This site is targeted at medical and radiology professionals, contains user contributed content, and material that may be confusing to a lay audience. Use of this site implies acceptance of our Terms of Use.

Cobra head sign

Dr Yuranga Weerakkody and Radswiki et al.

The cobra head sign (or spring onion sign) refers to dilatation of the distal ureter, surrounded by a thin lucent line, which is seen in patients with an adult-type ureterocoele.

The lucent hood represents the combined thickness of the ureteral wall and prolapsed bladder mucosa, outlined by contrast material within the bladder lumen.

This lucent line should be thin and well defined. Any thickening, irregularity, or loss of definition of the cobra’s hood should raise concern for the presence of a pseudoureterocoele.

This article is a stub, which means it needs more content. You can contribute to Radiopaedia.org too. Just register and edit... every little bit helps.

References

This article is in need of some more references!
You can make a difference to Radiopaedia.org by adding some relevant ones.
1. Dyer RB, Chen MY, Zagoria RJ. Classic signs in uroradiology. Radiographics. 2004;24 Suppl 1 : S247-80. doi:10.1148/rg.24si045509 - Pubmed citation