(P-HC-9) Transfusion Audits, Peripheral Smears and the Future Path to Predictive Diagnostics in Post-Transplant Thrombotic Microangiopathy

Background/Case Studies:
Thrombotic microangiopathy (TMA), characterized by low platelet counts and microvascular thrombosis, affects up to 15% of renal transplant patients and leads to graft dysfunction and potential loss if not promptly managed. Platelet transfusions given to meet platelet count thresholds can worsen microvascular thrombosis in TMA. Peripheral smear evaluation for schistocytes is crucial for early diagnosis. This report presents how four routine platelet transfusion reviews assisted in the diagnosis of TMA in four renal transplant recipients due to reflexive peripheral smear review by the transfusion service.

Study

Design/Methods:
Daily platelet usage audits were performed. Patient charts were reviewed to assess the indication and response to transfusion. Peripheral blood smears were examined when a steep decline in platelet count was noted in a post renal transplant patient. Clinicians were immediately informed of the schistocyte results who initiated evaluation for TMA. Subsequent microbiology, coagulation testing, hemolysis markers, renal function, complement levels, ADAMTS13 activity, renal biopsy and imaging results were reviewed.

Results/Findings: All four patients presented with delayed graft function, acute kidney injury, and newly developed thrombocytopenia. Platelet audits revealed persistent thrombocytopenia despite transfusions (Figure 1A), and peripheral smears showed schistocytes (Figure 1B). Laboratory findings, including elevated LDH, low haptoglobin, and increased reticulocyte count, were consistent with hemolysis in all patients. Additional work-up- including microbiology, coagulation studies, complement levels, ADAMTS13 activity, and imaging- supported the diagnosis of thrombotic microangiopathy secondary to tacrolimus. Tacrolimus was discontinued in all cases and replaced with cyclosporine or belatacept in one patient. Two patients were treated with eculizumab. Both patients receiving eclulizumab showed improvement in platelet count, hemolysis markers and graft function. One patient has biopsy confirmed TMA (Figure 1C), while the other's biopsy were negative. Of the four patients, one patient progressed to graft failure.

Conclusions: These cases highlight the value of reflexive peripheral smear review when platelet transfusions are ineffective, enabling timely TMA diagnosis, appropriate intervention and preventing unnecessary transfusions. Renal biopsy may not be reliable in all cases. Looking ahead, machine learning tools trained on platelet trends, transfusion history, and clinical data could detect early signs of TMA in real time. As recent studies show, AI-assisted diagnostics have the potential to shift practice from reactive recognition to proactive intervention. Our findings emphasize both the current importance of transfusion audits and their future role in AI-driven care.