[Efficiency of ultrasonography in the diagnosis of acute appendicitis]

Importance of the problem. Atypical or precocious presentation of acute appendicitis in children causes false diagnosis.

To determine internal and external validity of ultrasonography for confirmation diagnosis of acute appendicitis.

Patients with suspicious acute appendicitis treated in 1998. They have been classified into two groups. Group 1: patients with appendicitis; Group 2: patients with non-specific abdominal pain.

Ultrasonography equipment (5 and 7.5 MHz).

Ultrasonography has been considered as positive when 3 or more of the typical signs of appendicitis have been detected. Analysis unit: positivity of the test and presence or absence of illness confirmed by histologic analysis of the appendix obtained through laparotomy.

Number of patients selected for the work: 139. Middle age: 8 years-old (range: 2 to 14 years); 75% were males, 25% females. Patients included in group 1: 42; patients included in group 2:97. False positive rate was 12.23%, while false negative rate was 7.19%. Sensibility was 76%, specificity was 82%, positive predictive value was 65%, negative predictive value was 88% and precision was 80%. Odds-ratio pre-test: 0.43; Odds-ratio post-test: 0.64.

Probability of accuracy diagnosis is duplicated by ultrasonography. Liability of the test is diminished by variability due to observer.