Retrograde flow, also commonly referred to as black flow, is the undesirable phenomenon in which fluid, mixed with tissue cells, bodily fluid and blood, moves up the jet stream and enters the jet injector, contaminating the internal fluid pathway and drug reservoir.
The following illustrations demonstrate this concept. In the first image, the jet injector is actuated and the jet stream is emitted from the nozzle.
In this image, the jet stream is deposited into the arm.
Near the end of jet injection process, the pressure of the jet stream impinging the skin would be less than the pressure of the fluid deposited within the newly constructed hole in the vaccinee’s arm. Since the jet stream was too weak to further deepen the hole, it moved backwards and flowed out of the hole and back into the jet injector. This would be an expected phenomenon in almost every jet injection due to the continuous depletion of pressure. The image below demonstrates the multi-directional flow, in which tissue cells, blood and bodily fluids, flowed into the jet injector orifice.
And where is the evidence?