As well as Crohn’s Disease and Ulcerative Colitis, there are other conditions in which the large intestine becomes chronically inflamed, without evidence of infection. These conditions are much less common than CD and UC and some are still poorly understood. A brief review is given below.
When inflammation arises in the large bowel alone (inflammation in the small bowel is clear evidence of Crohn’s Disease) it may be sometimes difficult to tell whether it is due to Crohn’s Disease (CD) or to Ulcerative Colitis (UC) , because it has features which suggest both conditions. The distinction between the two is unclear, hence the condition’s title of ‘Indeterminate colitis’. If full evaluation of the patient including X-rays and biopsies does not allow the pathologists to decide which disease is present it is customary to treat IC in a similar way to UC, and indeed most cases of IC turn out eventually to be UC, rather than CD.
A microscopic colitis, (i.e. only seen under the microscope) caused by the formation of a collagen band (a tough and inelastic tissue) under the lining of the bowel. The main feature of the disease is watery diarrhoea.
A microscopic colitis which, under the microscope, demonstrates increased levels of lymphocytes (white cells) and is characterised by watery diarrhoea, usually without blood.
Inflammation caused by partial death of tissue (infarct) due to either a blockage in the blood supply, e.g. after major abdominal surgery or a reduced supply, e.g. poor cardiac output in heart disease. It occurs most frequently in the elderly and is characterised by violent bloody diarrhoea and abdominal pain. It can mimic CD as it is variable in extent, location and severity.
Inflammation developing from the diversion of the faecal stream following colostomy or ileostomy. Colitis may develop in the portion of the bowel which no longer has faeces passing through.
This is a rare disease causing inflammation in the blood vessels and can affect many organs in the body. When present in the bowel, it can mimic CD as it tends to occur in the ileocaecal area and segments of the colon.
Certain infections caused by various organisms can result in damage to the lining or other layers of the intestine which may mimic CD or UC. For example; Yersinia, Cytomegalovirus (CMV), Clostridium difficile or amoebiasis (in tropical countries).
It is therefore important to exclude the possibility of such an infection before making a diagnosis of Inflammatory Bowel Disease. These infections can be straight-forwardly diagnosed by examination of the stool under the microscope, or by culture of the stool to see if pathogenic bacteria are present. Your GP can send a fresh sample of stool to the laboratory for this purpose.