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Keyhole sign (posterior urethral valves)

Last revised by Dr Daniel J Bell on 02 Jan 2022

The keyhole sign is an ultrasonographic sign seen in boys with posterior urethral valves. It refers to the appearance of the proximal urethra (which is dilated) and an associated thick walled distended bladder which on ultrasound may resemble a keyhole.

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Cases and figures

  • Figure 1: keyhole (photo)
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  • Case 1: posterior urethral valves
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  • Case 2: antenatal ultrasound
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  • Case 3
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