Reference ranges of thromboelastometry in healthy full-term and pre-term neonates

Rotational thromboelastometry (ROTEM) is an attractive method for rapid evaluation of hemostasis in neonates. Currently, no reference values exist for ROTEM assays in full-term and pre-term neonates. Our aim was to establish reference ranges for standard extrinsically activated ROTEM assay (EXTEM) in arterial blood samples of healthy full-term and pre-term neonates.

In the present study, EXTEM assay was performed in 198 full-term (≥37 weeks' gestation) and 84 pre-term infants (<37 weeks' gestation) using peripheral arterial whole blood samples.

Median values and reference ranges (2.5th and 97.5th percentiles) for the following main parameters of EXTEM assay were determined in full-term infants: clotting time (seconds), 41 (range, 25.9-78); clot formation time (seconds), 70 (range, 40-165.2); maximum clot firmness (mm), 66 (range, 41-84.1); lysis index at 60 min (LI60, %), 97 (range, 85-100). The only parameter with a statistically significant difference between full-term and pre-term neonates was LI60 (p=0.006). Furthermore, it was inversely correlated with gestational age (p=0.002) and birth weight (p=0.016) in pre-term neonates.

In conclusion, an enhanced fibrinolytic activity in pre-term neonates was noted. For most EXTEM assay parameters, reference ranges obtained from arterial newborn blood samples were comparable with the respective values from studies using cord blood. Modified reagents, small size samples, timing of sampling, and different kind of samples might account for any discrepancies among similar studies. Reference values hereby provided can be used in future studies.