Three-step sequential positioning algorithm during sonographic evaluation for appendicitis increases appendiceal visualization rate and reduces CT use

• Published in: American journal of roentgenology (1976) Vol. 203; no. 5; pp. 1006 - 1012
• Main Authors: Chang, Stephanie T, Jeffrey, R Brooke, Olcott, Eric W
• Format: Journal Article
• Language: English
• Published: United States 01.11.2014
• Subjects: Adolescent; Aged; Aged, 80 and over; Algorithms; Appendicitis - diagnosis; Child; Child, Preschool; Data Compression - methods; Data Compression - standards; Female; Humans; Image Enhancement - methods; Infant; Male; Middle Aged; Observer Variation; Patient Positioning - methods; Patient Positioning - statistics & numerical data; Reproducibility of Results; Retrospective Studies; Sensitivity and Specificity; Tomography, X-Ray Computed - utilization; Ultrasonography - methods; Ultrasonography - statistics & numerical data; Young Adult; spiral CT; radiation protection; appendicitis; diagnostic imaging; sonography
• ISSN: 0361-803X; 1546-3141
• DOI: 10.2214/AJR.13.12334

The purpose of this article is to examine the rates of appendiceal visualization by sonography, imaging-based diagnoses of appendicitis, and CT use after appendiceal sonography, before and after the introduction of a sonographic algorithm involving sequential changes in patient positioning. We used a search engine to retrospectively identify patients who underwent graded-compression sonography for suspected appendicitis during 6-month periods before (period 1; 419 patients) and after (period 2; 486 patients) implementation of a new three-step positional sonographic algorithm. The new algorithm included initial conventional supine scanning and, as long as the appendix remained nonvisualized, left posterior oblique scanning and then "second-look" supine scanning. Abdominal CT within 7 days after sonography was recorded. Between periods 1 and 2, appendiceal visualization on sonography increased from 31.0% to 52.5% (p < 0.001), postsonography CT use decreased from 31.3% to 17.7% (p < 0.001), and the proportion of imaging-based diagnoses of appendicitis made by sonography increased from 63.8% to 85.7% (p = 0.002). The incidence of appendicitis diagnosed by imaging (either sonography or CT) remained similar at 16.5% and 17.3%, respectively (p = 0.790). Sensitivity and overall accuracy were 57.8% (95% CI, 44.8-70.1%) and 93.0% (95% CI, 90.1-95.3%), respectively, in period 1 and 76.5% (95% CI, 65.8-85.2%) and 95.4% (95% CI, 93.1-97.1%), respectively, in period 2. Similar findings were observed for adults and children. Implementation of an ultrasound algorithm with sequential positioning significantly improved the appendiceal visualization rate and the proportion of imaging-based diagnoses of appendicitis made by ultrasound, enabling a concomitant decrease in abdominal CT use in both children and adults.