Although a very common abnormality, its prevalence probably is underestimated because of the many asymptomatic patients. Symptoms present as nonspecific, indicating that a directed history and a thorough examination, including an anoscopy when necessary, are essential in guiding the physician to the appropriate diagnosis and management. The usual course is acute, chronic, or relapsing. Internal, external, and mixed hemorrhoids are differentiated by their anatomical origin in the anal canal. Mixed hemorrhoids are confluent internal and external hemorrhoids.
External hemorrhoids drain into the inferior rectal vein, which drains into the inferior vena cava.
Anastomoses exist between these 2 veins and the middle rectal vein. Hemorrhoids are dilated arteriovenous complexes. Although many theories exist regarding the unclear pathophysiology of hemorrhoids, the vascular cushion theory has the most acceptance. These vascular cushions, found at the anorectal junction above the dentate line, are anatomically normal. The vascular cushions are present in adults, in children, and even in the embryo.