Searching for certainty: findings predictive of appendicitis in equivocal ultrasound exams.
BACKGROUND
Ultrasound (US) is the preferred imaging modality for evaluating suspected pediatric appendicitis. However, borderline appendiceal enlargement or questionable inflammatory changes can confound interpretation and lead to equivocal exams.


OBJECTIVE
The purpose of this study was to determine which findings on equivocal US exams are most predictive of appendicitis.


METHODS
All US exams performed for suspected pediatric appendicitis from July 1, 2013, through July 9, 2014, were initially interpreted using a risk-stratified scoring system. Two blinded pediatric radiologists independently reviewed US exams designated as equivocal and recorded the following findings: increased wall thickness, loss of mural stratification, peri-appendiceal fat inflammation, peri-appendiceal fluid, appendicolith and maximum appendiceal diameter. A third pediatric radiologist resolved discrepancies. US features were correlated with the final diagnosis via multivariate analysis.


RESULTS
During the study period, 162/3,750 (4.3%) children had US exams initially interpreted as equivocal (mean age 9.8 +/- 3.8 years). Five outpatients were lost to follow-up. Forty-eight of the remaining 157 (30.6%) children had an operative diagnosis of appendicitis. Findings significantly associated with appendicitis were loss of mural stratification (odds ratio [OR] = 6.7, P=0.035), peri-appendiceal fat inflammation (OR = 10.0, P<0.0001) and appendicolith (OR = 15.8, P=0.025). While appendiceal diameter tended to be larger in patients with appendicitis, the difference was not statistically significant.


CONCLUSIONS
Loss of mural stratification, peri-appendiceal fat inflammation and an appendicolith are significant predictors of appendicitis in children with otherwise equivocal US exams. While maximum appendiceal diameter is not statistically associated with appendicitis in our study, mean appendiceal diameter of 6.7 mm in those without appendicitis suggests that the customary upper normal limit of 6 mm is too sensitive.
Department of Diagnostic Radiology, Baylor College of Medicine, One Baylor Plaza, Mail Stop BCM 360, Houston, TX, 77030, USA. telesman@bcm.edu.
Morgan E
ME
Telesmanich
Edward B. Singleton Department of Pediatric Radiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Robert C
RC
Orth
Outcomes and Impact Services, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Wei
W
Zhang
Department of Pediatric Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Monica E
ME
Lopez
Department of Pediatric Surgery, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Jennifer L
JL
Carpenter
Edward B. Singleton Department of Pediatric Radiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Nadia
N
Mahmood
Edward B. Singleton Department of Pediatric Radiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
Siddharth P
SP
Jadhav
Edward B. Singleton Department of Pediatric Radiology, Texas Children's Hospital, Baylor College of Medicine, Houston, TX, USA.
R Paul
RP
Guillerman
D000293:Adolescent; D001064:Appendicitis / Q000000981:diagnostic imaging*; D002648:Child; D002675:Child, Preschool; D003937:Diagnosis, Differential; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D014463:Ultrasonography / Q000379:methods*; D055815:Young Adult
Appendicitis; Appendix; Children; Equivocal; Predictors; Ultrasound