The Importance of Pseudo Thrombocytopenia Due to Platelet Cold Agglutination before Surgery, What Should We Do? A Case Report

Platelet cold agglutination (PCA) is a rare in-vitro phenomenon caused by Immunoglobulin M (IgM) autoantibodies, which results in Ethylenediaminetetraacetic Acid (EDTA) independent pseudo thrombocytopenia (PTCP). Its diagnosis is made based on the peripheral blood smear (PBS) examination and pre-test warming blood sample. Here, a case of PTCP secondary to PCA is presented. He was first admitted for pre-surgical tests but his platelet count was low. His blood was taken with EDTA and sodium citrate anticoagulant to rule pre-analytical error out. Then his sample warmed up and the test was run again with Mindray BC-6000 automated cell counter. Moreover, the rheumatologic tests were done for him. His platelet count was 23×10^9/L at first, and PBS showed many platelet aggregates. The low platelet count was not correct with Sodium Citrate or re-sampling with EDTA so platelet satellitism and improper sampling were ruled out. By warming the sample up to 37⸰C, the Platelet count rose to 216×10^9 / L. The rheumatologic tests were negative except for HLA-B27 which was positive. Finally, he was diagnosed with PCA which is due to a cold antibody (clinically insignificant). This diagnosis is important for the prevention of recurrent tests, unnecessary platelet transfusion, and other problems. Here these conditions will be discussed.