Does the use of computed tomography scenogram alone enable diagnosis in cases of bowel obstruction?

Background: Ileus is a pathological condition of the abdomen that presents as a medical emergency. It is characterized by potential complications such as perforation and ischemia, which can lead to significant morbidity and mortality if not promptly addressed. The successful management of ileus relies heavily on the timely and precise identification of the condition. While conventional radiography (CR) is commonly used as the primary diagnostic tool, its accuracy in identifying obstructions ranges from 46% to 80%. Furthermore, the diagnostic accuracy of identifying the location and etiology of intestinal obstruction by CR is limited, therefore making computed tomography (CT) the ideal imaging modality in this regard.

Aim: To determine the presence of acute bowel obstruction (BO) on abdominal CT scenogram images and the accuracy of determining its possible location, taking into account the experience of the observers.

Methods: A retrospective screening was conducted on an ensemble of 46 individuals who presented to the emergency department between January 2021 and January 2022 with severe abdominal pain and were subsequently monitored for suspected ileus. The abdominal CT scans of these patients were assessed by three radiologists with varying levels of experience (1, 3, and 10 years) at different intervals (1 mo apart). The evaluation focused on determining the presence or absence of BO, as well as identifying the potential location of the obstruction (small bowel or large bowel). The study employed Kappa statistics to assess inter-observer variances, while the McNamer test was used to evaluate obstruction and segmentation discrepancies between observations. A significance level of P < 0.05 was determined to indicate statistical significance.

Results: Out of the total sample size of 46 patients, 15 individuals (32.6%) were identified as female, while the remaining 31 individuals (67.4%) were identified as male. The ultimate diagnosis of 42 instances (91.3%) indicated ileus resulting from mechanical obstruction (MO). Among these patients, 14 (33%) experienced obstruction in the large bowel (LB), while 28 (66%) experienced obstruction in the small bowel (SB). The initial evaluation yielded sensitivity rates of 76.19%, 83.31%, and 83.33%, and diagnostic accuracy rates of 69.56%, 76.08%, and 80.43% for the detection of BO among the three observers. The initial study revealed that the average sensitivity of three observers in detecting the presence of ileus caused by MO was 80.94%, while the diagnostic accuracy was 75.35%. Based on the first evaluation, the senior observer demonstrated the highest sensitivity (85.71%), negative predictive value (92.60%), and diagnostic accuracy (80.43%) when accurately estimating the thick and thin segmentation, as per the final diagnosis. There was no statistically significant disparity observed in the sensitivities pertaining to the identification of ileus during the second assessment, as well as the precise determination of the segment level inside the LB or SB, when comparing the second and third observers. Nevertheless, although there was no statistically significant alteration in the detection rate of ileus by the first observer, there was a notable rise in the accuracy rate of segment estimating (73.91%). The senior assessor had a higher level of accuracy in assessing the existence of ileus and segmentation compared to the other evaluators in both evaluations.

Conclusion: The findings of our study indicate that the sensitivity and accuracy rates of abdominal CT scenogram scans in diagnosing acute MOs are similar to or greater than those of CR. Additionally, the study revealed that radiologists with more experience demonstrated a higher likelihood of accurately predicting the existence and potential localization of MO compared to their less experienced counterparts.