Bare area sign

Excerpt

The posterosuperior aspect of the liver, adjacent to the posterior body wall, is not covered by peritoneum, resulting in the so-called “bare area” [1]. It is a large triangular area on the diaphragmatic surface of the liver which is attached directly to the diaphragm by loose connective tissue (Figs. 1, 2). As the bare area is devoid of peritoneum and due to the restriction of peritoneal fluid by the coronary ligaments, fluid at that site cannot be ascites, but only pleural effusion. This is called as the bare area sign (Fig. 3) [2]. Halvorsen et al., in their blinded analysis of multiple cases, concluded that no single sign was reliable, but, when all four signs (the diaphragm sign, the displaced crus sign, the interface sign, and the bare area sign) were used, accurate differentiation of ascites and pleural effusion was possible [3]. CT sections at levels above or below the bare area may cause false-positive diagnosis of ascites. Difficulty may also arise when the bare area is smaller as an anatomical variant [2]. Bare area sign is not valid in patients with liver transplantation, owing to the surgical removal of the normal peritoneal reflections [4].

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