Haemorrhage, subdural

haemorrhoids (piles) Varicose veins in the anus, either inside the rectum (internal) or outside under the skin (external). They occur when blood pressure in the veins around the anus is too high, for example when the blood supply is trapped by excessively long retention of faeces, or when undue pressure is needed for evacuation; they often occur in patients with a sedentary life-style. Blood supply is also impeded during pregnancy and childbirth, and by high blood pressure in the portal vein (e.g. in cirrhosis of the liver), which constricts all intestinal veins. Swelling of the large intestine can also cause haemorrhoids, but often there is no identifiable cause. Small internal haemorrhoids are imperceptible and should cause no discomfort, but larger haemorrhoids can result in itching, smarting and blood in the faeces. A possible complication is prolapse, which, if it persists, can cause chronic loss of blood and anal fissure. Haemorrhoids can also become blocked or thrombosed, and cause swelling and severe pain. Inflamed, thrombosed or prolapsed haemorrhoids are directly visible on external examination, but haemorrhoids without complications can be detected only by rectoscopy, often necessary in elderly people to distinguish haemorrhoidal blood loss from loss resulting from other conditions. If haemorrhoids cause little or no discomfort surgery is not usually necessary, although a varied diet is advisable to keep faeces soft, thus avoiding the need for strain during defecation. The patient should also take exercise, and defecate regularly. Haemorrhoidal cream or suppositories suppress pain, but do not cure the condition. In the case of discomfort or complications various treatments are possible, such as sclerotherapy (injection into the vessel to seal it), cryosurgery (treatment by cold), widening the anus (dilation), or rubber-band treatment (nipping off the haemorrhoids with a rubber band). Removal by surgery (haemorrhoidec-tomy) is necessary only in 10 per cent of cases.