An Unexpected Adverse Event during Colonoscopy Screening: Bochdalek Hernia.

Bochdalek hernia (BH) is defined as herniated abdominal contents appearing throughout the posterolateral segment of the diaphragm. It is usually observed during the prenatal or newborn period. Here, we report a case of an adult patient with herniated omentum and colon due to BH that was discovered during a colonoscopy. A 41-year-old woman was referred to our hospital with severe left chest and abdominal pain that began during a colonoscopy. Her chest radiography showed colonic shadow filling in the lower half of the left thoracic cavity. A computed tomography scan revealed an approximately 6-cm-sized left posterolateral diaphragmatic defect and a herniated omentum in the colon. The patient underwent thoracoscopic surgery, during which, the diaphragmatic defect was closed and herniated omentum was repaired. The patient was discharged without further complications. To the best of our knowledge, this case is the first report of BH in an adult found during a routine colonoscopy screening.