Appendicitis during pregnancy is a relatively rare condition, though it is thought that the incidence is similar to that of the non-gravid population at approximately 1 in 1500 pregnancies. The majority of appendicitis in pregnancy occurs during the second trimester when they are difficult to diagnose both clinically and by imaging.

The clinical presentation of appendicitis is usually typical in early pregnancy (right lower quadrant pain, nausea/vomiting) but becomes more non-specific with advancing pregnancy. As pregnancy progresses the appendix migrates cephalad towards the right costal margin and may lead to pain referred to this location. Due to the lack of specificity of the preoperative evaluation, the pathologic diagnosis of appendicitis is confirmed in only 30% to 50% of cases.

Additionally, timely intervention is crucial as there the fetal loss rate approaches 40% for perforated appendicitis. Therefore, imaging plays an important role in timely and accurate diagnosis.
Graded compression ultrasound is commonly the initial imaging modality employed. Helical CT is a viable alternative but is typically avoided secondary to the relatively high fetal radiation dose. MR is emerging as an alternative for those patients that have a equivocal or non-diagnostic ultrasound examination but with continued high clinical suspicion of appendicitis. Findings on MR are similar to those seen on CT. The appendix is fluid distended to greater than 6-7mm in diameter with surrounding peri-appendiceal mesenteric fat stranding. When present, the appendicolith is less well visualized than on CT or ultrasound.

The management of appendicitis is similarly surgical, either by laparotomy or laparoscopy. The prognosis is similar to that of non-gravid patients.

Esben Vogelius, MD

1. Pastore PA, Loomis DM, Sauret J. Appendicitis in Pregnancy. J Am Board Fam Med 2006;19(6):621-626.
2. Pedrosa I, et al. MR Imaging Evaluation of Acute Appendicitis in Pregnancy. Radiology 2006;238:891-899.
Credit: Dr Esben Vogelius