[Etiopathogenesis and physiopathology of hemorrhoidal disease]

Many possible causes have been proposed to explain the pathogenesis of symptomatic hemorrhoids: constipation and abnormal bowel habits are commonly blamed despite largely contrary evidence. The most consistently demonstrated physiological abnormality is an increased maximum resting anal pressure. The pathophysiologic theory, made popular by Thomson's studies, in which the anal cushions break their elastic support and become more sensitive to the increase of pressure from straining and to trauma from hard stool, with a progressive downward displacement, is currently the best accepted. The intimate mechanism of functioning and control of the arteriovenous anastomoses remains unclear as does the existence of an individual susceptibility in which a part is played by socioeconomic, cultural and psychological factors.