A case report of sudden thrombocytopenia detected only by in vitro analysis.

We experienced an unexpected thrombocytopenia detected only in vitro during radical prostatectomy for a 66-year-old patient. Thrombocytopenia with platelet aggregation was observed in a blood sample obtained using a heparinized syringe (not by ethylene diamine tetra-acetic acid tube). Although we could not exclude platelet agglutination in vivo, no thrombosis or coagulation disorder was observed. We changed the anti-coagulant in the arterial catheter carrier fluid (saline) from heparin to argatroban, and continued with the operation. No embolic complications were observed during the perioperative period. Although pseudothrombocytopenia or heparin-induced thrombocytopenia was highly suspected in the present case, we were not able to confirm which of the two developed. Multi-directional attention and care may be required for perioperative unexpected thrombocytopenia.