Deep Vein Thrombosis

(Part 2) 

Description of DVT

Arteries are the blood vessels that carry oxygen-rich blood from the heart to all other parts of the body. Veins return the oxygen-depleted blood back to the heart. There are two types of veins in the body:

• Superficial veins lie just below the skin’s surface

• Deep veins are located deep within the muscles

Deep vein thrombosis (DVT) occurs when a blood clot (thrombus) forms within one of the deep veins. While DVT can occur in any deep vein, it most commonly occurs in the veins of the pelvis, calf, or thigh.

 Causes of DVT

Several factors can affect blood flow in the deep veins and increase the risk for developing blood clots. These include:

• Increasing age

• Personal or family history of DVT or pulmonary embolism

• Having cancer

• Having a vein disease, such as varicose veins

• Smoking

• Using birth control pills or hormone therapy

• Pregnancy

• Being overweight or obese

• Inheriting a blood-clotting disorder

A broken hip or leg, or having major surgery on your hip, knee or lower leg can affect normal blood flow and clotting. In these orthopedic situations, three primary factors contribute to the formation of blood clots in veins: slow blood flow, hypercoagulation, and damage to the veins.

Blood that Flows Slowly through Veins (Stasis)

The walls of the veins are smooth. This helps blood flow freely and mix with naturally occurring agents (anticoagulants) in the blood that keep the blood cells from clotting. 

Blood that does not flow freely and does not mix with anticoagulants may be more likely to clot. 

This is why it is important to watch for signs of DVT in people who are on bed rest, immobilized in a splint or cast, or not able to move for long periods of time. 

Hypercoagulation

Blood thickens, or coagulates, around matter that does not belong in the veins. During surgery, matter such as tissue debris, collagen, or fat may be released into the blood system and can cause the blood to coagulate. In addition, during total hip replacement, preparing the bone to receive the prosthesis may cause the body to release chemical substances called antigens into the blood system. These antigens can also stimulate clot formation.