Abstract: A method for determining agglutination of a biological liquid by measuring a change in hydrodynamic resistance of the biological liquid flowing through a microfluidic channel of a microfluidic device, comprising the steps of: a) calibrating the microfluidic device; b) filling the microfluidic reaction channel with a hydrophobic continuous liquid phase, c) introducing a first reference droplet; d) causing the first reference droplet to flow; e) measuring the time of flow of the first reference droplet; f) introducing a second reference droplet followed by a sequence of test droplet(s); g) causing the second reference droplet and the sequence of test droplet(s) to flow; h) measuring the time of flow; i) calculating the hydrodynamic resistance of the sequence of the test droplet(s); and j) determining agglutination of the biological liquid by comparing the hydrodynamic resistance with the calibrated values.