The Prognostic Value of Ultrasound Findings in Preoperatively Distinguishing between Uncomplicated and Complicated Types of Pediatric Acute Appendicitis Based on Correlation with Intraoperative and Histopathological Findings

Abstract

Objective: This study compares the preoperative ultrasound findings of all children with a clinical picture of acute appendicitis on the basis of intraoperative and histopathological findings to assess the feasibility of this approach in preoperatively distinguishing between uncomplicated and complicated cases.

Methods: This retrospective study includes 224 pediatric patients who underwent ultrasound prior to appendectomy at our institution between January 2016 and February 2022. Logistic regression analysis was used to investigate the association between sonographic and intraoperative histopathological findings.

Results: Of the 224 participants, 61.1% were intraoperatively diagnosed with uncomplicated appendicitis (59.8% male). Multivariate logistic regression analysis revealed that patients with a higher appendiceal diameter, presence of appendicolith, and peritonitis were more likely to suffer from complicated appendicitis. Finally, the common anatomical position of the appendix and an appendiceal diameter greater than 6 mm had the highest sensitivity (94.6% and 94.5%, respectively) for predicting complicated appendicitis, with the most specific (99.3%) sonographic finding being the existence of an abscess.

Conclusions: Preoperative abdominal ultrasound in children with a clinical diagnosis of acute appendicitis can distinguish between uncomplicated and complicated appendicitis in most cases of pediatric appendicitis. A higher appendiceal diameter, the presence of appendicolith, and peritonitis are parameters noted by ultrasound that strongly predict complicated appendicitis.

Keywords: complicated appendicitis; ultrasound; uncomplicated appendicitis.

Figure 1

Correlation between US and intraoperative/histopathological findings. (a) Normal appendix: minimal changes—mild lymphoplasmacytic infiltration in the mucosa (H&E stain, magnification ×10). (b) Acute uncomplicated appendicitis: intense presence of neutrophils (H&E stain, magnification ×10). (c) Acute complicated appendicitis without perforation: extensive inflammatory infiltration mainly composed of neutrophils and lymphocytes involving all thickness of the organ’s wall (H&E stain, magnification ×4). (d) Normal compressible appendix (note the ovoid shape because of the compression). (e) Uncompressible, with “target sign” appendix in axial view. Uncomplicated AA but with increased echogenicity of periappendiceal fat (arrow), which represents an attempt to wall-off the imminent perforation. (f) Thickening and ill-defined “target-sign” in the edematous appendix. Periappendiceal hypoechoic fluid collection (arrow) with internal echoes is present [complicated AA]. (g) Appendicolith with acoustic shadow [star-(ga)] obstructing the appendiceal lumen (diameter approximately 15 mm). Periappendiceal fat and mural hypervascularity is present [arrow in (gb)] and obliteration of wall layer structure indicates a high chance for perforation [complicated AA].