2.1
Haemorrhoidal tissue is a normal component of the anal canal and is composed predominantly of vascular tissue, supported by smooth muscle and connective tissue. It functions as a compressible lining that allows the anus to close completely. Internal haemorrhoids (also known as piles) are located beneath the lining of the anus and occur when the haemorrhoidal tissue of the distal rectum and anal canal prolapses. Internal haemorrhoids are usually classified according to the degree of prolapse, although this may not reflect the severity of the person's symptoms. First-degree haemorrhoids bleed but do not prolapse. Second-degree haemorrhoids prolapse on straining during bowel movements, and reduce spontaneously. Third-degree haemorrhoids prolapse on straining and require manual reduction. Fourth-degree haemorrhoids are prolapsed and cannot be manually reduced.