Excellent! CORRECT! You have it exactly. Water retention = edema, where is fluid-block is what you said. So much fluid in an area that the Qi movement is disrupted. I have done this to myself before by drinking/eating too many cold things. Suddenly my stomach sounds like there is water in it when I move and I can actually hear it splashing around. Have you done this to yourself before? That might help you remember it. That being said, that is just a mild, acute situation if it is warmed up right away. If someone has chronic cold/Yang Def, this can allow fluid to accumulate due to lack of circulation and warming/condensing of fluids over the long-term. This majorly disrupts Qi flow!