Catheterization of a target such as a stenotic area arising from a large patulous cavity can be extremely difficult. Occasionally, a loop may form when attempting to advance the catheter through the stenotic area, and this may result in losing access of the guide wire or catheter from the difficult target. For the past 40 years, one of us (I.F.H.) has attempted multiple strategies to correct the loop problem—usually without success. These strategies included the use of various catheters to reduce the loop, rapid forceful retraction of the guide wire and advancement of a tip deflector to the greater curvature of the loop, and retraction of the deflector. The deflector method will work if the tip of the catheter will advance in the distal target. By placing a snare catheter around the greater curvature of the loop and retracting the snare, the loop can be eliminated if, again, the tip will advance deeper into the target. Several years ago, a loop formed while placing a gastrojejunostomy catheter when the duodenum was very difficult to catheterize. Rather than pulling the loop with the snare catheter at the greater curvature of the loop, we advanced the snare around the entire loop close to the duodenum. When the snare was closed, the gastrojejunostomy catheter was “pinned” close to the target and could be retracted, reducing the loop without dislodging the tip—which was barely in the duodenal bulb. A snare is easily fabricated by simply placing a suture loop through any appropriately sized catheter. The disadvantage of this method is the requirement of a very large sheath or a very large dilated tract as in the case of gastrostomy access. We attempted to use this technique in a plastic model and, during experimentation, noted that the key to the technique was stabilizing the guide wire or catheter where it entered the target area (ureteropelvic junction, duodenum, etc) (Fig 1). The snare catheter will follow the course of the looped catheter or the guide wire to the area of the target (Fig 1a) in any large patulous cavity. The snare catheter is connected to the looped wire or catheter only at the tip (the snare) (Fig 1a). With the tip stabilized, the catheter or guide wire can be retracted without dislodging its tip (Fig 1). After the loop is reduced, the snare catheter can be removed (Fig 1b). During bench top experimentation, we found that a monorail catheter (Fig 2) could serve the same purpose as the snare but could more easily advance around the guide wire loop (Bentson 0.035-inch guide wire; Cook, Bloomington, Indiana) from 4 to 14 F with equally good results (4- and 5-F Cobra catheters, AngioDynamics, Queensbury, New York; 10.2- and 14-F multipurpose Ultrathane drainage catheters, Cook). To lock the monorail catheter to the looped guide wire, a second guide wire (Bentson; Cook) was placed through the lumen of the monorail catheter (Fig 2b). When the second wire engages the area where the looped wire enters the monorail, the second guide wire wedges against the looped guide wire and the two wires “lock” the looped wire to the catheter (Fig 2b). Wedging the wire is similar to closing the snare. Again, the monorail catheter is only attached to the looped guide wire, close to the target. With the guide wire stabilized, the loop can easily be retracted without dislodging its tip from the target (Fig 2c). After the loop is reduced (Fig 2c), the monorail catheter is removed (Fig 2c) and an attempt to place the intended catheter is resumed. Both techniques function equally well; however, again, the monorail catheter can easily be fabricated by placing a side hole close to the catheter's tip with either a small needle or a hole punch. A small catheter will usually advance over the looped wire without requiring a large sheath or tract. Both catheters can be homemade when the loop occurs or can be fabricated, sterilized, and readily available when this infrequent problem occurs.