Haemorrhage
How blood escapes from vessels: through a tear, an eroded wall or leaky small vessels; how bleeds are named by size and site; why volume, speed and site decide the danger; and what happens to blood left in the tissues.
By the end, you can
- Describe how an intact vessel wall and haemostasis normally keep blood inside the vessels.
- Distinguish haemorrhage by rupture, by erosion and by diapedesis, with typical causes of each.
- Use the terms for bleeds by size, cavity and route, from petechiae and haematomas to haemothorax and melaena.
- Explain why the volume, speed and site of a bleed decide its effects, from shock to tamponade and raised intracranial pressure.
- Describe what happens to blood in the tissues: breakdown to bilirubin and haemosiderin, organisation and cyst formation.
- Recognise the classic appearances of bleeds, the classes of acute blood loss and the tests that find the cause, and explain how stopping the bleeding, replacing blood and reversing anticoagulants act on the mechanism.
What it is
Haemorrhage is the escape of blood from the heart or vessels, out of the body (external) or into tissues and body cavities (internal). Blood leaves through a tear in the wall (rupture), through a wall eroded from outside, or by red cells seeping through small vessels (diapedesis). Its effect depends on how much blood is lost, how fast and where it goes.
3 types to tell apart
- By source
- Arterial (bright red, spurting with each beat), venous (darker, steady flow) or capillary (oozing from a raw surface).
- By mechanism
- Rupture of the wall (rhexis), erosion of the wall from outside (diabrosis) or diapedesis through small vessels.
- By speed
- Acute (large losses over minutes to hours, with a risk of shock) or chronic (small losses over months, leading to iron deficiency).
US spelling: haemorrhage → hemorrhage, haemostasis → hemostasis.
Normal function
Walls and clots keep blood inside
An artery’s wall resists the pressure inside it: the is lined by endothelium, the and the smooth muscle of the take the strain, and the collagen of the stops it overstretching. Capillaries are a single layer of endothelium on a basement membrane, held together by junctions that keep red cells in.
Small breaks happen every day and are sealed by haemostasis: the injured vessel constricts, platelets stick to exposed collagen and form a plug, and the coagulation cascade lays a mesh of fibrin over it. Healthy endothelium keeps all of this switched off elsewhere, and fibrinolysis later clears the clot.
Underlying change · Step 1 of 5
Torn, eroded or leaky: how blood gets out
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 2 of 5
Naming a bleed by size, cavity and route
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Disrupted function · Step 3 of 5
How much and how fast
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 4 of 5
Where it goes: small bleeds in closed spaces
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Consequences · Step 5 of 5
What happens to blood left in the tissues
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Symptoms and signs
Symptoms, signs and findings
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Exam detail
Exam detail
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Treatment
How treatment works
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Recap
Recap
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .
Self-check
Check your understanding
The full lesson is part of Student Pro
It takes you through all 5 steps of the mechanism, explains the symptoms, signs and findings each step causes, adds the exam detail and how treatment works where the lesson has them, then recaps it and lets you check yourself with 10 self-check questions. The full pathophysiology library: guided lessons with self-check questions comes with Student Pro, with 100 tutor answers a month and the full available catalogue.
Free to read: the introduction and .