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Acta Cir Bras. 2006 Sep-Oct;21(5):354-6.

Hemorrhoids: an experimental model in monkeys.

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Department of Surgery, Federal University of São Paulo (UNIFESP), São Paulo, Brazil.



Hemorrhoids are a matter of concern due to a painful outcome. We describe a simple, easy and reliable experimental model to produce hemorrhoids in monkeys.


14 monkeys (Cebus apella) were used. After general anesthesia, hemorrhoids were induced by ligation of the inferior hemorrhoidal vein, which is very alike to humans. The vein was located through a perianal incision, dissected and ligated with a 3-0 vicryl. The skin was sutured with a 4-0 catgut thread. Animals were kept in appropriate cages and evaluated daily.


Nine days later there were hemorrhoidal piles in the anus in fifty percent (50%) of the animals. Outcome was unremarkable. There was no bleeding and all animals showed no signs of pain or suffering.


This is an affordable and reliable experimental model to induce hemorrhoids for experimental studies.

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