Merry Christmas everyone! For your reading pleasure this week, Id thought we would discuss a case whose topic is near and dear to my heart. In the most recent issue of EPMonthly, there is a great case and interesting “internal” discussion made quite humorously public by Drs. Pregerson and T. Wu of a young healthy male with right lower quadrant abdominal pain after eating at a “Roach Coach”…. which just so happen to have the best breakfast burritos, but I digress… The case discussion involves how the history and physical may help, how labs may (or may not) help and how an ultrasound can be of use to make you and your surgical colleagues feel better in taking the patient to the OR. There was a recent post on SonoSpot about ultrasound in appendicitis sharing data from a study about the CT findings when US “equivocal” cases arise. When the ultrasound is positive – how great is that?! Quite a few studies recently on the topic and some of the more recent ones can be found here.
The case is followed by an extensive (and great) discussion of the technique, pearls and pitfalls of ultrasound in evaluating the appendix – because we all know there are quite a few. As far as the sensitivity ad specificity go, they state it best:
“Sensitivity & Specificity: Both the sensitivity & specificity of ultrasound for appendicitis are less than that of CT. In pediatrics the values are about 88% and 94% respectively, and in adults about 83% and 93%. (These numbers may vary depending on the experience of the ultrasonographer.) There are studies from Europe and Israel where they have used the “ultrasound first” approach for many, many years that show even better test characteristics. These values are actually not that bad when compared to CT scan whose sensitivity and specificity are around 94% and 95% respectively. Remember, however, that the performance characteristics for ultrasound can be significantly worse in overweight patients or those with overlying bowel gas. In addition, if the appendix is retrocecal or is lying in a difficult anatomical plane, the study will be more challenging. Unfortunately, you may still have to do a CT scan if your ultrasound is non-diagnostic and your clinical suspicion is moderate to high, but the strategy of ultrasound first would likely decrease CTs by about 50%.”
And in kids…”You should be aware of the most recent recommendation of the American College of Radiology from the “Choosing Wisely” campaign, which states, “Don’t do computed tomography (CT) for the evaluation of suspected appendicitis in children until after ultrasound has been considered as an option.” Although CT is accurate in the evaluation of suspected appendicitis in the pediatric population, ultrasound is nearly as good in experienced hands. Since ultrasound will reduce radiation exposure, ultrasound is the preferred initial consideration for imaging examination in children. If the results of the ultrasound exam are equivocal, it may be followed by CT. This approach is cost-effective, reduces potential radiation risks and has excellent accuracy, with reported sensitivity and specificity of 94 percent.”
To diagnose appendicitis: look for a noncompressible a-peristaltic structure that attaches to the cecum that is larger than 7mm in diameter.
A great tutorial of ultrasound for the appendix can be found here by the UltrasoundPodcast guys:
SonoSpot: Topics in Bedside Ultrasound 