Some causes of chronic blood loss are complications of peptic ulcer and inflammatory bowel diseases such as Crohn's disease or ulcerative colitis, according to WebMD and the Crohn's & Colitis Foundation of America. Extremely heavy menstrual bleeding, or menorrhagia is also a cause of chronic blood loss, according to Mayo Clinic.
The complications of a peptic ulcer in the stomach lining, the esophagus or the small intestine can be slow bleeding that causes the patient to become anemic or a rapid blood loss that necessitates a blood transfusion, according to Mayo Clinic. The patient passes black or bloody stool or throws up black or bloody vomit.
Inflammatory bowel diseases occur when ulcers invade the intestines, says WebMD. Sometimes, inflammatory bowel diseases are the result of a person's own immune system attacking the bowel, but other cases are caused by viruses or bacteria. The two major forms, Crohn's disease and ulcerative colitis, are different because of where the disease attacks. In Crohn's disease, the disorder usually affects the first part of the colon and the last part of the patient's small intestine. Ulcerative colitis only strikes the colon, claims the Crohn's & Colitis Foundation of America. In both conditions, the patient passes bloody stool.
Though even normal menstruation is a cause of chronic blood loss, menorrhagia happens when menstrual periods become extremely heavy and prolonged, says Mayo Clinic.