They include: a)       Acute- sudden, severe bleeding is seen. b)       Chronic- the GI bleed persists over a long period (on and off). c)       Occult bleeding is not evident since it is microscopic. The signs of blood loss can be revealed only through laboratory investigations. d)       Overt-visible signs of GI bleed are seen, which include blood in vomit and black tarry stools (melena). e)       Obscure- when standard endoscopy procedure does not reveal a source of GI bleeding.