POCUS for Appendicitis: A meta-analysis with some old news and some new news
By Joshua Guttmann, MD, FRCPC
The use of point of care ultrasound (POCUS) for diagnosing acute appendicitis is well studied. Previous meta analyses have included all users of POCUS, including emergency physicians (EP), surgeons and radiologists. However, no previous meta-analysis has focused specifically on EP performed POCUS. The authors identified 17 studies that focused on EP performed POCUS. The pooled sensitivity was 84% and pooled specificity was 91%. In a subgroup of 7 studies looking at pediatric patients, pooled sensitivity was 95% and pooled specificity was 95%. They found little heterogeneity. Other non-statistically significant findings included better accuracy when a 7 mm appendix cut-off was used rather than a 6 mm appendix and better accuracy when the attending performed the POCUS rather than a resident.
This is the largest and most robust meta-analysis to date looking specifically at EP-performance of POCUS. Its conclusions are similar to previous work on this subject. POCUS is only moderately sensitive in adults and has excellent diagnostic accuracy in children. Based on the data, it would be reasonable to consult surgery for a POCUS confirmed appendicitis in an adult with a suggestive clinical picture, however a negative POCUS does not rule out appendicitis. The authors here suggest changing the cut-off for maximal appendix diameter from 6 mm to 7 mm. This is based on 3 studies as compared to 12 for the 6 mm cutoff so there does not seem to be sufficient data to change the diagnostic criteria for appendicitis, but further studies could evaluate this hypothesis. Another interesting finding is that the studies performed outside of the United States performed better than within the United States. Perhaps our ubiquitous access to CT scanning means we use ultrasound less and therefore have less accuracy. Overall, this study provides further data for the use of POCUS by EPs, especially in the pediatric population.