RESUMEN
Referrals for bariatric surgery have currently increased due to the need for more effective interventions in the management of severely obese patients. The Roux-en-Y gastric bypass is currently one of the preferred procedures, and internal hernias are the main causes of late postoperative complication. Petersen's hernia is a less common finding in most published papers compared to transmesocolic hernia, however, it seems to be increasing in incidence (in our service, eight cases which have been tomographic diagnosed in 2 years, were confirmed by laparoscopic surgery). The clinical findings are not specific, usually with abdominal pain, associated or not with abdominal distention and vomiting. In this context, imaging exams have an important role in the early diagnosis and surgery of this condition, with multislice computed tomography being the most accurate method. The aim of this pictorial essay is to the demonstrate the main CT findings associated with Petersen's hernia in patients who underwent Roux-en-Y gastric bypass.