The role of CT in decision for acute appendicitis treatment

Abstract

PURPOSE Acute appendicitis is the most common cause of the acute abdomen requiring surgery. Although standard treatment has been surgery, it has been seen in recent years that treatment is possible with antibiotics and non-operative observation. In this study, our aim is to determine whether the CT findings in patients diagnosed with acute appendicitis can be used for directing treatment. METHODS A retrospective analysis was conducted on 138 patients with acute appendicitis who underwent CT between 2015 - 2019. In this study, medical treatment group (n = 60) versus surgical treatment group (n = 78) and successful antibiotic treatment group (n = 23) versus unsuccessful antibiotic treatment group (n = 14) were compared. Appendiceal wall thickness, appendiceal diameter, the severity of mural enhancement, intra-abdominal free fluid, the severity of periappendiceal fat stranding, size of pericecal lymph node, appendicolith, adjacent organ findings and the CT appendicitis score of groups were compared with Pearson Chi-square and Mann Whitney U tests. Multivariable logistic regression was used to identify predictors of surgical treatment, expressed as odds ratios (ORs) with 95% confidence intervals. Diagnostic efficacies of appendiceal diameter, the CT appendicitis score and developed model were quantified by ROC curves. RESULTS Appendiceal diameter (P < .001), adjacent organ findings (P = .041), the CT appendicitis score (P < .001), the severity of periappendiceal fat stranding (P = .002), appendicolith (P = .001) and intra-abdominal free fluid (P <0.001) showed statistically significant differences between the medical and surgical treatment groups. According to the logistic regression test, if the patients with appendiceal diameter ≥13mm (OR = 5.1, 95%CI 1.58 - 16.50), appendicolith (OR = 4, 95%CI 1.17 - 13.63) and intra-abdominal free fluid (OR = 3.04, 95%CI 1.28 - 7.20), surgeons should prefer surgical treatment. The AUCs for the CT appendicitis score, the appendiceal diameter and the model were 0.742 (95% CI 0,659 - 0,824), 0.699 (95% CI 0.613 - 0.786) and 0.745 (95% CI 0.671 - 0.819), respectively. As the successful and unsuccessful medical treatment groups were compared, the only significant parameter was the severity of mural enhancement (P = .005). CONCLUSION CT findings may be helpful in patients with uncomplicated acute appendicitis whose treatment surgeons are indecisive about. We can recommend surgical treatment in cases with appendix diameter ≥13mm, intraabdominal free fluid, appendicolith, high CT appendicitis score and severe mural enhancement.

Figure 1.

Derivation of the study population. CT, computed tomography.

Figure 2.

Example of the severity of mural enhancement. On contrast-enhanced abdominal CT scans, if the severity of mural enhancement (thick arrow) was less pronounced (a) than the right external iliac artery (fine arrow), it was graded as 1. If the severity of mural enhancement (thick arrow) was equal or more pronounced (b) than the right external iliac artery (fine arrow), it was graded as 2. CT, computed tomography.

Figure 3.

Example of the wall thickness of the appendix. On contrast-enhanced abdominal CT scans, it was graded as 0 while the wall thickness of the appendix was below 3 mm (a) and 1 if 3 mm or above (b).

Figure 4.

Example of the appendix diameter. On contrast-enhanced abdominal CT scans, the diameter of the appendix lumen was measured and it was graded as 1 (≤9 mm) (a), 2 (10-12 mm) (b), and 3 (≥13 mm) (c).

Figure 5.

Example of the severity of periappendiceal fat stranding. On contrast-enhanced abdominal CT, the severity of periappendiceal fat stranding was graded as 0 (none) (a), 1 (mild) (b), and 2 (severe) (c).

Figure 6.

Box and whisker plots show the distribution of the appendix diameter (a) and the CT appendicitis score (b) in surgical and medical treatment groups.

Figure 7.

ROC analysis of appendiceal diameter, appendicitis score 1 (comparison of medical treatment and surgical treatment groups), model, and appendicitis score 2 (comparison of successful and unsuccessful medical treatment groups). ROC, receiver operating characteristic curve.