Hemorrhage
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- For the band, see Haemorrhage (band).
Hemorrhage (AE) or haemorrhage (BE) is the medical term for bleeding. In common usage, a hemorrhage means particularly severe bleeding; although technically speaking it refers to any type of bleeding.
Types of hemorrhages
- Intracerebral hemorrhage - bleeding in the brain caused by the rupture of a blood vessel within the head. See also hemorrhagic stroke.
- Subarachnoid hemorrhage (SAH) implies the presence of blood within the subarachnoid space from some pathologic process. The common medical use of the term SAH refers to the nontraumatic types of hemorrhages, usually from rupture of a berry aneurysm or arteriovenous malformation(AVM). The scope of this article is limited to these nontraumatic hemorrhages.
- Intracranial hemorrhage
- Hypertensive hemorrhage
- Cerebral hemorrhage
- Postoperative hemorrhage
- Postpartum hemorrhage
- Arterial hemorrhage - from an artery
- Venous hemorrhage - from a vein
- Capillary hemorrhage - from a capillary
- Primary hemorrhage - if bleeding immediately follows an injury
- Reactionary hemorrhage - delayed bleeding after injury
- Secondary hemorrhage - delayed bleeding from sepsis
- Hematuria - blood in the urine from urinary bleeding
- Hemoptysis - coughing up blood from the lungs
- Hematemesis - bleeding in the stomach
Causes, incidence, and risk factors
Hemorrhage generally becomes dangerous, or even fatal, when it causes hypovolemia (low blood volume) or hypotension (low blood pressure). In these scenarios various mechanisms come into play to maintain the body's homeostasis. These include the "reverse-stress-relaxation" mechanism of smooth muscle, the baroreceptor reflex and renal and endocrine reseponses such as the renin - angiotensin - aldosterone effect.
Death from hemorrhage can generally occur surprisingly quickly. This is because of 'positive feedback'. An example of this is 'cardiac depression', when poor heart contraction depletes blood flow to the heart, causing even poorer heart contraction. This kind of effect causes death to occur more quickly than expected.
Hemorrhage in the brain
Internal bleeding can occur in any part of the brain. Blood may accumulate in the brain tissues itself, or in the space between the brain and the membranes covering it. The bleeding may be isolated to part of one hemisphere (lobar intracerebral hemorrhage) or it may occur in other brain structures, such as the thalamus, basal ganglia, pons, or cerebellum (deep intracerebral hemorrhage).
An intracerebral hemorrhage can be caused by a traumatic brain injury or abnormalities of the blood vessels (aneurysm or angioma). When it is not caused by one of these conditions, it is most commonly associated with high blood pressure (hypertensive intracerebral hemorrhage). In some cases, no cause can be found.
Blood irritates the brain tissues, causing swelling (cerebral edema). It can collect into a mass called a hematoma. Either swelling or a hematoma will increase pressure on brain tissues and can rapidly destroy them.
Symptoms vary depending on the location of the bleed and the amount of brain tissue affected. The symptoms usually develop suddenly, without warning, often during activity. They may occasionally develop in a stepwise, episodic manner or they may get progressively worse.
See also
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