Testicular appendix

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

Epidemiology

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

Clinical presentation

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

Radiographic features

Ultrasound

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 hydrocoele. 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. Colour Doppler ultrasonography can occasionally detect blood flow inside testicular appendages ⁴. Finally, when stalked, the appendix is in danger of torsion.

Differential diagnosis

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

• testicular torsion
• epididymo-orchitis
• acute idiopathic scrotal oedema