A Perianal hematoma is a type of hematoma located in, or on the border of the anus. It can be misdiagnosed as a hemorrhoid, but is sometimes referred to as an external hemorrhoid.
Perianal hematoma is caused by the rupture of a small vein that drains blood from the anus. This rupture may be caused by heavy lifting, coughing, straining, or bicycle riding. Once the rupture has formed, blood quickly pools within a few hours and, if left untreated, forms a clot.
A burst Perianal Blood Vessel causes an Perianal Hematoma, or "external haemorrhoid".
The symptoms of a perianal hematoma can present over a short period of time. Pain, varying from mild to severe, will occur as the skin surrounding the rupture expands due to pressure. This pain will usually last even after the blood has clotted, and may continue for two to four days.