The radiopaque ring from a ballard ercp cannula has come off the cannula tip and is on a guidewire which is threaded in this pt's papilla. This is the second time that the radiopaque metal ring fell off a cannula today while working in ercp. The first incident is when physician pulled out the cannula to groom the tip (give it more or less of a bend). The ring came off in hand. The next cannula worked well. In the next case, while doing an exchange of guidewire for cannula, the metal ring came off the cannula as the physician retracted the cannula and nurse advanced the guidewire. Photo was made of that ring as it slid down the guidewire. Briefly wedged the metal ring in the papilla but able to abort the procedure and remove the cannula and guidewire and have the metal ring from the tip of the cannula safely pass into the bowel of the pt to pass with stool. Since the only cannulas on hand were this series number, they aborted any further intervention. Rptr feels this run of production must be defective. Rptr suggests product pulled off the market before an incident occurs and the consumer product safety commission is notified.