platelet aggregation test, a blood test that can detect diseases that affect either platelet number or function, thereby prolonging bleeding time. This test can provide information about prolonged platelet aggregation times, connective tissue disorders such as lupus erythematosus, recent cardiopulmonary or dialysis bypass, various myeloproliferative diseases, primary protein disease, von Willebrand’s disease, uremia, and congenital disorders such as Wiskott-Aldrich syndrome, Bernard-Soulier syndrome, and glycogen storage disorders.