Written by Vivian Lei
In a pregnant patient presenting with abdominal pain and suspected appendicitis, an initial ultrasound should be performed to exclude obstetric causes for abdominal pain. MRI may be a reasonable next study if it is immediately accessible and radiologists with expertise in MRI interpretation are available. Otherwise, CT should be utilized.
Why does this matter?
Pregnant patients with abdominal pain often pose a diagnostic challenge for physicians. As a result, diagnosis and treatment of appendicitis may often be delayed, resulting in increased maternal and fetal morbidity. At the same time, misdiagnosis resulting in a negative appendectomy is also associated with fetal loss.
What to do
The American College of Obstetrics and Gynecology (ACOG) and the American College of Radiology (ACR) both offer guidance on imaging in pregnancy.
Always start with ultrasound. Establish whether there is an obstetric source of abdominal pain, as these are more common in pregnant patients.
If MR imaging is available, get an MRI.
If MR imaging is not available or inconclusive, get a CT. It is quick and the most definitive imaging modality.
Radiation exposure from CT of the abdomen and pelvis is 10-25 mGy and can be decreased to 2.5 mGy with a “pregnancy protocol CT”
No reported cases of fetal anomalies, growth restriction, or abortion have been reported with radiation exposure less than 50 mGy
Bottom line: Don’t withhold definitive imaging from a pregnant patient with suspected appendicitis.
Diagnostic Imaging in Pregnant Patients With Suspected Appendicitis. JAMA. 2019 Jul 1. doi: 10.1001/jama.2019.9164. [Epub ahead of print]
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