In 1953, researchers at the University of North Carolina first described the partial thromboplastin time test. The test assessed the intrinsic and common pathways of coagulation. It became widely used to investigate clotting disorders and monitor heparin treatment.

The partial thromboplastin time first described in 1953 made heparin therapy safer by turning invisible clotting activity into measurable time. In cultural terms, it is part of the modern medical conversion of danger into numbers, charts, and waiting, influencing poets to explore the intersection of science and human emotion.