An apparatus for fragmenting a stone includes an endoscope, a laser fiber, a sheath and a detection feedback system. The endoscope includes a working channel. The working channel is configured to have a retrieval basket inserted therethrough. The sheath may include a first lumen and a second lumen. A first one of the lumen is connected to the endoscope with a shaft of the endoscope extending through the first lumen. A second one of the lumen is spaced from the shaft of the endoscope providing a channel proximate an exterior side of the shaft. The second lumen has the laser fiber inserted therethrough. The detection feedback system is configured to deliver a low energy check pulse from the laser fiber and detect a response, and configured to at least partially control delivery of a high energy laser pulse from the laser fiber to cause the stone to fragment.