Diagnostic accuracy of low dose CT-Scan abdomen in patients with clinical features of acute appendicitis.

Background & objective: Acute appendicitis is one of the commonest causes of acute abdominal pain presenting to emergency department (ED) and Computerized Tomography scan (CT) is considered gold standard for its diagnosis. Internationally Low Dose Computerized Tomography scan (LDCT) in emergency department is recommended as a beneficial tool to diagnose acute appendicitis with less exposure to radiation and reduction in the rate of negative laparotomy. Local trials are needed to determine the diagnostic accuracy of LDCT as the first line imaging test for acute appendicitis. Our objective was to determine the diagnostic accuracy of LDCT as the first line imaging test for acute appendicitis.

Methods: An observational study was conducted over a sample of 147 patients presented with suspected acute appendicitis to the emergency department of Ziauddin University Hospital, Karachi from November 2018 till May 2019. Non-probability consecutive technique used. Aged ≥ 16 years presented in emergency department with the history (symptoms) and physical examination (Signs) suspecting acute appendicitis were included. Patients with contraindications to CT scan e.g. pregnant women. Patients with signs of Acute Peritonitis requiring immediate surgery. CT scan refused by the patient or patient's attendant were excluded. Histopathology was the gold standard in diagnosing acute appendicitis. The data was analyzed using open epi sample size calculator.

Results: One hundred forty six patients had positive findings on LDCT for acute appendicitis (99.3%) whereas only one patient had negative findings (0.7%). The sensitivity and specificity of LDCT for the detection of acute appendicitis were estimated as 96.45% and 16.67% by taking histopathology as gold standard. Negative predictive value (NPV) and positive predictive value (PPV) were estimated as 16.67% and 96.45% respectively. The overall accuracy of LDCT was 93.88%.

Conclusion: Our study showed that for diagnosing acute appendicitis, LDCT is harmless, fast and economical imaging modality and has diagnostic accuracy with decrease in radiation dose.