Thrombocytopenia after isolated limb or hepatic perfusions with melphalan;The risk of heparin-induced thrombocytopenia

Background: Three cases of heparin-induced thrombocytopenia (HIT) were obse rved in patients undergoing isolated limb perfusion (ILP) with melphalan. T his occurrence prompted the discontinuation of prophylactic postoperative h eparin in ILP patients and its avoidance in patients undergoing isolated he patic perfusion (IHP). The need to reassess these decisions led to a review of thrombocytopenia in both patient populations. Methods: Records of all patients treated with ILP or IHP at our institution from July 1992 through November 1996, were reviewed. Nine IHP patients wer e tested prospectively for heparin-related antibodies using serum samples o btained perioperatively and during the second postoperative week. Results: Thrombocytopenia (<100,000 platelets/mu L) developed postoperative ly in 30% of 131 ILP patients and in 77% of 56 IHP patients. No cases of HI T were identified other than the three who had been previously diagnosed. T he prevalence of HIT in heparinized ILP patients was 2.8% (3/108). All nine IHP patients developed heparin-related antibodies postoperatively. Conclusions: Because the prevalence of HIT following ILP is in the range ob served in other clinical settings, postoperative heparin prophylaxis is an option. However, it probably should be limited to the first week, and daily platelet counts should be reviewed for a pattern of thrombocytopenia consi stent with HIT. The prevalence of heparin-related antibodies after IHP is s o high that prophylactic heparin should be avoided in this setting.