Clot strength: A comparison between cord and adult blood by means of thrombelastometry

Objective: To evaluate the clot strength in cord versus adult blood. Method: Thrombelastometry (TEM) was the method of choice as it provides information on the clot strength in terms of the maximum clot firmness (MCF) and on the fibrin polymerization process in terms of the clot formation time and the a angle. Results: The MCFs were significantly lower in cord versus adult platelet rich plasma (PRP, 63.0 +/- 3.8 vs. 67.0 +/- 3.9mm, P = 0.006) and in cord versus adult whole blood (WB, 55.3 +/- 3.8 vs. 59.3 +/- 3.6 mm, P = 0.001) employing the thrombelastometry with extrinsic activator assay. We suggest that the diminished clot strength in cord versus adult blood and plasma samples is attributable to an impaired polymerization of neonatal fibrin: (i) the thrombelastometry with extrinsic activator and inactivated platelets (FIBTEM) assay revealed significantly lower MCFs in cord versus adult PRP (23.0 +/- 3.1 mm vs. 27.3 +/- 3.9 mm, P = 0.002) and in cord versus adult WB (11.6 +/- 2.3 mm vs. 15.3 +/- 3.3 mm, P < 0.001); (ii) the a angle in the FIBTEM assay was significantly lower in cord versus adult WB (39.0 +/- 12.8 degrees vs. 55.5 +/- 12.3 degrees, P = 0.02); (iii) the clot formation times in the FIBTEM assay were significantly longer in cord versus adult PRP (248.0 +/- 143.5 s vs. 81.5 +/- 39.8 s, P = 0.001). Conclusions: Neonatal fibrin shows impaired polymerization properties under our experimental conditions resulting in reduced clot strength compared with fibrin of adult origin.