Svati Singla Long, Abstract Co-Author: Nothing to Disclose

Christopher M. Long PhD, Abstract Co-Author: Nothing to Disclose

Hong C. Lai MPH, Abstract Co-Author: Nothing to Disclose

Katarzyna J. Macura MD, PhD, Presenter: Nothing to Disclose

We formulated the following PIO (P-patient group, I- intervention/imaging, O-outcome) clinical question: In pregnant patients with right lower quadrant pain, suspected appendicitis, what is the expected sensitivity and specificity of magnetic resonance imaging (MRI) for the diagnosis of acute appendicitis?

A systematic search of the literature using PUBMED was performed to identify studies that addressed the clinical question, leading to 42 citations. Subsequent focused review of the literature aimed to investigate the utility of MRI in ruling in or ruling out acute appendicitis in pregnant women with right lower quadrant pain and suspected appendicitis. A total of 6 papers met the inclusion criteria. The studies used MRI criteria for the diagnosis of acute appendicitis that primarily involved the diameter of the appendix and the presence/absence of periappendiceal fat stranding. To obtain summary estimates of sensitivity and specificity, positive predictive value (PPV) and negative predictive value (NPV), and account for a possible correlation between sensitivities and specificities, a bivariate random-effects model was used to perform meta-analysis. The SAS software (version 9.2) was used to perform statistical analysis.

The pooled sensitivity and specificity and their corresponding 95% confidence interval (CI) derived from the random-effects models are pooled sensitivity 0.91 (95% CI: 0.54, 0.99) and pooled specificity 0.98 (95%CI: 0.87, 0.99). The pooled PPV and NPV and their corresponding 95% CI derived from the random-effects models are pooled PPV 0.86 (95%CI: 0.38, 0.98), and pooled NPV 0.99 (95%CI: 0.93, 0.99).

The diagnostic strength of MRI is in its high specificity and high negative predictive value. Finding a normal appendix on MRI yields high accuracy in excluding acute appendicitis. Since cases of the nonvisualized appendix on MRI pose a diagnostic difficulty, further studies are needed to improve imaging protocols to decrease the incidence of nonvisualized appendix.

MRI provides a valuable tool for the evaluation of pregnant patients with right lower quadrant pain and can help avoid unnecessary laparatomies and radiation exposure from computed tomography.

Singla Long, S, Long, C, Lai, H, Macura, K, Evidence Assessment in Support of Utilization of MRI to Evaluate Right Lower Quadrant Pain in Pregnant Women: A Meta-Analysis.  Radiological Society of North America 2010 Scientific Assembly and Annual Meeting, November 28 - December 3, 2010 ,Chicago IL. http://archive.rsna.org/2010/9009371.html