A medical probe device including a catheter having a stylet guide housing with one or more stylet ports in a side wall thereof and guide means for directing a flexible stylet outward through the stylet port and through intervening tissue to a target tissue. The catheter assembly includes a stylet guide lumen communicating with the stylet port and a stylet positioned in said stylet guide lumen for longitudinal movement from the port through intervening tissue to a target tissue. The stylet can be an electrical conductor enclosed within a non-conductive layer, the electrical conductor being a radio frequency electrode. In normal action, the stylet and its surrounding sleeve are deployed out from the stylet port in the catheter into the desired target tissue. A sharpened tip on the stylet electrode facilitates the penetration of the intervening tissue, such as a urethra. If, however, the stylet is deployed into a dense or fibrous area of tissue or into an area of scar tissue in the urethra, the sharpened tip of the stylet might not immediately penetrate the urethra wall until sufficient pressure is applied to the stylet. By heating the stylet prior to extension of the stylet from the stylet port in the catheter, the passage of the stylet through the intervening tissue is facilitated. Once the stylet is in position in the target tissue, the normal operation of the stylet in emitting electromagnetic current for tissue ablation is commenced.