Finding the right tests…
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Finding the right tests…
X-Ray
A double contrast barium enema uses two agents together rather than one: barium is run into the colon and then largely drained out, leaving a thin coating on the bowel wall, and air is then added to expand the colon around that coating. The combination outlines the lining in finer detail than barium alone, since the thin barium film against an air-filled colon shows the surface of the wall rather than just its outer shape. One published audit of this technique found it detected colorectal cancer with a sensitivity around 96%, missing a small minority of cases, a level that supported its past use in cancer screening before colonoscopy became more widely available.
The images show the colon's inner surface in detail, since the thin barium coating against the air-filled colon highlights small polyps, subtle lining changes, and diverticula that a fuller barium fill can obscure. The radiologist compares this surface detail against the overall shape and width of the colon.
This study builds on a standard barium enema by adding a second contrast agent, air, after most of the barium has drained back out, leaving only a thin coating on the colon wall.
A colon fully filled with barium shows its outer shape well but can hide small surface details. Once most of the barium is drained and air takes its place, the thin barium film left behind clings to the lining and shows up clearly against the air-filled space around it, which is why this technique is better suited to spotting small polyps or subtle changes in the bowel wall.
A published audit of this specific technique reported it detected colorectal cancer with a sensitivity around 96 percent in the cases reviewed, a level that once supported its use for cancer screening. Colonoscopy and CT colonography are more commonly used for that purpose today, but a double contrast study can still answer the same structural questions when those are not the right fit.
It means two contrast agents are used together: barium, which is mostly drained out after coating the colon wall, and air, which is added afterward to expand the colon around that thin coating. This combination shows the lining in more detail than barium alone.
It is generally considered better at showing small polyps and subtle lining changes, since the thin barium coating against air shows surface detail that a fully barium-filled colon can hide. Your doctor decides which version fits what they are checking for.
One published audit found this technique detected colorectal cancer with a sensitivity around 96 percent among the cases studied. Your doctor can explain what this means for your specific situation.
This page is general information about the test, not medical advice. Your own report's reference ranges apply — please discuss your results with your doctor.
You may feel some cramping or bloating as the colon expands with air. Tell the technologist if the discomfort feels significant at any point.
Colonoscopy and CT colonography are used more often for screening now, partly because a polyp found during colonoscopy can be removed in the same visit. This test still has a role when those options are not suitable.
A clear colon is important for this test to work well, but exact preparation steps vary by centre. Ask your doctor or the centre directly what they need you to do.
It generally involves an extra step of draining the barium before adding air, so the appointment can take a bit longer. Ask the centre what to expect for your visit.