Value of ultrasound and computed tomography in the diagnosis of acute appendicitis with histopathology as gold standard

Background To evaluate the value of ultrasound (US), computed tomography (CT) and laboratory testing in diagnosing acute appendicitis and to evaluate the impact on the treatment of acute appendicitis, keeping histopathology as the gold standard. Retrospective evaluation of all patients treated surgically for appendicitis from 1 January 2016 to 31 December 2018 at Sint-Andries Hospital, Tielt, Belgium. Methods For each patient, we recorded: age, sex, duration of hospitalization, type of radiological investigation, fever (>37.3 degrees C), C-reactive protein (CRP), leukocyte particle count (LPC), Alvarado score and the type of surgery. For US and CT sensitivity, specificity and negative appendectomy rate were evaluated. Results Over a period of 3 years, 304 appendectomies were performed. The overall prevalence of appendicitis was 95.1%. Mean age was 31 years. All patients underwent radiological examination. US was performed in 35.9% (109), CT in 50.3% (153) and CT after US in 13.8% (42) of all cases. The sensitivity and specificity of CT were 99.4% and 80.0%, respectively. For US, the respective figures were 74.8 and 62.5%. CRP and LPC were significantly higher in the appendicitis group, compared to the non-appendicitis group. The negative appendectomy rate was slightly higher in the CT after US group i.e. 7.1% (3/42) compared to 4.67% (5/107) in the US group and 4.50% (7/155) in the CT group. Conclusions The diagnostic value of US and CT are both very high. The diagnostic value of clinical features and biochemistry alone is quite low. By combining radiological examination, clinical examination and laboratory values, low negative appendectomy rates can be achieved.