Falsely low activated clotting time measured in a patient with sickle cell trait.

Sickle cell anaemia results from homozygosity of an A-T point mutation leading to a substitution of glutamic acid for valine at point 6 of the β-globin gene. A person with sickle cell trait inherits one normal and one mutated allele. Patients with sickle cell anaemia, and to a lesser extent sickle cell trait, have a wide spectrum of haemostatic abnormalities. Here we describe the problems faced in obtaining an accurate activated clotting time measurement, in a patient with sickle cell trait, prior to commencement of cardiopulmonary bypass for decannulation of Berlin Heart.