The Lack of Efficacy for Oral Contrast in the Diagnosis of Appendicitis by Computed Tomography

Abstract

Oral contrast is often used with computed tomography (CT) for the diagnosis of appendicitis. This adjunct adds time to evaluation, not all patients can tolerate enteric bolus, and the diagnostic advantages have not been well defined. Therefore, we reviewed our experience to evaluate the impact of oral contrast on diagnostic efficiency and its impact on the patient. After obtaining IRB approval, a retrospective review was conducted on patients who underwent CT with oral contrast for the indication of appendicitis over the last 4 years. Data recorded included demographics, CT results, emergency room course, operative findings, and pathology interpretation. All images were reviewed to identify presence/absence of contrast at or beyond the terminal ileum. There were 1561 patients, of whom, 652 (41.8%) were diagnosed with appendicitis and 909 (58.2%) were not (non-appendicitis). Contrast was identified at least to the level of the terminal ileum in 72.4% of the entire population. The contrast was present in 76.2% of the non-appendicitis patients and 67.0% of the appendicitis patients (P = 0.01). Mean time from oral contrast administration to CT imaging was 105.5 min, which was longer in patients with appendicitis (112.2 min) compared with non-appendicitis patients (100.9 min) (P = 0.01). Emesis of the contrast occurred in 19.3% of those with appendicitis and 12.9% of those without appendicitis (P = 0.001). Nasogastric tubes were placed in 5.8% of those with appendicitis and 5.1% of those without (P = 0.37). Appendicitis was confirmed at operation in 94.3% of those with contrast in the area and 94.4% of those without (P = 1.0). Pathology confirmed appendicitis in 90.6% of those with contrast in the area and 94.0% of those without (P = 0.17). Nearly 30% of patients receiving oral contrast for the CT diagnosis of appendicitis do not have contrast in the point of interest at the expense of emesis, nasogastric tube placement, and diagnostic delay. These detriments are amplified in patients who have appendicitis. Further, there appears to be no diagnostic compromise in those without contrast in the terminal ileum.