Ultrasound appearances of the testicular appendages: pictorial review.

Five testicular appendages are formed during development of the male genito-urinary tract, which are the remnants of the degenerating mesonephric and paramesonephric ducts. The testicular and epididymal appendages, found at the upper pole of the testis and at the head of the epididymis respectively, are the most common and have a range of appearances on ultrasound. These appendages have the ability to undergo torsion, an important differential diagnosis in the child who presents with an acute scrotum. The varying ultrasound appearances of the testicular appendages are described and illustrated. Ultrasound features of appendiceal torsion are also demonstrated.