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Springer Science+Business Media New York 2014 Published online: 14 October 2014
Abdom Imaging (2015) 40:609610 DOI: 10.1007/s00261-014-0269-8
Abdominal
Imaging
The cobra head sign
Philippe A. Tirman, Raymond B. Dyer
Department of Radiology, Wake Forest Baptist Medical Center, Wake Forest University School of Medicine, Medical Center Blvd, Winston-Salem, NC 27157, USA
Unlike the deadly reptile for which it is named (Fig. 1), the cobra head sign is used to describe the usually incidental and benign finding of an orthotopic, intravesical ureterocele (previously referred as a simple ureterocele) [1]. When opacified with contrast material, the ureterocele mimics the cobras head protruding into the urinary bladder lumen, with the upstream ureter serving as the snakes body (Fig. 2). Although the sign was originally described on standard radiographic images, it may appear on MR or CT urography (Fig. 3, 4). For those that relate more to botany than herpetology, this appearance has also been referred as the...