Afterdrop is a continued cooling of a patient's core temperature during the initial stages of rewarming from hypothermia. Afterdrop is attributed to the return of cold blood from the extremities to the core due to peripheral vasodilatation, thus causing a further decrease of deep body temperature. However a second theory explains afterdrop as a side effect of conductive heat transfer. "The hypothermic patient cools from the outside in. Consequently, a heat gradient is established from the relatively warm core to the cool periphery. This heat gradient does not reverse immediately upon initiation of rewarming. Until the gradient is reversed, further heat transfer occurs from the warmer core to cooler peripheral tissues."