We present a theoretical study of the impact of an electric field combined with a magnetic field on the rotational dynamics of open-shell diatomic molecules. Within the rigid rotor approximation, we solve the time-independent Schrodinger equation including the fine-structure interactions and the -doubling effects. We consider three sets of molecule-specific parameters and several field regimes and investigate the interplay between the different interactions identifying the dominant one. The possibility of inducing couplings between the spin and rotational degrees of freedom is demonstrated.