Thickening of bowel on X-ray is an infrequent but important finding. On X-ray, you will actually see thickening of the bowel folds in the small bowel or colon. This is described as thumb printing in the colon where you scattered areas of thumb imprint like thickening projecting into the colon.
The general categories of abnormality may include edema or fluid underneath the surface or mucosa of the bowel, bleeding or cancer spread in the bowel wall. The underlying causes are multiple, but sometimes the underlying history will help as well as further imaging with a CT scan.
Bowel thickening from edema or fluid can be from infection as in pseudomembranous colitis which can occur in sick hospitalized patients from an infection of the colon. Often antibiotic or chemotherapy use precedes the infection. Other forms of colitis or colon inflammation can be from Crohn’s disease or ulcerative colitis.
Bowel wall thickening can also occur from ischemia or when the bowel is starved of blood flow. The bowel can also become thickened after therapy for cancer such as radiation. After trauma, the bowel can become thickened from bleeding into the wall. This can also occur when a patient is on blood thinners.
Bowel cancer can cause a smaller area of thickening. This is rarely detected in X-rays. A colon cancer or lymphoma will have bowel wall thickening. Cancer spread to the bowel wall also have thickening. Cancer involving the bowel wall can also cause an obstruction which is more likely to be discovered on X-ray. One mimicker of bowel wall thickening is when the bowel is collapsed. This is more of an issue on CT scans.
When bowel wall thickening is identified on X-ray, often the clinical context will determine the most likely diagnosis. For example, a sick hospitalized patient on antibiotics will most likely have infectious colitis. A patient with chronic diarrhea and abdominal pain may have inflammatory colitis or Crohn’s disease. Rarely will the exact cause of the bowel wall thickening be identified on X-ray. In fact, most cases of bowel wall thickening will not be seen on X-ray.
In most cases, a CT scan will be ordered. This will allow a closer look at the bowel and any associated abnormalities and the extent of abnormality. For example, a blocked artery may lead to a diagnosis of ischemic colitis. A mass or lymph nodes may lead to a diagnosis of cancer. Often a specialist gastroenterologist may be consulted for additional support.