Fig. 5. A. A 4-0 nylon ligature is placed within the lumen of the tube. Entry is from the reservoir end of the tube. B. A 6-0 Vicryl external ligature is tied around the tube, close to the tube-plate junction. It is tied in a way that does not completely occlude outflow. C. Testing irrigation with the balanced salt solution allows the surgeon to feel resistance to outflow. A wet cell sponge shows that some fluid is leaking around the intraluminal suture onto the reservoir plate. The small 6-0 Vicryl suture is loosened if it is too tight.