Diagnostic pathways in acute appendicitis: Clinical score plus ultrasound outperform CT scan or upfront surgery, especially in doubtful cases.

Background: Controversies remain on the diagnostic strategy in suspected AA, considering the different settings worldwide.

Material And Methods: A prospective observational international multicentric study including patients operated for suspected AA with a definitive histopathological analysis was conducted. Three groups were analyzed: (1) No radiology; (2) Ultrasound, and (3) Computed tomography. The aim was to analyze the performance of three diagnostic schemes.

Results: Three thousand and one hundred twenty three patients were enrolled; 899 in the no radiology group, 1490 in the US group, and 734 in the CT group. The sex ratio was in favor of males (p < 0.001). The mean age was lower in the no radiology group (24 years) compared to 28 and 38 years in US and CT-scan groups, respectively (p < 0.001). Overall, the negative appendectomy rate 3.8%: no radiology group (5.1%) versus US (2.9%) and CT-scan (4.1%) (p < 0.001). The sensitivity and specificity analysis showed the best balance in clinical evaluation + score + US. These data reach the best results in those patients with an equivocal Alvarado score (4-6). Inverse probability weighting (IPW), showed as the use of ultrasound, is significantly associated with an increased probability of formulating the correct diagnosis (p 0.004). In the case of a CT scan, this association appears weaker (p 0.08).

Conclusion: The association of clinical scores and ultrasound seems the best strategy to reach a correct preoperative diagnosis in patients with clinical suspicion of AA, even in those population subgroups where the clinical score may have an equivocal result. This strategy can be especially useful in low-resource settings worldwide. CT-scan association may improve the detection of patients who may potentially be submitted to conservative treatment.