Editing Bleeding (section)

=== Medical condition ===
"Medical bleeding" denotes hemorrhage as a result of an underlying medical condition (i.e. causes of bleeding that are not directly due to trauma). Blood can escape from [[blood vessel]]s as a result of 3 basic patterns of injury:{{citation needed|date=June 2022}}
* [[blood|Intravascular changes]] — changes of the blood within vessels (e.g. ↑ [[blood pressure]], ↓ [[clotting factors]])
* [[blood vessel|Intramural changes]] — changes arising within the walls of blood vessels (e.g. [[aneurysms]], [[aortic dissection|dissections]], [[arteriovenous malformation|AVMs]], [[vasculitides]])
* Extravascular changes — changes arising outside blood vessels (e.g. [[Helicobacter pylori|''H pylori'']] infection, [[brain abscess]], [[brain tumor]])

The underlying scientific basis for blood clotting and hemostasis is discussed in detail in the articles [[blood coagulation|coagulation]], [[hemostasis]], and related articles. The discussion here is limited to the common practical aspects of blood clot formation which manifest as bleeding.

Some medical conditions can also make patients susceptible to bleeding. These are conditions that affect the normal hemostatic (bleeding-control) functions of the body. Such conditions either are, or cause, [[bleeding diathesis|bleeding diatheses]]. [[Hemostasis]] involves several components. The main components of the hemostatic system include [[platelets]] and the [[blood coagulation|coagulation]] system.

[[Platelets]] are small blood components that form a plug in the blood vessel wall that stops bleeding. Platelets also produce a variety of substances that stimulate the production of a blood clot. One of the most common causes of increased bleeding risk is exposure to [[nonsteroidal anti-inflammatory drugs]] (NSAIDs). The prototype for these drugs is aspirin, which inhibits the production of thromboxane. NSAIDs (for example Ibuprofen) inhibit the activation of [[platelets]], and thereby increase the risk of bleeding. The effect of aspirin is irreversible; therefore, the inhibitory effect of aspirin is present until the platelets have been replaced (about ten days). Other NSAIDs, such as ibuprofen (Motrin) and related drugs, are reversible and therefore, the effect on platelets is not as long-lived.{{citation needed|date=June 2022}}

There are several named coagulation factors that interact in a complex way to form blood clots, as discussed in the article on [[coagulation]]. Deficiencies of coagulation factors are associated with clinical bleeding. For instance, deficiency of Factor VIII causes classic [[hemophilia A]] while deficiencies of Factor IX cause "Christmas disease"([[hemophilia B]]). Antibodies to Factor VIII can also inactivate the Factor VII and precipitate bleeding that is very difficult to control. This is a rare condition that is most likely to occur in older patients and in those with [[autoimmune]] diseases. Another common bleeding disorder is [[Von Willebrand disease]]. It is caused by a deficiency or abnormal function of the "Von Willebrand" factor, which is involved in platelet activation. Deficiencies in other factors, such as factor XIII or factor VII are occasionally seen, but may not be associated with severe bleeding and are not as commonly diagnosed.

In addition to NSAID-related bleeding, another common cause of bleeding is that related to the medication [[warfarin]] ("Coumadin" and others). This medication needs to be closely monitored as the bleeding risk can be markedly increased by interactions with other medications. Warfarin acts by inhibiting the production of [[Vitamin K]] in the gut. Vitamin K is required for the production of the clotting factors, II, VII, IX, and X in the liver. One of the most common causes of warfarin-related bleeding is taking antibiotics. The gut bacteria make vitamin K and are killed by antibiotics. This decreases vitamin K levels and therefore the production of these clotting factors.

Deficiencies of platelet function may require platelet transfusion while deficiencies of clotting factors may require transfusion of either [[fresh frozen plasma]] or specific clotting factors, such as [[Factor VIII]] for patients with hemophilia.