The amount of a phosphatidylethanolamine O-16:1_18:2 when measured in blood serum. The trait is level of Phosphatidylethanolamine (O-16:1_18:2) in blood serum (Ontology of Biological Attributes term OBA_2045144). Also known as: blood serum phosphatidylethanolamine O-16:1_18:2 amount, level of phosphatidylethanolamine O-16:1_18:2 in blood serum.