In pregnant women, ultrasound, which uses high-frequency sound waves, is the imaging test typically used to view the appendix. However, a woman's uterus is enlarged during pregnancy, particularly in the third trimester. The larger size often prevents ultrasound from obtaining an accurate view of the appendix.

In the past, inconclusive results from the ultrasound regarding the condition of the appendix meant additional testing. A computed axial tomography (CAT) scan was the usual method chosen by physicians but this test risked potential harm to the fetus from ionizing radiation.

In a study conducted at the Beth Israel Deaconess Medical Center in New York, researchers examined a group of pregnant women who complained of abdominal pain. Abdominal pain is a frequent complaint from women during pregnancy. With severe, acute abdominal pain, appendicitis is a common cause.

Researchers used MRI to evaluate 51 pregnant women with complaints of abdominal pain. Prior to MRI, 48 of these women had an ultrasound exam. The MRI resulted in 4 diagnosed cases of acute appendicitis of which 2 were not detected with ultrasound.

The results of the study indicate that MRI may be effective in diagnosing or ruling out appendicitis in pregnant women. In addition, MRI can detect the condition without exposing the fetus to unnecessary radiation.

Authors of the study suggest that clinical practices should be changed based on their research. Physicians should consider replacing CAT scan with MRI as the preferred method for investigating abdominal pain in pregnant women.

However, the authors note that additional studies on a larger scale need to be completed to replicate their results. This study is published in the March 2006 issue of Radiology.

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