Specific CT Findings Can Help in Diagnosis of Perforated Versus Non-Perforated Acute Appendicitis

March 11, 2021

By Erika Powers

CLEVELAND, Ohio -- March 10, 2021 -- Certain preoperative CT findings can be helpful in predicting appendiceal perforation, according to a study presented at the Virtual 2021 European Congress of Radiology (ECR).

“Acute appendicitis is the most common cause for acute abdominal pain requiring surgery and perforation is reported in 13% to 20% of patients,” said Tzu-Yun Chung, MD, Gosford Private Hospital, Gosford, Australia, and colleagues. “Preoperative imaging is important in reducing negative appendicectomy rates and predicting prognosis; however, the classic CT findings of abscess and extraluminal air are not always present in patients with perforated appendicitis, especially in early stages.”

The current study included 134 patients who underwent an appendectomy from August 2017 to August 2018. A CT was performed on all patients before surgery, and most (94.8%) received intravenous contrast. Of the patients, 41 (31%) had a final diagnosis of perforated appendicitis; 93 (69%) had non-perforated appendicitis.

There was no statistical significance between the 2 groups in terms of age, sex, body temperature at triage, or white cell count on admission. However, the duration of abdominal pain from onset to presentation was statistically (P

The appendix diameter was 11.8 mm (±2.8; range, 6-20 mm) in the non-perforated group and 13.4 mm (±2.9; range, 6-21 mm) in the perforated group (P

In the CT reports, 15 (11%) had been reported as perforated appendicitis, while 117 (87%) had been reported as non-perforated appendicitis.

Abscess and extraluminal gas were 100% specific for appendiceal perforation, but had low sensitivity (7% and 27%, respectively). Phlegmon had a specificity of 84% and a sensitivity of 61%, focal appendiceal wall defect had a specificity of 87% and a sensitivity of 56%, and free fluid had a specificity of 60% and a sensitivity of 80%.

Periappendiceal fat stranding and appendiceal diameter >10 mm were 100% and 93% sensitive, respectively, but each had low specificity in predicting perforation (9% and 17%, respectively).

Presence of an appendicolith had a sensitivity of 51% and a specificity of 50%, and was considered not useful in predicting appendiceal perforation.

Phlegmon had the greatest diagnostic accuracy (area under the curve [AUC] = 0.722), followed by focal wall defect (AUC = 0.719), and free fluid (AUC = 0.703).

“Presence of abscess or free gas is highly specific for perforation,” said Dr. Chung. “Focal appendiceal wall enhancement defect, phlegmon, and free fluid may be helpful when assessed together, although individually, had low sensitivity.”

The authors noted that preoperative CT scans were reviewed on 3-mm thick slice imaging, which may have reduced the detection rate of a focal wall enhancement defect in the study.

[Presentation title: Computed Tomography in the Diagnosis of Perforated Versus Non-Perforated Acute Appendicitis. Poster C-10097]