There are predominantly two major dilatation techniques that are employed in dilating the cervix. The first technique uses expansible dry solid material, such as laminaria (seaweed) is inserted into the cervix in its dried stiff form. In the cervix it comes into contact with body fluids that cause the laminaria to swell and enlarge the cervical cavity. The second more widespread procedure, involves the use of series of solid, rod like instruments of graduated diameter used in serial fashion by the physician (Hegar dilators). The physician first inserts a rod like dilator and replaces it with the dilator of next higher diameter. This procedure continues until adequate dilatation occurs.