Evaluation of Role of Periappendiceal Fat Echo Sign on Ultrasound in Cases of Acute Appendicitis Keeping CT as Gold Standard

Naila Rehman; Syed Muhammad Shahnawaz Hyder

doi:10.70749/ijbr.v3i3.2411

Authors

Naila Rehman Department of Radiology, Indus Hospital & Health Network, Karachi, Sindh, Pakistan.
Syed Muhammad Shahnawaz Hyder Department of Radiology, Indus Hospital & Health Network, Karachi, Sindh, Pakistan.

DOI:

https://doi.org/10.70749/ijbr.v3i3.2411

Keywords:

Acute Appendicitis, Ultrasonography, Periappendiceal Fat Echo Sign, Computed Tomography, Diagnostic Accuracy.

Abstract

Background: Acute appendicitis is a global surgical emergency, with a significant burden in resource-constrained countries like Pakistan. While computed tomography (CT) is the diagnostic gold standard, its limitations like ionizing radiation, cost, and limited availability, make ultrasonography (USG) the pragmatic first-line imaging tool. However, USG's variable accuracy necessitates reliable secondary signs. The Periappendiceal Fat Echo Sign (PFES), a hyperechoic halo representing inflamed mesenteric fat, shows promise in improving sonographic diagnosis. Aim of this study is to evaluate the diagnostic accuracy of the PFES on ultrasound for detecting acute appendicitis, using contrast-enhanced CT as the gold standard. Methods: This cross-sectional study was conducted at Fazaia Postgraduate Medical Institute, Islamabad, from September 2023 to March 2024. A total of 164 consecutive patients (mean age 33.91 ± 10.04 years; 53.7% female) with clinical suspicion of acute appendicitis underwent graded compression ultrasonography followed by CT. A positive PFES was defined as hyperechogenicity of the periappendiceal fat. Diagnostic accuracy parameters (sensitivity, specificity, PPV, NPV, overall accuracy) were calculated against CT findings. Results: CT confirmed acute appendicitis in 120 patients (73.2%). Ultrasound utilizing PFES demonstrated a sensitivity of 91.7%, a specificity of 75.0%, a positive predictive value of 90.9%, a negative predictive value of 76.7%, and an overall diagnostic accuracy of 87.2%. Stratified analysis revealed superior performance in male patients (specificity 80.0% vs. 70.8%) and notably higher accuracy in obese patients (91.6%) compared to other BMI groups. Conclusion: The Periappendiceal Fat Echo Sign is a highly sensitive and valuable sonographic marker for acute appendicitis. Its incorporation into standard ultrasound protocols can significantly enhance diagnostic confidence, particularly in settings where CT access is limited. By facilitating accurate and early diagnosis, PFES can help reduce negative appendectomy rates and optimize the use of advanced imaging, ultimately improving patient outcomes.

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