Bleeding may result from abnormalities in
Blood vessels
Vascular bleeding disorders result from defects in blood vessels, typically causing petechiae, purpura, and bruising but, except for hereditary hemorrhagic telangiectasia Hereditary Hemorrhagic Telangiectasia Hereditary hemorrhagic telangiectasia is a hereditary disorder of vascular malformation transmitted as an autosomal dominant trait affecting men and women. (See also Overview of Vascular Bleeding... read more 
, seldom leading to serious blood loss. Bleeding may result from deficiencies of vascular and perivascular collagen in Ehlers-Danlos syndrome Ehlers-Danlos Syndrome Ehlers-Danlos syndrome is a hereditary collagen disorder characterized by articular hypermobility, dermal hyperelasticity, and widespread tissue fragility. Diagnosis is clinical. Treatment is... read more 
and in other rare hereditary connective tissue disorders (eg, pseudoxanthoma elasticum Pseudoxanthoma Elasticum Pseudoxanthoma elasticum is a rare genetic disorder characterized by calcification of the elastic fibers of the skin, retina, and cardiovascular system. Diagnosis is clinical. There is no specific... read more 
, osteogenesis imperfecta Osteogenesis Imperfecta Osteogenesis imperfecta is a hereditary collagen disorder causing diffuse abnormal fragility of bone and is sometimes accompanied by sensorineural hearing loss, blue sclerae, dentinogenesis... read more 
, Marfan syndrome Marfan Syndrome Marfan syndrome consists of connective tissue anomalies resulting in ocular, skeletal, and cardiovascular abnormalities (eg, dilation of ascending aorta, which can lead to aortic dissection)... read more 
). Hemorrhage may be a prominent feature of scurvy Vitamin C Deficiency In developed countries, vitamin C deficiency can occur as part of general undernutrition, but severe deficiency (causing scurvy) is uncommon. Symptoms include fatigue, depression, and connective... read more or of immunoglobulin A–associated vasculitis Immunoglobulin A–Associated Vasculitis (IgAV) Immunoglobulin A–associated vasculitis (formerly called Henoch-Schönlein purpura) is vasculitis that affects primarily small vessels. It occurs most often in children. Common manifestations... read more 
, a hypersensitivity vasculitis common during childhood.
In vascular bleeding disorders, results of tests of hemostasis Laboratory Tests of Hemostasis by Phase 
are usually normal. For most disorders, diagnosis is clinical; specific tests are available for some.
