Haemolytic and Uraemic Syndrome (HUS) is a serious disease requiring rapid diagnosis and management. The atypical HUS diagnosis has been greatly improved by anti-CS antibody (Eculizumab) wich block alternative complement pathway activation. To rise treatment success, Eculizumab introduction should be as early as possible. In some secondary HUS (infection, drugs…) complement is also involved as second-hit. To date, there is no tool to confirm complement involvement in a HUS at diagnosis stage. This study suggest to evaluate a therapeutic orientation test, in order to determine the complement implication in HUS diagnosis. The test evaluates the complement deposits on endothelial cell surface in vitro, compared to a normal human serum. In order to determine the test performance, first the positive or negative results will be compared to the HUS clinical evolution, treated or not by the clinician with Eculizumab. Second, the test results will be compared to the presence of alternative complement pathway regulation abnormalities.