Anatomy, Physiology and Pathophysiology of Haemorrhoids

Haemorrhoidal Disease (HD) is a frequent anal disorder and one of the most common findings identified at the colorectal clinic. This article aims to provide an overview of the anatomy, physiology and pathophysiology of haemorrhoids and haemorrhoidal disease.Internal haemorrhoids are vascular cushions located in the anal canal, above the dentate line and covered by columnar epithelium. They contribute to the faecal continence and the sensitivity of the anal canal. The enlargement and/or sliding of haemorrhoidal tissue produce symptoms and complications, the so-called haemorrhoidal disease.A systematic research was realized, looking at the best evidence in literature, searching PubMed, Embase, Cochrane library and the most renowed textbooks of colorectal surgery from January 1980 to January 2020.Aetiology and pathophysiology of HD are still controversial, but multifactorial. Disruption of stromal scaffolding, enlargement of vascular component, elevated anal pressure and rectal redundancy represent key events in the development and complications of the disease. Local inflammation may also play a role. Goligher's classification remains the most widely used. Thorough patient history and examination are paramount to diagnose HD, excluding other anal or colonic pathologies.Several aspects of etiopathogenesis and pathophysiology remain controversial. Further studies are needed to obtain a better understanding of the disease.