Evaluation of urinary catheters for effective manual bladder washout

Our purpose was to evaluate the efficiency of manual bladder washout (MBW) for bladder retention by blood clot formation using urinary catheters. Three types of 22 Fr urinary catheters, a rounded tip Foley catheter (FC) with the standard two eyes, an open-ended Nelaton catheter (NC) with a side hole, and an open-ended Foley catheter (OEFC) with a side hole closer to the tip than NC, were evaluated. An automatic irrigation device that could perform a predetermined procedure mimicking MBW under constant velocity was fabricated. The procedure using catheters and the device was performed in a pseudo blood clot or in water. The total area of the holes was the largest in NC followed by FC and OEFC. The predetermined operations using our device revealed that NC needed less force and could effectively remove pseudo clots from the early stage of the operations. Fluid visualization experiments suggested that a closer distance between the tip and the side hole could improve the efficiency of clot removal. In conclusion, the larger the area of the hole in urinary catheter, the less force is required for MBW. Furthermore, the most efficient catheter with two holes for MBW needs to be at least open-ended with a side hole closer to the tip.