The diagnostic value of indirect ultrasound signs during acute adult appendicitis

PurposeTo evaluate the diagnostic value of indirect ultrasound signs during acute appendicitis.Patients and methodsOur retrospective study lasted 5 years, from May 2005 to April 2010. It concerned 620 cases of appendectomy performed following prior ultrasound examination of the right iliac fossa (RIF). In 448 cases, ultrasonography clearly showed the appendix, which was inflamed. The presence of indirect signs of appendix inflammation without visualisation of the appendix was confirmed by ultrasound examination in 160 cases. In 12 cases, the appendix was not visualised nor were there any indirect signs on the ultrasound image. The indirect signs involved were hypertrophy of the peritoneal fat (HPF), pain caused by compression on exploration of the right iliac fossa, and localised hypokinesia in the digestive loops (LHL). We compared the results found by ultrasonography with the operative and anatomical pathology reports.ResultsThe positive predictive value of the indirect signs of appendicitis on the ultrasound scan was 95.8% if the three indirect signs were associated, 87.5% for the association of pain and HPF, 45.8% for the association of pain and LHL, and 25% if there was just pain. The negative predictive value of the indirect signs of appendicitis on the ultrasound scan was 57.2% if the three signs were associated, 65.9% for the association of pain and HPF and 60.7% for the association of pain and LHL, with 83.3% for pain alone. The sensitivity of the indirect signs was 83.9% if the three signs were associated, 31.8% for the association of pain and HPF, 50% for the association of pain and LHL, and 50% if there was just pain. The specificity of the indirect signs was 85.7% if the three signs were associated, 96.7% for the association of pain and HPF, 56.7% for the association of pain and LHL, and 62.5% if there was just pain.ConclusionWhen tomodensitometry cannot be performed and the appendix is not visible on ultrasound examination, indirect ultrasound signs must be systematically sought, particularly in populations in which appendicitis are highly prevalent.