The essential lesion is the absence or deficiency of valves, so that they are incompetent and fail to support the column of blood which bears back upon them.  Normally the valves in the femoral and iliac veins and in the inferior vena cava are imperfectly developed, so that in the erect posture the great saphena receives a large share of the backward pressure of the column of venous blood.

The whole length of the vein may be affected, but as a rule the disease is confined to one or more segments, which are not only dilated, but are also increased in length, so that they become convoluted.  The adjacent loops of the convoluted vein are often bound together by fibrous tissue.  All the coats are thickened, chiefly by an increased development of connective tissue, and in some cases changes similar to those of arterio-sclerosis occur.  The walls of varicose veins are often exceedingly brittle.  In some cases the thickening is uniform, and in others it is irregular, so that here and there thin-walled sacs or pouches project from the side of the vein.  These pouches vary in size from a bean to a hen’s egg, the larger forms being called venous cysts, and being most commonly met with in the region of the saphenous opening and of the opening in the popliteal fascia.  Such pouches, being exposed to injury, are frequently the seat of thrombosis (Fig. 66).

[Illustration:  FIG. 66.—­Thrombosis in Tortuous and Pouched Great Saphena Vein, in longitudinal section.]

Clinical Features.—­Varix is most frequently met with between puberty and the age of thirty, and the sexes appear to suffer about equally.

The amount of discomfort bears no direct proportion to the extent of the varicosity.  It depends rather upon the degree of pressure in the veins, as is shown by the fact that it is relieved by elevation of the limb.  When the whole length of the main trunk of the great saphena is implicated, the pressure in the vein is high and the patient suffers a good deal of pain and discomfort.  When, on the contrary, the upper part of the saphena and its valves are intact, and only the more distal veins are involved, the pressure is not so high and there is comparatively little suffering.  The usual complaint is of a sense of weight and fulness in the limb after standing or walking, sometimes accompanied by actual pain, from which relief is at once obtained by raising the limb.  Cramp-like pains in the muscles are often associated with varix of the deep veins.

The dilated and tortuous vein can be readily seen and felt when the patient is examined in the upright posture.  In advanced cases, bead-like swellings are sometimes to be detected over the position of the valves, and, on running the fingers along the course of the vessel, a firm ridge, due to periphlebitis, may be detected on each side of the vein.  When the limb is oedematous, the outline of the veins is obscured, but they can be identified on palpation as gutter-like tracks.  When large veins are implicated, a distinct impulse on coughing may be seen to pass down as far as the knee; and if the vessel is sharply percussed a fluid wave may be detected passing both up and down the vein.