Background. Thrombocytopenia after orthotopic liver transplantation (OLT) is a well recognized and prevalent early postoperative complication. The etiology, as well as the effect of this phenomenon on transplant outcome, however, are vague. The aims of this study are to identify factors contributing to thrombocytopenia and to ascertain whether there is any correlation with early rejection and ultimate survival. Methods. This study examines 541 OLTs (541 grafts in 494 patients) that were transplanted at the University of Miami during the 3-year period from June 1994 to September 1997. The patients with severe postoperative thrombocytopenia (nadir platelet count [PLT] < 20,000/mm3), as well as the whole group of patients, were analyzed. The preoperative PLT, intra-operative platelet transfusion requirements, cross-match, recipient and donor cytomegalovirus (CMV) status, infusion of donor bone marrow cells (DBMC), occurrence of early rejection episodes (in the first posttransplant month), and re-transplantation were factors examined for any association with thrombocytopenia. Total bilirubin (TB) and direct bilirubin (dB), hematocrit, white blood cell count (WBC), aspartate aminotransferase and alanine aminotransferase, determined on the day that platelets reached a nadir (nadir day), were also analyzed. Results. In 90.9% of the cases, there was a 56.5% ± 23.5% fall in platelets in the immediate posttransplant period (first 2 weeks), but the mean PLT exceeded preoperative levels during the 3rd and 4th postoperative weeks. The nadir of the drop in the PLT most commonly occurred on posttransplant day 4. For preoperative PLT, platelet transfusions during the operation, re- transplantation, early rejection, cross-match, and recipient CMV status, there was significant statistical correlation with any degree of postoperative thrombocytopenia. Four of these factors, preoperative PLT, intra-operative platelet transfusions, retransplantation, and early rejection, were found to be independently associated with thrombocytopenia in general. None of them was found to be independently correlated with severe thrombocytopenia. A statistically significant correlation between bilirubin and WBC on the nadir day and the degree of thrombocytopenia was observed. No correlation was found between infusion of DBMC or donor CMV serology and thrombocytopenia. Both the nadir PLT and the percentage of the platelet fall were independent predictive factors (p<0.01 and 0.005, respectively) of patient and graft survival. Conclusions. Thrombocytopenia in the immediate posttransplant period is correlated with low preoperative PLT, massive platelet transfusions, and re-transplantation. These factors reflect a poor preoperative condition. There is also a correlation with allograft dysfunction, rejection, and poorer patient and graft survival. A rise in the mean PLT after the 2nd postoperative week reflects proper graft function.
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