Deep vein thrombosis
Deep vein thrombosis is the formation of a blood clot ("thrombus") in a deep vein
Deep vein
Deep vein is a term used to describe a vein that is deep in the body. It is used to differentiate deep veins from veins which are close to the surface, also known as superficial veins....

. Deep vein thrombosis commonly affects the leg
Łęg may refer to the following places in Poland:*A former name for the town of Ełk *Part of the Czyżyny district of Kraków*Łęg, Pleszew County in Greater Poland Voivodeship...

 veins (such as the femoral vein
Femoral vein
In the human body, the femoral vein is a blood vessel that accompanies the femoral artery in the femoral sheath. It begins at the adductor canal and is a continuation of the popliteal vein...

 or the popliteal vein
Popliteal vein
The popliteal vein course runs alongside the popliteal artery but carries the blood from the knee joint and muscles in the thigh and calf back to the heart.Its origin is defined by the junction of the posterior tibial vein and anterior tibial vein....

) or the deep veins of the pelvis
In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

. Occasionally the veins of the arm
In human anatomy, the arm is the part of the upper limb between the shoulder and the elbow joints. In other animals, the term arm can also be used for analogous structures, such as one of the paired forelimbs of a four-legged animal or the arms of cephalopods...

 are affected (such as in Paget-Schrötter disease). A DVT can occur without symptoms, but in many cases the affected extremity will be pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...

ful, swollen
Swelling (medical)
In medical parlance, swelling is the transient enlargement or protuberance in the body and may include tumors. According to cause, it may be congenital, traumatic, inflammatory, neoplastic or miscellaneous....

, red, and warm, and the superficial veins may be engorged.