Comparison of colonic transit between polyethylene glycol and water as oral contrast vehicles in the CT evaluation of acute appendicitis

OBJECTIVE. The objective of our study was to assess the efficacy of a new positive oral contrast agent's ability to reach the colon during CT evaluation of acute appendicitis. SUBJECTS AND METHODS. Eighty adult emergency department patients who underwent abdominal CT to evaluate for appendicitis were studied. Forty patients received the department's standard dose of 1,600 mL of a water-iodinated contrast mixture (ratio of 2 mL of iodinated contrast material to 100 mL of water) with a standard delay time of 2-2.5 hours from the beginning of contrast medium ingestion. Forty patients were given a new oral contrast mixture of 1,000 mL of polyethylene glycol (PEG) mixed with 30 mL of iodinated contrast agent, and the examination was conducted only I hour from inception of contrast administration. Examinations were reviewed for the presence of contrast medium in the cecum and the presence of appendicitis or other abdominal abnormality. RESULTS. Thirty-eight of 40 patients in the PEG group had contrast medium in the colon at I hour after contrast administration, 20 of whom had surgically confirmed cases of appendicitis. In five other patients in that group, another cause to explain the patient's complaints was identified on imaging. Only 18 of the 40 patients who received the standard oral preparation had contrast material present in the cecum. Eleven patients in that group had confirmed appendicitis, and four others had another abnormal finding detected at CT. There was a significant difference in the success of contrast medium transit to the colon with these two agents (P < 0.0001). CONCLUSION. The use of an oral contrast agent composed of PEG and iodinated contrast material provided a marked improvement in oral agent transit to the colon even in patients with intraabdominal inflammation.