A cooled radiofrequency ablation system comprising: a probe assembly comprising a hollow elongated shaft extending from a handle at a proximal end of the probe assembly to a distal tip region of the probe assembly, the hollow elongated shaft defining an internal cavity having a first internal cooling fluid tube and a second internal cooling fluid tube positioned therein, the first internal cooling fluid tube extending a first distance from the handle and the second internal cooling fluid tube extending a second distance from the handle, the second distance being greater than the first distance, and the distal tip region comprising a conductive portion for delivering energy to a target location within tissue; a radiofrequency generator for delivering energy to the target location via the conductive portion of the distal tip region of the probe assembly; a cooling device including a cooling fluid reservoir and a bidirectional pump assembly operable to circulate a cooling fluid through the probe assembly; and a controller configured to operate the bidirectional pump assembly in a first operating mode and a second operating mode based on a user selection, wherein: in the first operating mode, the bidirectional pump assembly rotates in a first direction to transfer the cooling fluid from the cooling fluid reservoir through the first internal cooling fluid tube, the internal cavity, the second internal cooling fluid tube, and back to the cooling fluid reservoir, in the second operating mode, the bidirectional pump assembly rotates in a second direction to transfer the cooling fluid from the cooling fluid reservoir through the second internal cooling fluid tube, the internal cavity, the first internal cooling fluid tube, and back to the cooling fluid reservoir, and the first operating mode produces a first size of lesion and the second operating mode produces a second size of lesion that is larger than the first size of lesion by allowing the generator to apply greater amounts of RF energy without causing unwanted increase in local tissue temperature in the second operating mode. a probe assembly comprising a hollow elongated shaft extending from a handle at a proximal end of the probe assembly to a distal tip region of the probe assembly, the hollow elongated shaft defining an internal cavity having a first internal cooling fluid tube and a second internal cooling fluid tube positioned therein, the first internal cooling fluid tube extending a first distance from the handle and the second internal cooling fluid tube extending a second distance from the handle, the second distance being greater than the first distance, and the distal tip region comprising a conductive portion for delivering energy to a target location within tissue; a radiofrequency generator for delivering energy to the target location via the conductive portion of the distal tip region of the probe assembly; a cooling device including a cooling fluid reservoir and a bidirectional pump assembly operable to circulate a cooling fluid through the probe assembly; and a controller configured to operate the bidirectional pump assembly in a first operating mode and a second operating mode based on a user selection, wherein: in the first operating mode, the bidirectional pump assembly rotates in a first direction to transfer the cooling fluid from the cooling fluid reservoir through the first internal cooling fluid tube, the internal cavity, the second internal cooling fluid tube, and back to the cooling fluid reservoir, in the second operating mode, the bidirectional pump assembly rotates in a second direction to transfer the cooling fluid from the cooling fluid reservoir through the second internal cooling fluid tube, the internal cavity, the first internal cooling fluid tube, and back to the cooling fluid reservoir, and the first operating mode produces a first size of lesion and the second operating mode produces a second size of lesion that is larger than the first size of lesion by allowing the generator to apply greater amounts of RF energy without causing unwanted increase in local tissue temperature in the second operating mode. in the first operating mode, the bidirectional pump assembly rotates in a first direction to transfer the cooling fluid from the cooling fluid reservoir through the first internal cooling fluid tube, the internal cavity, the second internal cooling fluid tube, and back to the cooling fluid reservoir, in the second operating mode, the bidirectional pump assembly rotates in a second direction to transfer the cooling fluid from the cooling fluid reservoir through the second internal cooling fluid tube, the internal cavity, the first internal cooling fluid tube, and back to the cooling fluid reservoir, and the first operating mode produces a first size of lesion and the second operating mode produces a second size of lesion that is larger than the first size of lesion by allowing the generator to apply greater amounts of RF energy without causing unwanted increase in local tissue temperature in the second operating mode.