Insufficient fibrinogen response following free flap surgery is associated with bleeding complications

Background: Microvascular tissue transfer has become a safe and reliable tool in the reconstructive armamentarium, yielding high success rates. However, little is known about the changes in coagulation after free tissue transfer and their potential impact on morbidity. Methods: Fibrinogen concentration and platelet count among other values were available and assessed in 139 undergoing free tissue transfer before, immediately after, and 1-3 as well as 8-11 days after surgery. In patients undergoing urgent revision for either bleeding or microvascular thrombosis, blood samples were drawn directly before re-exploration. Results: In the patients without any surgical revision and in those with thrombosis of the microvascular pedicle, both fibrinogen concentration and platelet count increased significantly during the early and late post-operative window. Patients that developed bleeding necessitating re-exploration showed an inadequate increase in fibrinogen levels, resulting in significantly lower concentrations compared to the other two groups. There were no significant differences in platelet count or PTT between these groups. Conclusion: Free flap surgery induces acute and subacute changes in coagulation, comparable to other major surgeries and severe injuries. This leads to an increase in platelet count and fibrinogen over the post-operative course. Patients that developed bleeding requiring surgical re-exploration showed an insufficient increase in fibrinogen, resulting in significantly lower fibrinogen levels. Therefore, monitoring and correction of fibrinogen levels might aid in preventing or treating bleeding complications following free flap surgery.