الفهرس 
Introduction &aim of workOnly 14 pages are availabe for public view
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Abstract
Children with aplastic anemia and cancer have bleeding tendency due to thrombocytopenia; they receive frequent platelets transfusion but most of them became refractory to transfusion.We aimed to study the frequency of platelet refractoriness among the hematologic and oncologic patients in Ain Shams University- Pediatric Hospital- Hematology-oncology unit .To identify the determinants of platelet refractoriness including the immune causes by evaluating the antiplatelets antibodies and the non-immune causes related to patients, platelets and disease related problems.
A cross sectional study was be performed including 60 children with onco-hematologic diseases necessitating platelets transfusions and admitted at Ain-Shams university pediatrics hospital hematology-oncology unit. Exclusion of patients with immune platelets disorders. They were divided 2 groups:patients with thrombocytopenia secondary to aplastic anemia and secondary to childhood cancer.
Revision of hospital records for diagnosis and its date, history of platelet transfusion ,bleeding, its site and severity, number of platelets transfusions prior to testing, drugs used with emphasis on amphotericin B/vancomycin/ ciprofloxacin.Full clinical examination was done and laboratory investigations including complete blood picture prior to platelet transfusion, 1 hour post transfusion, and 18-24 hours after transfusion with calculation of platelets increments and corrected count increment .Poor response to platelets transfusion was considered if CCI is less than 5000. Patients sera collected before transfusion to detect anti platelet antibodies by platelets immunofluorescence test using flowcytometry.
Oncology group were 26 children with mean age ±SD 7.67±4.59 years , 14 females (53.8%) and 12 males (46.2%) and aplastic group were 32 children with mean age 10.03±4.65 years, 13 females (40.6%) and 19 males (59.4%).52.9% of the oncohematological patients have CCI <5000 .There was no significant difference between patients with CCI above and below 5000 as regard gender, diagnosis, type of platelet transfused, blood group, age , frequency of transfusion, frequency of fever or use of concurrent use of vancomycin , ciprofloxacin or amphotericin use .CCI was lower in patients using vancomycin (P=0.029) and with different blood groups (P=0.012).We had a mean platelets increment of 27.04 and 22.77 in the one and 18-24 hours in the oncology group and 13.28 and 9.07 x 10 9/L in the aplastic group (P=. Aplastic group had higher frequency of transfusion (P=0.010)and longer duration since diagnosis (P=0.013) and lower use of single donor platelets(P˂0.001).No significant correlation found between Ab% and CCI at 1h post transfusion and at 18-24 hours post transfusion in oncology & aplastic patients. The best cut off point for antibody levelsbetween positive and negative patients was found > 11.3 with a sensitivity of 96.55% and specificity of 100%.
We conclude that using a non-leuco-reduced platelets products we had a frequency of poor platelets response to transfusion of 52 %. Platelets antibodies were not correlated with platelets increments. Patients with aplastic anemia had a higher levels of antibodies compared to children with cancer probably due to higher use of random platelets preparation and higher frequency of previous transfusions. CCI was lower in children using vancomycin.