Sebastian Bickelhaupt, Presenter: Nothing to Disclose

Sandra Tschirky, Abstract Co-Author: Nothing to Disclose

Michael A. Patak MD, Abstract Co-Author: Nothing to Disclose

The clinical diagnosis of acute appendicitis in emergency departments is often backed by ultrasound (US) or/and computed tomography (CT). US is commonly the initial modality as an inexpensive and fast tool avoiding ionizing radiation. The increasing number of patients with a high body mass index (BMI) might limit the use of US. Our study investigated the accuracy of US for the diagnosis of appendicitis correlated to the patients BMI, the severity of inflammation and the need for additional CT-examinations.  

716 patients with suspected acute appendicitis(mean age 40.33, 309 female, 408 male)were included in this IRB-approved, retrospective study between 2005-2011. Inclusion criteria:clinically suspected acute appendicitis, data of body mass index(BMI),leukocytes,c-reactive protein and a consecutive surgical intervention with histopathologically proven appendicitis. Patients grouping followed WHO definitions(BMI<18.5;18.5-24.9;25.0-29.9;>30).Correlations between the BMI, ultrasound-ability in detecting acute appendicitis, the necessity for CT examinations(Siemens Somatom 64, Erlangen, Germany) and the level of inflammation were calculated using Spearmans-rank-correlation. .

Ultrasound-usage decreased with increasing BMI from 65.5%(BMI<18.5)and 67.11%(18.5-24.9) to 54.6%(25.0-29.9) and 45.6%(>30) in a significant negative correlation(r=-0.1,p=0.006). Vice versa initial CT usage increased from 7.82% to 18.5% (r=0.2,p<0.05). The need for additional CT after US significantly correlated with the BMI(r=0.1,p=0.005) (3.4%;10.7%;11.6%;26.5%). The diagnostic certainty of ultrasound significantly decreased with increasing BMI from 48.27% and 45.8% to 38% and 30.8% (r=-0.097,p=0.006), that did not correlate with levels of inflammatory markers(p>0.05) which did not differ between the groups.

The diagnostic certainty for the diagnosis of acute appendicitis significantly correlates with the BMI of the patients, leading to an increasing need for additional CT in obese patients. This finding was independent of the severity of inflammation with no correlation between the level of inflammatory markers and the diagnostic certainty of the ultrasound examination.

Our study revealed a significant and robust negative correlation between the diagnostic certainty and an increasing BMI in the patients which helps to assess the appropriateness of initial ultrasound in patients depening on the BMI.

Bickelhaupt, S, Tschirky, S, Patak, M, Usability of Ultrasound for the Diagnosis of Acute Appendicitis Correlated to Patients BMI and the Severity of Inflammation.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14007390.html