A position sensing system includes a probe adapted to be introduced into a body cavity of a subject. The lasso-shaped probe includes a magnetic field transducer in the rigid section proximal to the flexible lasso-shaped distal section which has at least one probe electrode. A control unit is configured to measure position coordinates of the probe using the magnetic field transducer. The control unit also measures an impedance between the at least one probe electrodes and one or more points on a body surface of the subject. Using the measured position coordinates, the control unit calibrates the measured impedance and provides an indication of the deformation and deflection of the flexible lasso-shaped distal section in relation to the magnetic field transducer in the rigid proximal section.