Third-degree haemorrhoids. Close-up of external haemorrhoids (piles) around the anus. Haemorrhoids are swollen varicose veins in the lining of the anus. In severe cases such as this, the haemorrhoids protrude from the anus, and may rupture. Four veins (pink lumps) are seen, one of which is bleeding. Constipation and prolonged straining when using the toilet are through to contribute to the formation of haemorrhoids by increasing the pressure in the veins. Third- degree haemorrhoids are the most serious form of the condition, and usually require hospital treatment. They are surgically removed during a haemorrhoidectomy.