A number of ureteral stone dislodgers and extractors have been devised in the past few years. In the majority of these, the device that traps the stone has made the caliber of the whole instrument so great that it is passed by the obstructing calculus with difficulty.
To secure an instrument with the smallest diameter possible, I designed the dislodger described here:
It consists of a number 1 or a 2 bougie. One and one-half inches from the tip of the bougie there are attached four stout threads of Japanese silk (tooth silk). These are made fast to the bougie core by very fine silk threads wrapped about their ends, as shown in figure 1. This attachment of the threads to the core marks the greatest diameter in the entire instrument. The point of attachment is spindle shaped so as to pass by the stone with the maximum of ease.