Bochdalek hernia

Imaging description A Bochdalek hernia is a defect of the posterior hemidiaphragm with protrusion of abdominal content, usually fat, into the thorax [1]. It may occur on either side, but is more common on the left side due to a protective barrier effect of the liver [1, 2]. CT typically demonstrates the diaphragmatic defect with abdominal fat or omentum protruding through the defect [1–4] (Figure 71.1). Less commonly, retroperitoneal or intraperitoneal organs may herniate through the defect [3] (Figures 71.2 and 71.3). The kidney is the most common organ to herniate through the defect, followed by the spleen [3]. Importance Bochdalek hernias are present in approximately 6% of adults, with incidence increasing with age [2]. The vast majority of Bochdalek hernias occurring in adults are inconsequential [1, 2]. Rarely, incarceration of hernia content may occur [3]. Lack of familiarity with the typical imaging appearance of a Bochdalek hernia may lead to unnecessary work up as it may be mistaken for an indeterminate mass or diaphragmatic injury.