Bloody stool

A bloody stool, when described by a patient, can mean a variety of things which must be distinguished by careful questioning. The important features are:

• whether or not the blood is changed, as in melaena, or unchanged, frank bleeding. The conventional wisdom is that the further up the GI tract the bleed occurs, the more changed the blood will be. However, it is possible to have a frank bleed from, for example, a perforated duodenal ulcer
• the timing of the bleed with respect to the passage of stool. For example, bleeding after passage may be from haemorrhoids.
• the mixing of blood with stool. Mixed blood and stool implies a bleed at the level of the caecum to transverse colon; blood around the stool implies that the bleeding is from the sigmoid colon or rectum