Methods and systems for detecting fluid egress, assessing lesion quality, determining tissue composition or structure, determining ice coverage of catheter tip and providing tissue contact assessment, by providing a catheter having a shaft with a proximal end portion and a distal end portion, the proximal end portion and the distal end portion define at least one fluid pathway therebetween with the shaft having a plurality of electrodes, positioning the catheter at a tissue treatment site, applying an electrical current between at least two of the plurality of electrodes, measuring impedance voltage between the at least two of the plurality of electrodes and, processing the measured impedance voltage caused by the applied electrical current to determine if fluid egress is present, to assess lesion quality, to determine tissue composition, ice cover of catheter tip, and to provide contact assessment. The system may have a control unit, a microprocessor, an impedance measuring device or the like to perform processing of impedance data.