Magnetic Resonance Imaging (MRI) can be used to detect acute appendicitis in pregnant women, according to a study conducted by a team of Harvard Medical School (HMS) professors. Untreated acute appendicitis can be fatal to both the mother and fetus.

Acute appendicitis is a rare condition, occurring in less than one percent of pregnant women and in about the same percentage of the general population, said Ivan Pedrosa, an assistant professor at HMS who worked on the study published in Consumer Health Daily.

According to Pedrosa, many women experience abdominal pain while pregnant. Though the likelihood of a woman having appendicitis is low, doctors need a way to test for the condition, Pedrosa said.

“The problem is that abdominal pain is very common during pregnancy for other reasons” Pedrosa said. “The challenge for us is to be able to distinguish those situations where abdominal pain may be related to more trivial conditions...from those situations where surgical treatment is needed like acute appendicitis.”

Though Pedrosa said the ultrasound remains the first tool used in diagnosis because it is fast and harmless to the fetus, when the ultrasound is inconclusive, MRIs may provide a clearer picture.

“The still ultrasound is the imaging test of choice in the evaluation of pregnant patients with abdominal pain, because it’s fast, relatively inexpensive and it doesn’t use radiation,” Pedrosa said.

MRIs are also safe for the fetus, but are more expensive than ultrasound, making them a less common tool.

Catscans, used previously when ultrasounds did not provide sufficient information, relied on radiation harmful to the fetus, Pedrosa said.

The study found that MRIs can also diagnose causes of abdominal pain other than appendicitis.

“We were able to not only exclude the diagnosis of acute appendicitis but also to provide an alternative diagnosis that could explain the symptoms,” said Pedrosa. “That actually includes some patients in whom we did recognize other sources of abdominal pain that require surgical treatment, like for example ovarian torsion and recognize degenerative fibroids, benign tumors in the uterus.”

The researchers conducted the study on 51 pregnant women who came to the hospital to get catscans by also offering them free MRIs.

According to Deborah Levine, assistant professor at HMS and an author of the study, the use of MRIs on pregnant women is rapidly expanding, as researchers have discovered increased uses for the scan.

Levine said “one of our big projects is using MRI to evaluate the fetus when there’s an abnormality that’s not easily assessed with ultrasound, especially abnormalities of the brain.”