Image Quality of Abdominal Ultrasonography After Esophagogastroduodenoscopy is Preserved by Using Carbon Dioxide Insufflation

Abstract

Because bowel gas deteriorates the image quality of abdominal ultrasonography (AUS), it is common to perform AUS prior to esophagogastroduodenoscopy (EGD). This one-way order limits the availability of examination appointments. To evaluate whether EGD using insufflation of carbon dioxide (CO2), which is rapidly absorbed by the gastrointestinal mucosa, preserves the image quality of AUS performed subsequently, we designed a non-inferiority test in which each subject underwent AUS, EGD with CO2 insufflation, and a second AUS. All saved AUS moving images were randomized and evaluated using a four-point Likert scale that divides the depiction rate by 25%. Sample size was calculated to be 26 and 30 subjects were enrolled. The mean and 95% confidence interval (CI) of the image quality score at pre- and post-EGD AUS were 3.54 [3.48–3.60] and 3.46 [3.39–3.52], respectively. The difference in the means was 0.08, corresponding to a 2% depiction rate. The effect size was 0.172. The image quality of post-EGD AUS was not inferior, as demonstrated by the 97.5% CI of the difference, which did not cross the non-inferiority margin of –0.40 corresponding to depiction rate of –10%. Because EGD using CO2 insufflation does not appreciably deteriorate the image quality of AUS performed subsequently, it is permissible to perform EGD prior to AUS.