- intra-vascular coagulation of blood, usually in the presence of flowing blood

Thrombosis

- damaged blood vessel wall (atherosclerosis)

- Alterations in blood flow (stagnation, turbulence)

- Hypercoagulability (increased viscosity [high RBC,protein], platelets [thrombocytosis], thromboplastic [dead tissue/cancer], decreased fibrinolysis)

- Presence of Foreign Bodies

Initiating Factors of Thrombosis

- w/ high flow, the thrombosis consists of this

"pure" platelets and fibrin

w/ low flow, thromboses consist of this

Unifrom mixture of blood

- primary pathognomonic feature of thrombosis

- gray striations between red-purple RBC layers

- eosinophilic bands between layers of RBCs

Lines of Zahn

- thrombi containing infectious microorganisms

Septic thrombi

- thrombi lacking infectious organisms

Bland thrombi

- thrombi formed as a patch lining a vessel or a heart chamber wall

Mural thrombi

- nodular clumps of thrombi formed on cardiac valves

Vegetations

- Obstruction of vessel -> infarction

- Propagation (cont. activation of coagulation)

- Dissolution, Lysis (fibrinolysis liquefy thrombi)

- Embolization (detaching)

- Organization (thrombi -> vascular CT)

- Recanalization (larger channels)

Consequences of Thrombosis

- uniform red-purple, shiny, stretchy

- NO lines of Zahn

- before blood has a chance to settle

Non-thrombotic blood clot w/o settling

- two layers, both soft, shiny, stretchy

- NO lines of Zahn

- Top layer: plasma, tan-yellow (chicken-fat)

- Bottom layer: erythrocytes (uniform dark purple)

Non-thrombotic blood clot w/ settling

- extensive tissue injury, amniotic fluid embolism, neoplasms,infection or toxins

- causes consumption of clotting factors and platelets

- thrombocytopenia, long PT and PTT

- fragmented red cells (schistocytes)

- increased fibrin split products (FSPs)

Disseminated Intravascular Coagulation (DIC)

- thrombosis (little or no plasmin response) --> ischemia at multiple sites and organ failure

- hemorrhage (excessive plasmin response) --> consumption of platelets/clotting factors

Clinical Presentations of DIC

- intravascular migration of material acting as a solid, which is capable of impacting in and obstructing a blood vessel

Embolism

- crosses the sides of the circulatory system to affect a distant site on the opposite side

"Paradoxical" Migration

- Thrombus, Infection, Atherosclerotic debris, fat, bone marrow, gas, amniotic fluid, foreign bodies, tumor metastases

Embolization material

- material embolizing: thrombus

- from deep leg veins

- caused by stasis, injury, obstruction & hypercoagulability

- found in main pulmonary artery, bifurcation, smaller vessels

- causes sudden death if massive, infarction, no symptoms, pulmonary HTN

Pulmonary emboli

- origin from left side of heart, aorta, arteries (mural thrombi, a-fib, vegetations, aneurysms)

- Lodges in smaller arteries distal to site (cerebral, mesenteric, lower extremity, renal, rarely coronary)

- Causes infarction (large artery is catastrophic)

Arterial ("Systemic") emboli

- originates w/ injury to long bones w/ fatty marrow

- trauma, burns, pancreatitis, decompression sickness, DM

- lodges in lungs and brain

Fat Embolism

- occurs in 90% of pts w/ bone trauma

- less than 1% have symptoms

- syndrome includes respiratory distress syndrome, mental status changes, skin rash

- fat droplets in pulmonary capillaries, petechia in cerebral white matter

Fat Embolism Syndrome

- requires about 100 ml of air to produce clinical problems

- frothy mass occludes involved vessels

- enters via chest/neck wounds, IV/hemodialysis, dental procedures, uterine contractions during delivery

- lodges in right heart, pulmonary arteries, cerebral/coronary arteries (lung source)

Air Embolism

- originates w/ rapid variation in atmospheric pressure from hyperbaric to normobaric

- allows inert gases to dissolve in blood (Nitrogen), forms bubbles, embolize and lodge in arterioles

- "bends", "chokes", "blinds", "staggers"

- acute -> pain in joint/muscles, respiratory distress, mental status

- chronic -> aseptic necrosis of bones

Decompression sickness (Caisson Dx)

- rare complication of childbirth

- rupture of uterine veins and placental membranes leads to amniotic fluid into maternal circulation

- squamous cells, hair, fat

- Respiratory distress, shock, DIC

Amniotic fluid embolism