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 presence of this cobra head appearance is an indicator of uncomplicated ureterocele.
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.
- inanimate object inspired
vegetable and plant inspired
- celery stalk metaphysis
- celery stalk anterior cruciate ligament
- chocolate cyst
- coffee bean sign
- cottage loaf sign
- cotton wool appearance of bone
- doughnut sign
- linguine sign
- miliary opacities
- onion skin periosteal reaction
- pancake brain
- pancake vertebra
- popcorn calcification
- salt and pepper skull
- rice grain calcification
- tree in bud
- waterlily sign
- fruit inspired
animal and animal produce inspired
- fish and seafood
- poulty and foul
- domesticated and wild animals
- insects and bugs
- mythical creatures
- processed animal product containing foods
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- 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
- 2. Chavhan GB. The cobra head sign. Radiology. 2002;225 (3): 781-2. Radiology (full text) - doi:10.1148/radiol.2253011206 - Pubmed citation
Synonyms & Alternative Spellings
|Synonyms or Alternative Spelling||Include in Listings?|
|Adder head sign||✓|
|Adder's head sign||✗|
|Spring onion sign||✓|
|Cobra's head sign||✗|