Embolism occurs when a solid, liquid, or gaseous mass travels through the bloodstream and lodges in a blood vessel distant from the site of origin. Embolisms are classified based on direction of travel and composition. Pulmonary embolisms involve the lungs while systemic embolisms affect other organs. Common causes of embolism include blood clots, fat droplets, air bubbles, and infectious materials. Symptoms vary depending on the size and location of the embolism but may include dyspnea, chest pain, and coughing. Diagnosis involves blood tests, imaging, and scans. Consequences depend on factors like vessel size and collateral blood flow.

1. Embolism
DR. ROOPAM JAIN
PROFESSOR & HEAD
HOD DEPT. OF PATHOLOGY & BLOOD BANK

2. Introduction
• An embolus is intravascular solid, liquid or gaseous
mass that is carried by the blood to a site distant
from its point of the origin.

3. Classification of embolism
• 1. Based on the direction of movement of the
embolus
• 2. Pulmonary or systemic embolism
• 3. Composition of the emboli

4. • Orthograde embolism (direct embolism)- embolus is
carried in the direction of normal blood flow
• Retrograde embolism - the emboli move in a
direction opposite from the direction of blood flow;
this is usually significant only in blood vessels with
low pressure (veins) or with heavy emboli.
• Paradoxical embolism (<2%) - embolus that is
carried from venous side to the arterial side (or vice
versa). Example: septal defects in the heart (ASD,
VSD..), patent foramen ovale.

5. Composition of the emboli:
1. Thrombotic emboli
2. Fat droplets
3. Amniotic fluid emboli
4. Aterosclerotic emboli
5. Septic emboli
6. Air emboli

6. Pulmonary embolism
• 200,000 deaths per year in the USA
• In 95% of cases, venous emboli originate from deep
leg veins proximal to popliteal fossa
• It is the most common among hospitalized patients
• Their range in manifestations can be from mild to
lethal.
• Predisposing risk factors:
– prolonged bed rest, cancer, estrogen-based medication,
obesity, pregnancy, surgery, genetic factors increasing
blood clotting susceptibility...

7. Deep vein thrombosis

8. Virchow’s Triad

9. Direction of emboli

10. Symptoms and signs
• Symptoms and signs vary depending on the
diameter and number of blood vessels that are
occluded, part of the lungs that is affected and
other comorbidities
– Dyspnea
– Tachypnea
– Chest pain
– Cough
– Hemoptysis
– Tachycardia
PE is difficult to diagnose because
symptoms are non-specific and clinical
presentation of patients with suspected PE
varies widely from patients who are
asymptomatic to those in cardiogenic
shock

11. • Most pulmonary emboli are small and
clinically silent. If they are organized, they can
cause pulmonary hypertension
• Large embolus can cause death

13. Saddle pulmonary embolus
Gross description of large pulmonary emboli

14. Histopathology of tromboemboli

15. Cause of death:
• Acute cor pulmonale – form of acute right heart
failure produced by a sudden increase in resistance
to blood flow in the pulmonary circulation, and
dilatation of right side of the heart due to massive
(>60% of pulmonary circulation) or large emboli in
the pulmonary circulation.

16. Obstruction of the smaller blood vessels causes
pulmonary infarcts (if there is passive hiperemia
previously)

17. Diagnosing pulmonary embolism
• Blood test to look for a protein called D-dimer.
• CT pulmonary angiography (CTPA)
• ventilation-perfusion scan, also called a V/Q scan or
isotope lung scanning
• leg vein ultrasound

18. Systemic thromboembolism
• It will always lead to infarction in
the organs
• Common arterial embolization:
– Lower extremities (75%),
– central nervous system (10%),
– intestines, kidneys, spleen...

19. Systemic thromboembolism
• Causes:
– 80% arise from intracardiac mural thrombi (left ventricular
infarcts, or dilated left atria), aortic aneurysm, thrombi
overlying ulcerated atherosclerotic plaques, fragmented
valvular vegetations...

20. • Consequences of embolization depend on:
– the caliber of the occluded vessel
– The collateral supply
– The affected tissue’s susceptibility of oxygen
deprivation

21. Non-thrombotic emboli

22. Air embolism
• One or more air bubbles enter into vein or
artery and block them.

23. Causes
• Decompression disease:
– Acute: scuba divers -- when dissolved nitrogen
forms bubbles in body tissues and fluids causing
joint pain, weakness...
– Chronic: Caisson disease-pain in the bones due to
ishemic necrosis, neurologic and cardiovascular
deficits

24. • Iatrogenic:
Injections and surgical procedures (example:
brain surgeries and venous embolism..)
• Suicid

25. Morphology of air embolism
• Can be proved only at the autopsies
• There are bubles in blood vessels
• Air embolism can lead to acute cor pulmonale
• Heart and pulmonary vessels should be opened
under the water at the autopsy

26. Amniotic fluid embolism
• Complication of the labor
• Important cause of death among women in labor
(86%)
• Damage of placental membranes and rupture of the
uterine veins with entrance of squamous epithelial
cells of the skin into the blood

27. • Dyspnea, disseminated intravascular
coagulation, convulsion, coma
• Diagnosis is made when all other causes are
excluded

28. Fat embolism
• Develops after skeletal trauma, trauma of soft tissue,
burns
• Presence of fat globules in lung circulation and
peripheral circulation
• Usually occurs 72 hours after skeletal trauma
• Prevalence of fat embolism is 1% to 3.5% of patients
with fracture of tibia and femur

29. • Fat dropplets will travel through venous
circulation to the lungs and there they can
move to systemic circulation.
Oil red O, histochemical stain

30. • Fat particles enter the circulation and cause
damage to capillary beds. While the
pulmonary system is most frequently affected,
fat embolism can occur in the microcirculation
of the brain, skin, eyes, and heart can be
involved.

31. Fat embolism after blunt trauma
10.1007/s12024-018-0053-0

32. Brain: fat embolism

33. Lungs: fat emboli

34. Fat embolism
• 1. Mechanical theory
• 2. Biochemical theory (FFA toxic effects on the
endothelium)

35. Fat embolism syndrome
• 1% of patients with fat embolism can
develop this syndrome
• 24-72 hours after the injury
• Neurologic symptoms
• Heart and lung failure (ARDS)
• Anemia and thrombocytopenia

36. Septic embolism
• Obstruction of a blood vessel by embolus that is infected from
a distant infectious source.
• They lead to inflammation and abscessus formation.

37. Septic embolism
• Septic emboli are a common complication of infective
endocarditis.
• Septic emboli could affect multiple organs and cause variable
insults.
• Blood cultures are usually positive in patients with septic
emboli.
• Septic emboli cause tissue injury by two different mechanisms:
ischemia and infection.
• The prognosis of septic emboli usually depends on source
control of the underlying infection.

39. Embolism with foreign bodies
• Talc in drug users
• Silicone embolism
• Contaminated injections
• Endovascular procedures such as coiling,
catheterization, and thrombolysis may
contribute to lesion formation
• It can lead to granulomatous reaction

40. Histopathology of foreign body embolism

41. Signs and symptoms
• Asymptomatic
• Tiredness
• Weakness
• Pulmonary infarction, secondary infection

42. • Thank you for your attention