System and method for detecting and counting bacteria suspended in a biological fluid by means of light scattering measurements is provided. In accordance with the method of the invention the level of signal to noise of the measured intensities of light scattered by a sample of the biological fluid is significantly enhanced for forwardly scattered light within a range of scattering angles which are smaller compared to a predefined maximal scattering angle. The system of the invention includes a cuvette adapted to contain a sample of the biological fluid whose sidewalls and windows are suitably constructed and arranged to significantly reduce the level of reflected light obscuring the scattering patterns measured within the range of scattering angles considered.