Bell clapper deformity

Last revised by Calum Worsley on 01 Sep 2021

A bell clapper deformity is a predisposing factor in testicular torsion in which the tunica vaginalis has an abnormally high attachment to the spermatic cord, leaving the testis free to rotate. Bell clapper deformity predisposes to intravaginal torsion of the testis.

It is best defined as the complete investment of the testis, epididymis and a portion of the spermatic cord by the tunica vaginalis. It has a reported occurrence of 5-16% and is seen bilaterality in 66-100% 1,2.

History and etymology

The term was first reported in the literature in 1932 by Muschat who described the testes “hanging freely in the vaginal sac like a clapper in a bell” 3.

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Cases and figures

  • Figure 1: normal anatomy
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  • Figure 2: bell clapper deformity
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  • Figure 3: bell clapper deformity with torsion
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  • Figure 4: bell clapper (photo)
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