ABC of colorectal diseases. Anal fissures and fistulas.

B D HancockAnal fissures most commonly affect patients aged between 30 and 50.They are equally common in men and women.A fissure is a split in the lower half of the anal canal extending from the anal verge towards the dentate line.Most fissures are posterior, but anterior ones are often seen in women.The cause is not clear, but a fissure often starts after an attack of either diarrhoea or constipation.