Perianal thrombosis is one of the most frequent causes of consultation in colo-proctology. Despite its high incidence, this condition has received little attention in the literature and its pathophysiology is still a matter of controversy. A prospective study was performed with eighty consecutive patients with perianal thrombosis in order to define clinical aspects, associated conditions and potential implications to its pathophysiology. Forty-five patients (56%) were able to detect some possible causal agents, particularly strong physical effort (32%). Sixty-four patients (80%) refered normal bowel habits. Previous symptoms of hemorrhoidal disease were reported by only eight patients (10%) and no evidence of hemorrhoidal disease by anoscopy was found in 55 patients (69%). Forty-one patients (51 %) had experienced previous episodes o perianal thrombosis. Microscopic evaluation of the three excised specimens showed an intravascular position of the clot. We conclude from this study that perianal thrombosis is not related to hemorrhoidal disease. 1t is also suggested that the pathophysiology of perianal thrombosis may be related to sudden increases in intra-abdominal pressure leading to anal sphincter contraction, obstruction of subdermal veins of the anal canal and formation of an intravascular clot.
Perianal thrombosis; Perianal hematoma; Hemorrhoids