Keren Tuvia Baron MD, Presenter: Nothing to Disclose

Elizabeth Kagan Arleo MD, Abstract Co-Author: Nothing to Disclose

Christopher Robinson, Abstract Co-Author: Nothing to Disclose

Pina Christine Sanelli MD, Abstract Co-Author: Research Consultant, Getinge AB

To compare the diagnostic performance of MRI versus CT in the evaluation of acute nontraumatic abdominal pain in pregnant patients.

Following IRB approval, a retrospective review identified all pregnant patients (n=94) at our institution who had MR or CT exams of the abdomen and/or pelvis for acute nontraumatic abdominal pain from January 2008 through December 2010.  Sixty-one MR exams were performed on 57 patients, and 44 CT exams were performed on 43 patients, including 6 patients who had both.  MR and CT exams were classified as positive if a specific diagnosis was made in the imaging report at the time of presentation and negative if no abnormality was found to account for the patient’s pain.  The imaging diagnoses were compared with pathologic data or operative findings as the primary reference standard.  If unavailable, clinical assessment with laboratory data served as the secondary reference standard.  Patients without surgically proven diagnoses were followed clinically until delivery, when possible.  Test characteristics for MR and CT were calculated and significance testing was performed.

Of 61 MR exams, 24 were considered positive for imaging diagnoses, 33 were negative, and 4 were equivocal but classified as positive for statistical analysis.  Of 44 CT exams, 24 were positive and 20 were negative.  Overall, the most common imaging diagnosis was acute appendicitis (n=8), followed equally by cholelithiasis (n=4), ectopic pregnancy (n=4), pyelonephritis (n=4), and uterine leiomyomas (n=4).  Of 94 patients, 30 had pathologically or surgically proven disease, and 64 were diagnosed clinically.  The test characteristics for MR and CT in the diagnosis of acute abdominal pain were: sensitivity 91% and 88%, specificity 85% and 90%, positive predictive value 81% and 91%, negative predictive value 94% and 85%, and diagnostic accuracy 88% and 88%, respectively.  Differences were not statistically significant (p-value > 0.05).

MRI performed as well as CT in the evaluation of acute nontraumatic abdominal pain during pregnancy.  MRI may be preferable given its lack of ionizing radiation.

In this era of heightened concern regarding medical radiation exposure, our study supports using MRI for diagnosis of acute abdominal pain during pregnancy to avoid radiation exposure to the fetus.

Tuvia Baron, K, Arleo, E, Robinson, C, Sanelli, P, Comparing the Diagnostic Performance of MRI vs CT in the Evaluation of Acute Nontraumatic Abdominal Pain During Pregnancy.  Radiological Society of North America 2011 Scientific Assembly and Annual Meeting, November 26 - December 2, 2011 ,Chicago IL. http://archive.rsna.org/2011/11034228.html