Clinical correlation needed: What do emergency physicians do after an equivocal ultrasound for pediatric acute appendicitis?

Abstract

We view our study as a fundamental part of the incremental progress to understand how best to use US and CT imaging to diagnose pediatric appendicitis while minimizing ionizing radiation. Children at low risk for appendicitis with equivocal US are amenable to observation and reassessment prior to reimaging with US or CT.

The non-diagnostic ultrasound in appendicitis: is a non-visualized appendix the same as a negative study?

“…A recent study from the Stanford Emergency Department has shown that children with equivocal US may be amenable to observation [27], but the study is limited by using CT as their primary end-point rather than the positive or negative outcome of appendicitis. Our study is the first that we know of, to date, to look at the relationship of a non-diagnostic US and the primary outcome of the presence or absence of appendicitis.…”

Abdominal ultrasonography of the pediatric gastrointestinal tract

“…Both grayscale and color Doppler imaging are utilized with 5-MHz curved, 9-MHz linear, or 15-MHz linear transducers [58] . Ultrasound is 88% sensitive and 94% specific for the diagnosis of acute appendicitis [59] . Diagnostic criteria for appendicitis include appendiceal diameter > 6 mm (outer wall to outer wall) and associated evidence of inflammation including appendiceal non-compressibility, wall thickening > 2 mm or hyperemia, fluid-filled appendix, increased echogenicity of periappendiceal fat, and/or presence of periappendiceal fluid [58] .…”

“…Ultrasound diagnosis of perforated appendicitis is made by the presence of marked inflammatory changes in the right lower quadrant with or without visualization of the appendix, an appendicolith without visualization of the appendix, echogenic free fluid, or a fluid collection indicating peritonitis or abscess [58] . Equivocal findings on ultrasound are associated with surgical appendicitis in 12.5%-50% of cases [58,59] . Increasing the size threshold to 7.5-8 mm in equivocal cases has been shown to increase specificity and accuracy [58,60] .…”

“…Increasing the size threshold to 7.5-8 mm in equivocal cases has been shown to increase specificity and accuracy [58,60] . Children at low risk for appendicitis with equivocal ultrasound findings are amenable to observation and reassessment [59] . When the patient's white blood cell count is < 11.0 × 10 9 /L, a non-diagnostic ultrasound or non-visualized appendix on ultrasound are associated with negative predictive values of 95.59% and 96.99%, respectively [61] .…”

Ultrasound of paediatric appendicitis and its secondary sonographic signs: providing a more meaningful finding

“…While dedicated paediatric sonographers are more likely than their general counterparts to locate the appendix,32, 33 many children do not present to specialist paediatric departments. Definitive sonographic criteria or techniques that improve accuracy and assist diagnosis would be of particular benefit in these cases.…”