PEM Pearl: Pediatric appendicitis
Studies show that the appendix is not visualized on 10% of abdominal ultrasounds (seems like a gross UNDERestimation). This of course leads to more radiation and delays in diagnosis. Wouldn't it be nice to use US to help rule out appendicitis even when we can't directly visualize the appendix??
This study aims to do just that. This was a single center, retrospective review of 1756 encounters to a Peds ED in Spain. Patients aged 3-13 (median 10.1) with clinical suspicion for appy were included. The main outcome was diagnosis of acute appendicitis as determined by surgical pathology. There were 293 (17.8%) cases of acute appendicitis. Those with no documentation of appendectomy within 7 days were considered not to have had appendicitis. Interestingly, the US was performed by a radiologist or radiology resident, probably contributing to their exceedingly low non-visualization rate.
They found that several indirect US findings were suggestive of appendicitis, such as free fluid, lymphadenopathies, phlegmon in the area of the appendix, and inflammation of the peri-appendiceal fat. They had a large number of non-visualized appendixes (>500), and found that the absence of both free fluid and peri-appendiceal fat inflammation were most helpful in ruling out acute appendicitis. In patients with an Alvarado score <7 (meaning low-moderate likelihood), combined with the absence of these findings, the negative-predictive value is 99.4%.
Bottom line: even if the appendix is not visualized, US can be helpful in ruling out appendicitis in patients with an Alvarado score under 7, no free fluid, and no peri-appendiceal fat inflammation.
This study aims to do just that. This was a single center, retrospective review of 1756 encounters to a Peds ED in Spain. Patients aged 3-13 (median 10.1) with clinical suspicion for appy were included. The main outcome was diagnosis of acute appendicitis as determined by surgical pathology. There were 293 (17.8%) cases of acute appendicitis. Those with no documentation of appendectomy within 7 days were considered not to have had appendicitis. Interestingly, the US was performed by a radiologist or radiology resident, probably contributing to their exceedingly low non-visualization rate.
They found that several indirect US findings were suggestive of appendicitis, such as free fluid, lymphadenopathies, phlegmon in the area of the appendix, and inflammation of the peri-appendiceal fat. They had a large number of non-visualized appendixes (>500), and found that the absence of both free fluid and peri-appendiceal fat inflammation were most helpful in ruling out acute appendicitis. In patients with an Alvarado score <7 (meaning low-moderate likelihood), combined with the absence of these findings, the negative-predictive value is 99.4%.
Bottom line: even if the appendix is not visualized, US can be helpful in ruling out appendicitis in patients with an Alvarado score under 7, no free fluid, and no peri-appendiceal fat inflammation.
