Patient with pulmonary embolism one week ago now she developed pitting edema in her both leg only without any other abnormality so what is the cause?

Pulm hypertension. After a pulmonary embolism, (blood clot in the lungs) there can be high blood pressure in the lungs, (pulmonary hypertension) causing the blood to back up into the leg veins. An echocardiogram could help to find this out. Blood clots in legs is possible, but less likely since both legs are involved. A blockage of the veins in the pelvis is possible too. You should see your doctor about this soon. .