Neutrophils are responsible for destroying bacteria, eosinophils respond to parasitic worms and allergens, lymphocytes destroy cancerous or infected cells, and monocytes phagocytize pathogens and debris.

Mast cell functions in allergic responses by release histamine and other chemicals that promote inflammation. Macrophages are part of the innate immune system and function to engulf and remove debris. Neutrophils are also part of the innate immune system and have macrophagic properties, especially when fighting bacterial infection. Natural killer cells bind to and destroy pathogens without the use of antigens.

Lymphedema (commonly just "edema") is an excessive buildup of fluid in the body's tissues caused by a failure of the lymphatic system to properly balance fluids. The causes vary widely—from poor diet to malignant cancers—and it is usually seen as part of a wider constellation of symptoms. Lymphedema is also a common complication of surgery.

Buerger's disease commonly affects small arteries, veins, and nerves, narrowing the channels through which blood flows and causing ischemia (lack of blood supply) to the extremities. Long associated with tobacco exposure, the disease can cause gangrene and lead to amputation of the fingers, toes, hands and feet its most severe form.

Although Pratt's test is not part of Wells' criteria, it is used to screen for DVT's. It involves squeezing the patient's popliteal vein, in the symptomatic leg. A test is considered positive if it causes pain. The other answers listed are part of Wells' criteria.

Kawaski disease is a rare childhood disease that is a form of vasculitis. The walls of blood vessels throughout the body become inflamed with no known cause. It cannot be prevented, but most children recover after a few weeks.

Raynaud's disease is a rare disorder that cause the arteries of the body to have episodes of vasospasms. These vasospasms affect blood flow to the finger and toes most often. The disorder is often managed by minor lifestyle changes.

Sickle cell disease is inherited red blood cell disorders, which cause abnormal hemoglobin to be created. This hemoglobin is known as "hemoglobin S" or sickle hemoglobin. The incorrect structure of the hemoglobin S causes a reduction the red blood cell's ability to travel through blood vessels and transport oxygen to tissues. It also causes the classic "donut" shaped red blood cell to bend due to an amino acid substitution on the periphery of the hemoglobin protein from a hydrophilic one to a hydrophobic one. Anemia is a broad term and can be a result of multiple causes.

An aneurysm is a balloon-like bulge in an artery. Often, these occur in the aorta or arteries in the brain. An aneurysm does not necessarily mean the artery has ruptured. Treatments for aneurysms focus on reducing the chances of the vessel rupturing, such as medications to lower blood pressure or surgery to repair the vessel's wall. 

Atherosclerosis is a disease in which plague begins to form in the arteries, which limits the ability of blood to flow through the area. Also the plaque makes the arterial walls less elastic, which increases blood pressure. Plague can build up in any area of the body, although the pulmonary circuit is much less prone to developing atherosclerotic signs. Atherosclerosis can lead to an increased risk of several health problems, including heart attacks and chronic kidney disease.