Epididymal appendix

An epididymal appendix (or alternatively appendix of the epididymis or appendix epididymis) is a testicular appendage that is a developmental remnant of the mesonephric duct (Wolffian duct) which can be found in the head of the epididymis 1. In 78% of the cases, it is stalked and is thus easily subject to torsion 2.

Normally, epididymal appendages are of no clinical significance, but when torted they can cause an acute scrotum in children 2. After torsion of its pedicle, the appendage may fall inside the scrotum and give the appearance of minute mobile particles 3.

Ultrasonography with a high-frequency linear transducer can reliably evaluate the appendix along with its vascularity. Its reported frequency in ultrasonography is ~12.5% (range 6-17%) 3.

The appendix of the epididymis, similarly to the appendix of the testis, is normally oval in shape, sessile or may be “stalk-like” or pedunculated 1. They appear iso- or hyperechogenic to the epididymis parenchyma. Sometimes, calcifications may be found. In general, the epididymis appendix is best seen when floating in a hydrocele.

When torted, it is a cause of acute scrotum and imaging differential diagnosis should include:

Anatomy: Abdominopelvic
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Article information

rID: 26487
System: Urogenital
Section: Anatomy
Synonyms or Alternate Spellings:
  • Appendix epididymis

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Cases and figures

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    Case 1: epididymis and testis appendages
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    Case 2: epididymal appendix
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    Gray-scale high r...
    Case 3: epididymal and testicular appendages
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