Undulate is a clinical symptom, allowing to determine the presence of fluid in large cavity (ascites, large cyst and others).
The principle of undulate is the transfer of oscillations of the liquid from one wall of the cavity to the other. Call undulate as follows: the palm of one hand flat is placed on the skin in the area of fluid retention, and ends bent fingers of the other hand glides jerky blow from the opposite side. The impetus caused fingers passed through the liquid, is perceived by hand. The definition of undulate can be difficult thick layer of subcutaneous fat, over-voltage cysts, a small amount of liquid. Cm. also Zublena.