Relative value of clinical, laboratory and imaging tools in diagnosing pediatric acute appendicitis

Aim of the study was to evaluate the relative value of the tools used to diagnose suspected acute appendicitis (AA) in children.

A retrospective review of data from 1 848 children admitted to the Pediatric Surgery Department between 2004 and 2008 in our university-affiliated medical center was conducted. A total of 780 children underwent appendectomy at first presentation. Of these patients, 75 children required removal of their appendix during laparotomy for other reasons and 19 had appendectomy following peri-appendicular abscess and were excluded from the study. The study included 686 children (2-16 years of age) with presumed AA managed by appendectomy. Clinical, laboratory, and imaging data were collected and compared to pathology results.

Of the 686 children who underwent surgery for suspected AA, 34 (5%) had a normal appendix (negative appendectomy rate). No statistical differences were found between normal and AA groups with regard to vomiting, diarrhea, pain duration, and peritoneal signs on admission. Children in the AA group were younger (10.9±3.2 vs. 12.1±2.3 years, p=0.004), had higher fever (36.9±0.7°C vs. 37.4±0.8°C, p=0.004), WBC (14.8±4.8 vs. 10.5±4.6×103/mL, p<0.0005), and neutrophil counts (77.2±11.1% vs. 64.0±15.9%, p<0.0005) on admission, and larger appendicular diameters on ultrasound (US) examination (0.9±0.2 cm vs. 0.7±0.08 cm, p<0.0005). The parameters with the highest positive predictive values for AA were WBC (>10×10 (3)/mL), neutrophil (>66%) count on admission (positive predictive value [PPV]=0.971 and 0.975, respectively), and appendicular diameter on US (>6 mm; PPV=0.968). These 3 parameters combined had a PPV of 0.991.

The results of laboratory tests (WBC, neutrophils) and imaging (US) contributed far more than clinical signs and symptoms (pain duration, vomiting, diarrhea, fever, and peritoneal signs at first physical examination) to the correct diagnosis of AA in children. When these 3 parameters were positive, the probability of a false positive (normal appendix) was only 1%. The contribution of US was particularly high as it was used primarily in patients in whom the diagnosis was in doubt and its results matched the final diagnosis better than diagnoses based on clinical signs and symptoms alone. It provides the additional benefit of no radiation exposure.