What does the term "retrograde" refer to in a medical context?

In a medical context, the term "retrograde" refers specifically to moving or occurring against the normal direction of flow, particularly in respect to bodily fluids or processes. For instance, in the context of blood circulation, "retrograde" would describe the movement of blood moving backwards in the circulatory system as opposed to the regular, forward flow. This term can apply to various medical procedures and evaluations, such as retrograde pyelography, where a contrast dye is injected against the flow of urine into the kidneys for imaging purposes. Understanding this term is crucial for recognizing its implications in diagnostics and treatments within medical practice.