Haemorrhoids are enlarged cushions of blood vessels around the anal canal which, in their normal state, help control the passage of stool. Factors contributing to their development may include constipation and straining, a low-fibre diet, age, obesity, and other conditions that increase pressure within the abdomen such as pregnancy and chronic coughing. There are two main types, internal and external, described according to whether they arise in the upper or lower parts of the anal canal.
Internal haemorrhoids may descend (prolapse) and protrude through the anus. They may cause bright bleeding during or after passage of stool, mucous discharge and itchiness, or a lump if they prolapse. They are usually painless unless complicated by thrombus (clot) formation and/or strangulation, when swelling causes the tissue to be squeezed and the blood supply impaired which may result in tissue death.
External haemorrhoids may be noticed as a lump around the anus which may itch or cause discomfort. They can become painful when thrombosed.
Anal skin tags are small flaps of skin around the anus that may remain after this skin has been swollen or stretched by haemorrhoids. They may be a nuisance in maintaining hygiene.
An examination is required to assess symptoms which may be due to haemorrhoids and further investigation may be recommended to exclude other conditions.