Continuous flow resectoscopes. Are the theory and design wrong?

The optical design of rod-lens telescopes has now reached a zenith. The only way of improving the resectoscope is to investigate the ergonomics and flow dynamics. We present a comparative analysis of the flow mechanics of continuous flow resectoscopes. The morphology, flow characteristics and irrigating potential (washout gradient) of several instruments were examined. It was found that when used with balanced continuous flow (inflow and outflow balanced), all of the endoscopes had poor visibility compared with unbalanced continuous flow (inflow > outflow). Possible changes in the design of the instruments are discussed.