Thrombin, Fibrin Monomer and Factor XIII in Patients with Unexplained Intraoperative Bleeding.

To explore relevant changes in unexplained intraoperative bleeding, we evaluated elements of the final steps of the coagulation cascade in 226 consecutive patients undergoing elective surgery. Patients were stratified for the occurrence of unexplained intraoperative bleeding according to predefined criteria.

Twenty patients (8.8%) developed unexplained bleeding. Median intraoperative blood loss was 1350 ml (bleeders) and 400 ml (non-bleeders), p<0.001. Fibrinogen and factor XIII were more rapidly consumed in bleeders (p<0.001). Soluble fibrin formation (fibrin monomer) was elevated in bleeders throughout surgery (p < 0.014, table 1). However, F. XIII availability per unit thrombin generated was significantly decreased in bleeders pre-, intra- and postoperatively (p < 0.051). Computerized thrombelastography showed a parallel, significant reduction in clot firmness.

We suggest that a mild, pre-existing coagulopathy is not rare in surgical patients and probably can result in clinically relevant intraoperative bleeding. This haemostatic disorder shows impaired clot firmness, probably secondary to decreased cross-linking (due to a loss of F. XIII, both in absolute measures and per unit thrombin generated).

We are currently conducting a double blind, randomized trial on the use of F. XIII early during surgery. We suggest that the preoperative measurement of fibrin monomer concentration might allow preoperative risk stratification for intraoperative blood loss.

Fibrin Monomer is increased in “bleeders”