Testicular appendix

A testicular appendix (alternatively called appendix of testis or appendix testis, and historically also known as hydatid of Morgagni) represents a developmental remnant of the paramesonephric duct (Müllerian duct) which is situated in the upper pole of the testis inside a groove between the testicle and the head of epididymis 1.

The prevalence in childhood is around 85% (range 83-92%). The testicular appendix can be bilateral in 69% of the cases 4.

Testicular appendages in general alone have no clinical significance. However, when complicated by torsion, they can lead to acute scrotum 2.

Ultrasonography with high-frequency linear array transducers is the modality of choice in the evaluation of scrotum and testis with its appendages. It can quickly and easily demonstrate the existence of such anatomic structures, their vascularity and without exposure to radiation. Being a bedside examination, the ultrasonographer can directly take history and examine the patient. It is of note that the appendages of the testis are best seen when combined with hydrocele. The frequency of the ultrasonographic identification of these anatomic structures is around 89% 3.

It is important to remember that the normal testicular appendix is usually seen as an oval, sessile structure in 88% of the cases 4. Its length ranges from 1-7 mm 1. Color Doppler ultrasonography can occasionally detect blood flow inside testicular appendages 4. Finally, when stalked, the appendix is in danger of torsion.

In cases of torsion, patients present with acute scrotum and imaging differential diagnosis includes:

Anatomy: Abdominopelvic

Anatomy: Abdominopelvic

Article information

rID: 26486
System: Urogenital
Section: Anatomy
Synonyms or Alternate Spellings:
  • Hydatid of Morgagni (testis)
  • Appendix testis
  • Appendix of testis
  • Testicular appendix
  • Αppendix of the testis
  • Αppendix of testis

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Cases and figures

  • Figure 1: testes and spermatic cord (Gray's illustration)
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  • Case 1: epididymis and testis appendages
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  • Case 2: appendix testis
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  • Case 3: testicular appendix in hydrocele
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