Pathology Cheat Sheet
When Perfusion Fails
Shock and thrombosis for NEET-PG: stages of shock, septic warm shock, Virchow triad, lines of Zahn, Factor V Leiden hypercoagulability, and DIC coagulopathy.
MedNext Academy | 3 min read
When Perfusion Fails
Shock and thrombosis for NEET-PG: stages of shock, septic warm shock, Virchow triad, lines of Zahn, Factor V Leiden hypercoagulability, and DIC coagulopathy.
The pathophysiology and stages of shock and the mechanisms of thrombosis under Virchow triad.
High-yield lines
- Shock is systemic circulatory failure with tissue hypoperfusion, defined by inadequate oxygen delivery rather than by blood pressure alone.
- The three main types are hypovolaemic, cardiogenic, and distributive shock, the last including septic and anaphylactic shock.
- Septic shock is triggered by microbial products such as Gram-negative endotoxin, causing massive cytokine release and vasodilatation.
- Early septic shock is warm with high cardiac output and low systemic vascular resistance, progressing to low output and multi-organ failure.
- The stages of shock are non-progressive (compensated), progressive, and irreversible.
- Virchow triad describes the three drivers of thrombosis: endothelial injury, abnormal blood flow (stasis or turbulence), and hypercoagulability.
- Lines of Zahn are alternating pale platelet-fibrin and dark red-cell layers indicating a thrombus formed in flowing blood during life.
- Postmortem clots lack lines of Zahn, are not attached to the vessel wall, and have a chicken-fat and currant-jelly appearance.
- Factor V Leiden is the most common inherited hypercoagulable state, caused by resistance to activated protein C.
- Acquired hypercoagulability includes malignancy (Trousseau syndrome), pregnancy, oral contraceptives, and antiphospholipid antibody syndrome.
- A thrombus can undergo propagation, embolisation, dissolution, or organisation and recanalisation.
- Disseminated intravascular coagulation combines widespread microthrombi with consumption of clotting factors producing bleeding.
Mapped competency codes
- PA6.3
- PA6.4
Continue into the full chapter
This summary maps to PA6-hemodynamic-disorders.
Frequently Asked Questions
What are the three components of Virchow triad?
Endothelial injury, abnormal blood flow (stasis or turbulence), and hypercoagulability, which together predispose to thrombosis.
What do lines of Zahn indicate?
They indicate a thrombus formed in flowing blood during life, showing alternating pale platelet-fibrin and dark red-cell layers, and are absent in postmortem clots.
How does early septic shock present haemodynamically?
As warm shock with high cardiac output and low systemic vascular resistance, before progressing to low cardiac output and multi-organ dysfunction.
What is the most common inherited cause of hypercoagulability?
Factor V Leiden mutation, which produces resistance to activated protein C and increases venous thrombosis risk.
Continue reading
Cheat SheetsAll Pathology cheat sheets
Browse the complete authored set for this subject.
Open the complete revision pathway
Explore clinician-written learning resources, structured revision and practice across the MedNext platform.
Open in the MedNext appSee plans