Definition

Lower GI bleeding is defined as bleeding distal to the ligament of Treitz (i.e. some of the small bowel, the colon and the rectum) which presents with the passage of bright red blood per rectum (haemotochezia) without the presence of blood in gastric aspirate.

Acute lower GI bleeding is of recent onset and may be severe, resulting in haemodynamic instability and decreasing haemoglobin levels. The diagnosis is often difficult to make and may require multiple investigations to identify the source of bleeding.