Pathology: Blood or qi deficiency. This is seen in cases of deficiencies and failure of Qi and blood. It can also be seen in disharmonies of the even emotions, weakness in Yang Qi, internal damage to jing, and penetration of dampness.
Testing for venous blood clots. Venous blood clots may be detected in a variety of ways, though ultrasound is most commonly used. Occasionally, the patient's size and shape limit the ability for ultrasound to provide a definitive answer. Venography is an alternative test to look for a clot.
Blood tests: Sometimes, a blood test is used to screen for blood clots. D-dimer is a breakdown product of a blood clot, and levels of this substance may be measured in the bloodstream. Blood clots are not stagnant; the body tries to dissolve them at the same time as a new clot is being added.