate and individualized monitoring of their haemostatic status. The combined assessment of these assays enhances diagnostic precision, and offers a more comprehensive evaluation of neonatal haemostasis. By defining reference ranges in whole blood, this work provides novel data that support the integration of ROTEM into clinical transfusion algorithms.