Gangrene of the appendix is mainly due to the accumulation of pus in the appendiceal lumen caused by acute inflammation of the appendix, which leads to increased pressure in the lumen and obstruction of blood circulation in the appendiceal wall, eventually leading to necrosis of the appendiceal wall and gangrene. Gangrenous appendicitis is a severe form of appendicitis and immediate medical attention should be sought to avoid delay.