A patient transferred to the PCU after CABG surgery develops thrombocytopenia. What is the most likely cause?

The most likely cause of thrombocytopenia in a patient who has undergone CABG surgery and is now in the progressive care unit is heparin-induced thrombocytopenia (HIT). HIT is a serious immune-mediated reaction to heparin where antibodies form against complexes of heparin and platelet factor 4, leading to platelet activation and a paradoxical increase in thrombotic events, alongside a decrease in platelet counts.

In the context of CABG surgery, patients are often administered heparin both during and after surgery for anticoagulation. The occurrence of thrombocytopenia typically arises within 5 to 14 days after exposure to heparin, especially if the patient has a history of prior heparin exposure. Monitoring platelet levels postoperatively is crucial, and a significant drop in platelets can indicate HIT.

While other options may have valid connections to thrombocytopenia, they do not represent the most common or likely cause post-CABG in the presence of heparin. For instance, platelet dysfunction from the use of a pump could contribute to issues but is less likely to specifically account for a significant decrease in platelet count. Bone marrow suppression is a possible cause but not typical following CABG without other contributing