A surgical instrument, such as an endoscopic or laparoscopic instrument, includes an ablation device. The ablation device includes an elongate member having first and second channels. First and second probes are disposed within the respective first and second channels. The first and second probes each define a central axis. The first and second probes each have substantially straight distal ends protruding from the distal ends of the respective first and second channels. The substantially straight distal ends define an outer surface. First and second electrodes are attached to a portion of the outer surface of the substantially straight distal ends of the respective first and second probes. The first and second electrodes are positioned in juxtaposed relationship with the central axis of the first and second probes. A distance between the first and second electrodes is adjustable by rotating at least one of the first and second probes about the respective central axis of the at least one of the first and second probes.