In anal vein thrombosis (AVT) (synonyms: Anal thrombosis, perianal thrombosis, perianal vein thrombosis, perianal thrombosis; ICD-10-GM K64.5) is a thrombus (blood clot) in one of the subcutaneous (“under the skin“) veins of the caudal haemorrhoidal plexus in the region of the anus.
Anal vein thrombosis refers to thrombosis of a perianal vein (as opposed to acute hemorrhoidal thrombosis: Thrombosis (obstruction of a blood vessel by a clot) of one or more hemorrhoidal nodes).
Sex ratio: men are more commonly affected than women.
Frequency peak: the maximum incidence of anal venous thrombosis is in middle adulthood.
Course and prognosis: Untreated or with conservative therapy (without surgery), anal thrombosis resolves over the course of days to weeks. Ulceration of the skin covering the thrombosis may also occur as a result of pressure necrosis (death of tissue due to permanent pressure), with the consequence of spontaneous departure of the thrombus (coagulum; blood clot). This usually leads to a sudden reduction of pain. The duration of the disease is about one to two weeks. Anal vein thrombosis is often recurrent (recurring).
