The laser diffractoscope - a new and fast system to analyse red blood cell flexibility with high accuracy.

Red blood cell (RBC) flexibility is one of the determining parameters of the microcirculation. As capillaries are smaller in diameter than RBC, RBC can only pass through by deformation. Reduced flexibility is associated with a reduced microcirculation. In obstetrics, pre-eclampsia and intrauterine growth retardation are regarded as diseases exhibiting a reduced microcirculation. With this new system it might be possible to achieve new data concerning the microcirculation in these diseases. The laser diffractoscope is based on laser light diffraction and computer-assisted image analysis. It offers the ability to determine the flexibility of RBC in whole blood with high accuracy between 0 and 30 Pa. Two hundred microlitres of whole blood are required, and the analysis is carried out in less than 5 min, with a standard deviation < or =1%. The laser diffractoscope is a new system which offers the ability to measure RBC deformability with high accuracy in a short time. Evaluation of reproducibility and validity, as well as comparison with data from other measuring systems, proves the excellence of the laser diffractoscope. An example of its application is shown by analysing the deformability of RBC in 10 uncomplicated pregnancies at term.