Deciduosis of the Appendix During Pregnancy.

Acute appendicitis is an important differential diagnosis in patients with right lower quadrant pain during pregnancy. Endometriosis, a hormone-related pathology, is another possibility. Patients with endometriosis are typically symptomatic before pregnancy. Stromal endometriosis is a variant of endometriosis that presents no symptoms before pregnancy but which occasionally presents with the new onset of symptoms during pregnancy. We report the case of a 35-year-old woman in her 8th month of pregnancy who presented with impending appendiceal rupture due to deciduosis of the appendix, a progesterone-related condition, during pregnancy. This case suggests that deciduosis/stromal endometriosis should be considered as a differential diagnosis of acute abdomen during pregnancy, even if the patient is asymptomatic before pregnancy.