<Li> Thrombotic thrombocytopenic purpura </Li> <P> Nosebleeds are due to the rupture of a blood vessel within the richly perfused nasal mucosa . Rupture may be spontaneous or initiated by trauma . Nosebleeds are reported in up to 60% of the population with peak incidences in those under the age of ten and over the age of 50 and appear to occur in males more than females . An increase in blood pressure (e.g. due to general hypertension) tends to increase the duration of spontaneous epistaxis . Anticoagulant medication and disorders of blood clotting can promote and prolong bleeding . Spontaneous epistaxis is more common in the elderly as the nasal mucosa (lining) becomes dry and thin and blood pressure tends to be higher . The elderly are also more prone to prolonged nose bleeds as their blood vessels are less able to constrict and control the bleeding . </P> <P> The vast majority of nose bleeds occur in the anterior (front) part of the nose from the nasal septum . This area is richly endowed with blood vessels (Kiesselbach's plexus). This region is also known as Little's area . Bleeding farther back in the nose is known as a posterior bleed and is usually due to bleeding from Woodruff's plexus, a venous plexus situated in the posterior part of inferior meatus . Posterior bleeds are often prolonged and difficult to control . They can be associated with bleeding from both nostrils and with a greater flow of blood into the mouth . </P> <P> Sometimes blood flowing from other sources of bleeding passes through the nasal cavity and exits the nostrils . It is thus blood coming from the nose but is not a true nosebleed, that is, not truly originating from the nasal cavity . Such bleeding is called pseudoepistaxis (pseudo + epistaxis). Examples include blood coughed up through the airway and ending up in the nasal cavity, then dripping out . </P>

Where does the blood come from during a nosebleed
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