Blood Clots

Symptoms, Doctors, Treatments, Research & More

Condition 101

What is the definition of Blood Clots?

Blood clots are clumps that occur when blood hardens from a liquid to a solid.

  • A blood clot that forms inside one of your veins or arteries is called a thrombus. A thrombus may also form in your heart.
  • A thrombus that breaks loose and travels from one location in the body to another is called an embolus.

A thrombus or embolus can partly or completely block the flow of blood in a blood vessel.

  • A blockage in an artery may prevent oxygen from reaching the tissues in that area. This is called ischemia. If ischemia is not treated promptly, it can lead to tissue damage or death.
  • A blockage in the vein will often cause fluid buildup and swelling.

What are the alternative names for Blood Clots?

Clot; Emboli; Thrombi; Thromboembolus; Hypercoagulable state

What are the causes for Blood Clots?

Situations in which a blood clot is more likely to form in veins include:

  • Being on long-term bed rest
  • Sitting for long periods, such as in a plane or car
  • During and after pregnancy
  • Taking birth control pills or estrogen hormones (especially in women who smoke)
  • Long-term use of an intravenous catheter
  • After surgery

Blood clots are also more likely to form after an injury. People with cancer, obesity, and liver or kidney disease are also prone to blood clots.

Smoking also increases the risk of forming blood clots.

Conditions that are passed down through families (inherited) may make you more likely to form abnormal blood clots. Inherited conditions that affect clotting are:

  • Factor V Leiden thrombophilia
  • Prothrombin G20210A mutation

Other rare conditions, such as protein C, protein S, and antithrombin III deficiencies.

A blood clot may block an artery or vein in the heart, affecting the:

  • Heart (angina or a heart attack)
  • Intestines (mesenteric ischemia or mesenteric venous thrombosis)
  • Kidneys (renal vein thrombosis)
  • Leg or arm arteries
  • Legs (deep vein thrombosis)
  • Lungs (pulmonary embolism)
  • Neck or brain (stroke)


Anderson JA, Hogg KE, Weitz JI. Hypercoagulable states. In: Hoffman R, Benz EJ, Silberstein LE, et al, eds. Hematology: Basic Principles and Practice. 7th ed. Philadelphia, PA: Elsevier; 2018:chap 140.

Schafer AI. Thrombotic disorders: hypercoagulable states. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 176.

Top Global Doctors

Flora Peyvandi
Midori Shima
Kashihara-shi, 29, JP
Johannes Oldenburg
Bonn, NW, DE
Michael A. Laffan
London, ENG, GB

Latest Research

Latest Advance
  • Condition: Stage T1b Papillary Thyroid Carcinoma (PTC)
  • Journal: Zhonghua er bi yan hou tou jing wai ke za zhi = Chinese journal of otorhinolaryngology head and neck surgery
  • Treatment Used: Transoral Vestibular Approach vs. Bilateral Areola Approach (BAA) vs. Endoscopic and Open Thyroidectomy (OT)
  • Number of Patients: 178
  • Published —
This study compared the surgical effectiveness and cosmetic satisfaction of the transoral endoscopic thyroidectomy by vestibular approach (TOETVA), endoscopic thyroidectomy via bilateral areola approach (BAA), and open thyroidectomy (OT) in the treatment of papillary thyroid carcinoma (PTC) stage T1b.
Latest Advance
  • Condition: Knee Osteoarthritis
  • Journal: Pain research & management
  • Treatment Used: Ultrasound-Guided Radiofrequency
  • Number of Patients: 256
  • Published —
In this study, researchers evaluated the safety and effectiveness of ultrasound-guided radiofrequency for the treatment of chronic pain due to knee osteoarthritis.