What is the role of Air Contrast Barium Enema (ACBE) when colonoscopy is not feasible?

From the Guidelines

Air Contrast Barium Enema (ACBE) is no longer the preferred diagnostic tool when colonoscopy is not feasible, as CT colonography has shown superior sensitivity and ability to detect extracolonic abnormalities 1. When colonoscopy cannot be performed due to technical difficulties, patient contraindications, or incomplete colonoscopy, alternative diagnostic tools are considered. ACBE involves introducing barium sulfate suspension and air into the colon to create contrast for X-ray imaging, allowing visualization of the colonic mucosa and detection of polyps, tumors, diverticula, and inflammatory changes. Key points to consider:

• The procedure typically requires thorough bowel preparation with clear liquids for 24 hours, laxatives like polyethylene glycol, and sometimes bisacodyl tablets.
• During the procedure, a thin tube is inserted into the rectum, barium is introduced, followed by air insufflation, while multiple X-ray images are taken from different angles.
• Though less sensitive than colonoscopy for detecting small polyps (less than 1 cm) and flat lesions, ACBE can still identify significant structural abnormalities and is particularly useful for patients who cannot tolerate sedation, have severe comorbidities, or have anatomical challenges like tortuous colons or obstructive lesions. However, given the availability of CT colonography, ACBE is now mainly considered when CT colonography is not feasible or available 1.

From the Research

Role of Air Contrast Barium Enema (ACBE) when Colonoscopy is not Feasible

• ACBE can be used as an alternative diagnostic tool when colonoscopy is not feasible, as it is less expensive and invasive than colonoscopy 2.
• However, ACBE has been shown to be less sensitive and specific than colonoscopy, particularly for detecting small polypoid lesions 2, 3.
• The sensitivity of ACBE for detecting lesions 10 mm or larger in size has been reported to be around 48% 3, while colonoscopy has a sensitivity of 98% for detecting lesions of the same size 3.

Limitations of ACBE

• ACBE has been shown to have poor sensitivity for detecting polypoid lesions or adenomas, especially in the presence of diverticula 2.
• The reliability of ACBE after incomplete colonoscopy has been reported to be less than previously thought, with only 77% of studies being technically adequate 4.
• ACBE is not recommended in suspected small-bowel obstruction, but should be performed in all cases of large-bowel obstruction, except when perforation is a possibility or when the cecum measures 10 cm or larger in diameter 5.

Comparison with Colonoscopy

• Colonoscopy has been shown to be more sensitive than ACBE for detecting colonic polyps and cancers, with a sensitivity of 98% for lesions 10 mm or larger in size 3.
• Colonoscopy also has the advantage of being therapeutic as well as diagnostic, and can guide the surgeon in doing proper resections based on tissue diagnoses 6.
• However, colonoscopy is not always feasible, and ACBE can be used as an alternative diagnostic tool in such cases.