Sep 4, 2014 · An absence of urine, presence of blood in the collection bag, or flank pain may indicate that the tube is blocked. 24 If blockage is suspected it was recommended that nephrostomy tubes be irrigated or flushed using gentle force with normal saline or sterile water using sterile or aseptic technique. 4, 6, 9, 10, 24 Two documents stated that hand ...