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Updated: May 24, 2026

Pre-Chiasmatic, Single Injection of Autologous Blood to Induce Experimental Subarachnoid Hemorrhage in a Rat Model
Published on: June 18, 2021
Reduced clot-stability during the first 6 hours after aneurysmal subarachnoid haemorrhage--a prospective case-control
Carl C Larsen1, Benny Sørensen, Jørn D Nielsen
1Department of Neurosurgery, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark. larsen-cc@hotmail.com
Introduction:
Early rebleeding is an important cause of death and disability following aneurysmal subarachnoid haemorrhage (SAH). Recent studies have shown that 50-90% of the rebleedings occurred within the first 6 hours after the primary bleeding. The mechanism leading to rebleeding remains to be established. In the present prospective case-control study we hypothesize that patients with SAH develop a coagulopathy characterized by reduced clot stability during the early period after the initial bleeding.
Methods:
Patients with aneurysmal SAH was studied with a dynamic clot lysis assay and markers of fibrinolysis and clot stabilizers in blood samples taken within and after 6 hours after onset of bleeding. Results were compared with blood samples from age and gender matched healthy controls.
Results:
36 patients were enrolled, 26 patients had blood samples collected within 6 hours after the initial bleeding whereas 10 patients had blood samples taken later than 6 hours after the initial bleeding. Patients demonstrated significantly reduced clot stability during the first 6 hours after initial bleeding. Fibrinolytic activity was increased during the first 6 hours along with the inhibitors of fibrinolysis whereas the modulators of fibrinolysis were reduced or inactivated.
Conclusion:
During the first 6 hours after SAH patients exhibit reduced clot-stability. Probably a consequence of activated fibrinolysis in combination with reduced or inactivated factor XIII and thrombin-activable fibrinolysis inhibitor.
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