Torsion of the spermatic cord: the main gray-scale and doppler sonographic signs

Scrotal ultrasonography (US) is usually the initial imaging modality for evaluating patients who present with acute pathologic conditions of the scrotum. Acute epididymitis, acute epididymo-orchitis, torsion of the spermatic cord (TSC), and other acute scrotal abnormalities may have similar findings at clinical examination. Pain and swelling make the clinical examination difficult, sometimes practically impossible, potentially resulting in management delays. The objective of this review is to summarize the main clinical signs of the TSC and to illustrate and briefly discuss the US features of this entity, including gray-scale imaging, color Doppler with spectral analysis, and power Doppler sonography. Although TSC can occur at any age, it is most common in adolescent boys. The intensity of the symptoms and the US findings vary with the duration of the torsion, number of twists in the spermatic cord (degree of rotation), and how tightly the vessels of the cord are compressed. An enlarged, more spherical, and diffusely hypoechogenic testis without detectable arterial and venous testicular flow at color and power Doppler US is considered diagnostic of acute testicular ischemia. The presence of a color or power Doppler signal in one part of the testis does not exclude TSC. Positive blood flow but significantly diminished, usually near or inside the mediastinum, may be found, mainly in the partial or incomplete TSC. Identification of a large echogenic extratesticular mass distal to the site of the torsion, frequently misinterpreted as a chronic epididymitis, can be the key to the diagnosis of TSC. When a small arterial sign is found a low amplitude waveform is present with an increased resistive index on the affected side due to a diminished, absent, or reversed diastolic flow. Gray-scale imaging, color Doppler, power Doppler and pulsed Doppler with spectral analysis are very effective to make or exclude the diagnosis of TSC.