Aim: To evaluate the longitudinal coagulation profile after allogeneic hematopoietic stem cell transplantation (HSCT) in pediatric patients with hematological malignancies.

Methods: Several coagulation variables were measured at predetermined time points for two years after HSCT in 30 pediatric patients.

Results: At six months post-HSCT, endothelial activation was reflected by 1.4-fold increase in circulating von Willebrand factor activity (p < 0.05), and by 2-fold increase in thrombin-antithrombin complex levels (p < 0.05), suggesting sustained coagulation system activity. In six patients with chronic graft-versus-host disease (cGVHD), specifically in those having gastrointestinal (GI) tract cGVHD, we observed continued longitudinal alterations in the coagulation system. The activities of both, coagulation factors (FV, FVII, FVIII, fibrinogen), and natural anticoagulants (antithrombin and protein C) were higher than prior to conditioning (p < 0.05) at most time points in patients with cGVHD. Moreover, fibrin turnover marker D-dimer was elevated from 6 to 18 months after HSCT (p < 0.05).

Conclusion: Pediatric patients undergoing HSCT demonstrate prolonged derangement of the coagulation system, with a new alleviating balance after 6 months post-HSCT. However, in patients with cGVHD, and in particular when cGVHD affects the GI tract, the persisting derangement of coagulation suggest its contributing role in cGVHD and related complications.