Paper I
Question
Types of embolism
Answer
An embolus is a detached intravascular solid, liquid, or gaseous mass carried by the blood to a site distant from its point of origin, where it lodges and obstructs blood flow.
Pulmonary thromboembolism
- Most common type — originates from deep vein thrombosis (usually lower limb), travels via the venous system and right heart to lodge in the pulmonary arteries
Systemic thromboembolism
- Arises from thrombi in the heart (mural thrombus post-MI, atrial fibrillation) or arteries (atherosclerotic plaque), lodging in systemic arterial beds — brain, kidney, spleen, lower limbs
Fat embolism
- Release of fat globules into circulation, typically after fracture of long bones or soft tissue trauma; can cause fat embolism syndrome (respiratory distress, neurological symptoms, petechial rash)
Air embolism
- Introduction of air into the venous or arterial circulation (e.g., during obstetric procedures, chest wall injury, IV line disconnection); requires a significant volume (>100 mL) to cause clinically significant obstruction
Amniotic fluid embolism
- Entry of amniotic fluid (containing fetal cells, debris) into the maternal circulation during labour/delivery; a rare but often fatal obstetric emergency, causing acute respiratory distress and DIC
Decompression sickness (a form of gas embolism)
- Rapid decompression (e.g., deep-sea divers ascending too quickly) causes dissolved nitrogen to come out of solution as gas bubbles in blood and tissues
Tumour embolism
- Fragments of tumour tissue entering the circulation, contributing to haematogenous metastasis