Perforated Appendicitis With Deciduosis and Free Air Under the Diaphragm During Pregnancy

Appendicitis is the leading non-obstetric surgical emergency during pregnancy. Its diagnosis is complicated by pregnancy-related anatomical changes and poses significant risks for maternal and fetal mortality and morbidity. This report describes a rare case of perforated appendicitis with deciduosis and free air under the diaphragm during pregnancy. A 28-year-old woman presented with severe right lower and middle abdominal pain and signs of inflammation at 31 weeks of gestation. Contrast-enhanced computed tomography revealed free air under the right diaphragm with no evidence of acute perforated appendicitis or peri-appendiceal free air. Suspecting idiopathic gastrointestinal perforation, exploratory surgery was planned following an emergency cesarean section. Exploratory surgery revealed perforated appendicitis with an abscess. Histological examination revealed deciduosis of the appendicitis with a perforation. If appendicitis cannot be identified on imaging during pregnancy and free air is present under the diaphragm, it is necessary to consider the possibility of perforated appendicitis with deciduosis, in addition to idiopathic intestinal perforation.