Accuracy of Point-of-care Ultrasound in Diagnosing Acute Appendicitis During Pregnancy

Acute appendicitis is the most common non-obstetrical surgical emergency in pregnancy. Ultrasound is the imaging tool of choice, but its use is complicated due to anatomical changes during pregnancy and depends on the clinician's expertise. In this study, our aim was to investigate the diagnostic accuracy of point-of-care ultrasound (POCUS) in suspected appendicitis in pregnant women.

We conducted a retrospective analysis of all pregnant women undergoing POCUS for suspected appendicitis between June 2010-June 2020 in a tertiary emergency department. The primary outcome was to establish sensitivity, specificity, and likelihood ratios of POCUS in diagnosing acute appendicitis, overall and for each trimester. We used histology of the appendix as the reference standard in case of surgery. If appendectomy was not performed, the clinical course until childbirth was used to rule out appendicitis. If the patients underwent magnetic resonance imaging (MRI), we compared readings to POCUS.

A total of 61 women were included in the study, of whom 34 (55.7%) underwent appendectomy and in 30 (49.2%) an acute appendicitis was histopathologically confirmed. Sensitivity of POCUS was 66.7% (confidence interval [CI] 95% 47.1-82.7), specificity 96.8% (CI 95% 83.3-99.9), and positive likelihood ratio 20.7. Performance of POCUS was comparable in all trimesters, with highest sensitivity in the first trimester (72.7%). The MRI reading showed a sensitivity of 84.6% and a specificity of 100%. In the four negative appendectomies a MRI was not performed.

Point-of-care ultrasound showed a high specificity and positive likelihood ratio in diagnosing acute appendicitis in pregnant women in all trimesters with suspected appendicitis. In negative (or inconclusive) cases further imaging as MRI could be helpful to avoid negative appendectomy.