Abdominal pain during pregnancy is extremely common. Sometimes it can be severe.
How do a woman and her doctors know whether her abdominal pain is due to pregnancy or something else, for example appendicitis? Diagnosing appendicitis in a pregnant woman has always been challenging for a number of reasons. These reasons include the overlap of abdominal pain symptoms between appendicitis and normal pregnancy, the higher likelihood of non-classic symptoms with appendicitis during pregnancy, anatomic changes related to the enlarged uterus pushing other abdominal structures and organs aside, and the physiologic leukocytosis that occurs during pregnancy (physical stressors like infections and pregnancy may cause the white blood cell count to rise). These factors can lead to the development of complications (i.e. perforation of the appendix with peritonitis) from a delay in diagnosis and treatment plus misdiagnosis resulting in a negative appendectomy.
In the largest study done to date which included close to 100,000 patients, appendectomy for a perforated appendix was associated with a six percent rate of fetal loss and an 11 percent rate of early delivery while, for a negative appendectomy, the rate of fetal loss was four percent and early delivery was 10 percent. Traditionally, the use of any X ray technology in pregnant women was avoided due to potential negative effects on the unborn child due to ionizing radiation. Diagnosing appendicitis in general, relies on physical exam, white blood cell counts, and CT scans (which use radiation). So traditionally, other imaging methods have been used on pregnant women. Sonograms are poor tests to assess the appendix, visualizing the appendix in less than two percent of non-pregnant patients. The American College of Radiology recommends MRIs for diagnosing appendicitis in pregnant women. The problem with using MRI technology, which utilizes powerful magnets without any radiation, is that many ERs do not have MRIs available, especially in rural areas. Plus, because the abdominal organs may be distorted due to pregnancy, a radiologist certified in reading MRIs should interpret the scan. Again, some ERs do not have a radiologist available 24/7 to interpret the scans.
Fortunately (or perhaps unfortunately), there is an extensive body of knowledge available on the effects of radiation on a fetus. It comes from studies of atomic bomb survivors. It turns out that the lowest documented radiation dose associated with birth defects is 610 mGy (milligrays).
Even in the first trimester, where the fetus is most vulnerable, there are no reports of birth defects reported with doses below 50 mGy. The actual radiation dose associated with a CT scan is 10 to 25 mGy while the fetal dosage is usually less than 5 mGy. Therefore, because of maternal/fetal complications related to missed and delayed diagnoses of appendicitis plus complications of surgery on pregnant women who actually do not have appendicitis (negative appendectomy), many experts now recommend using CT scans on these women to help confirm or rule out the diagnosis of appendicitis and prevent complications.