CT rectal contrast is used to clearly visualize the

 CT rectal contrast is used to clearly visualize the rectum, colon, and surrounding pelvic structures during a CT scan. It improves diagnostic accuracy for detecting abnormalities such as fistulas, abscesses, bowel perforations, or postoperative leaks.

Why CT Rectal Contrast is Done

CT rectal contrast enhances the visualization of the large intestine and helps the radiologist detect issues like rectal or sigmoid carcinoma, diverticulitis, perirectal abscesses, and anastomotic leaks after surgery. It increases the sensitivity and specificity of CT imaging, helping avoid missed diagnoses.​

How the Procedure is Done

During the procedure, a soft flexible catheter is gently inserted into the rectum while the patient lies on their side. A warmed, diluted contrast material (usually iodine-based or barium sulfate) is then slowly instilled into the rectum via syringe or enema. The process fills the lower bowel, making its walls visible on CT images. Patients are usually asked to hold the contrast during scanning to get optimal imaging. The procedure typically takes 10–15 minutes.​

What Patients Feel During the Procedure

Most patients experience a mild feeling of fullness, bloating, or slight discomfort due to the contrast and air distending the bowel. Some describe it as similar to the sensation before passing gas. This feeling subsides once the contrast is drained after the scan. The experience is usually well tolerated, and patients can resume normal activities immediately afterward.​

Possible Side Effects

The side effects depend on the type of contrast used:

• Barium-based contrast may cause temporary stomach cramps, bloating, constipation, or nausea.​

• Iodine-based contrast may cause mild itching, warmth, or nausea; severe allergic reactions are very rare.​

• Most studies have shown no serious adverse effects from rectal contrast when performed properly.​

Patients with bowel perforations, severe dehydration, or allergy to iodine should inform their doctor in advance, as alternative techniques or preparations may be required.​

Summary for Your Radiography Blog (“Radiographic Gyan”)

In simple terms, CT rectal contrast helps doctors get a clearer picture of the intestines and rectum — especially for disease detection or post-surgical assessments. The procedure involves inserting a small tube in the rectum and filling it with contrast, which can make patients feel full or bloated for a few minutes. Side effects are rare and usually mild, making it a safe and valuable diagnostic tool in radiology practice.