This is an occasional result of the puerperal state, but sometimes it occurs as a result of tumours of the uterus, and even in affections of the neighbouring parts. The resulting condition is expressed by the clinical term Phlegmasia dolens. In the puerperal form the starting-point of the thrombosis is the placental surface of the uterus, and it is most apt to occur when, through imperfect contraction of the uterus, the veins are left with gaping mouths. It may be a question whether the introduction of septic material induces the coagulation, but in the usual absence of the general symptoms of septic poisoning it may be doubted whether this has to do at least with the extension of the coagulation. Starting at the uterus, the thrombosis readily extends to the iliac veins and onwards to the femoral and its branches.

The result is often an extensive thrombosis of the veins of the legs, generally beginning in those of the left side. There is usually a hard brawny cedema of the whole lower extremity.

Thrombosis here, as elsewhere, produces a chronic inflammation in and around the wall of the vein (Phlebitis and Periphlebitis), so that there is often considerable adhesion of the vein to its sheath and of the sheath to the parts around. The lymphatic vessels may be affected by this adhesion and partially obstructed.