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A 15-year-old boy presented with acute severe scrotal pain of nearly twelve hours duration. Swelling and tenderness in the left side of scrotum on local examination.

High resolution ultrasonography of the scrotum was done.

Longitudinal section of the left side of scrotum shows abnormal axis of the left Testis (seen in cross section here, implying 90° rotation of the axis) and enlarged epididymis / distal spermatic cord.

Transverse section of the left side of scrotum shows abnormal axis of the left Testis (seen in longitudinal section here, implying 90° rotation of the axis).

No intratesticular vascularity is seen on Power Doppler Ultrasonography.

3D Ultrasonogam shows torsion of the distal Spermatic cord close to epididymal head.

This is how realtime 3D utlrasonogaphy (also called 4D ultrasonography) is done. The actual scan is seen in the upper left; sagittal and coronal realtime reformations are seen in the upper right and lower left respectivley and the 3D reformation is seen in the lower right.

3D ultrasonographic image of the torsion (from the patient’s scan) compared with an operative specimen photograph from a different patient [image taken from Reference 2 below]

Diagnosis: Testicular Torsion.

Torsion of the spermatic cord with interruption of testicular blood flow results in acutely intense testicular pain. Testicular torsion is generally associated with various degrees of anomalous reflection of the visceral tunica vaginalis such that it envelops to greater degrees the epididymis and spermatic cord. This allows the testicle to rotate freely within the scrotum, where it can result in torsion of the spermatic cord and interruption of testicular blood flow. The bell clapper deformity occurs when the visceral tunica vaginalis extends completely around the testicle and epididymis to envelop a length of the spermatic cord. [from Reference 3 below]

Torsion of the spermatic cord occurs most commonly at 12 to 18 years but can occur at any age. Experimental studies indicate that 720° torsion is required to occlude the testicular artery. When torsion is 180° or less, diminished flow is seen. Low- and high-grade torsion shows an absence of flow after 4 hours. Torsion results in swelling and edema of the testis, and as the edema increases, testicular perfusion is further altered. Thus the findings on ultrasonography can be variable depending on the degree of torsion and its duration. [from Reference 3 below]

Gray scale ultrasonographic findings early in torsion can be those of a normal-appearing testicle. However, color and pulsed Doppler imaging reveals the absence of blood flow in the symptomatic testis. Later, enlargement of the epididymis and a hydrocele may be seen. With prolonged torsion, the testis may increase in size and become increasingly heterogeneous in both echogenicity and echo texture. Late in torsion, hemorrhagic infarction occurs, and echogenic regions of hemorrhage can be seen mixed with the hypoechoic testicular parenchyma. After infarction, the testicle may increase in echogenicity and become smaller. Color and pulsed Doppler imaging is imperative for the evaluation of torsion. The overlap in gray scale imaging findings between torsion and epididymitis or epididymo-orchitis is too great for confidently making an early diagnosis of testicular torsion when testis salvage is possible. Color and pulsed Doppler evaluation in neonates and prepubertal children requires sensitive instruments that can detect the low rate of testicular blood flow found in these age groups. It is important to always scan the asymptomatic testicle, which should have normal flow. Abnormal flow in the asymptomatic testicle may indicate improper Doppler settings. After 6 hours of torsion, the testicle undergoes irreparable damage. Torsion of the appendix testis or the appendix epididymidis can also result in acute scrotal pain. However, normal or, more commonly, increased intratesticular flow is detectable, which excludes testicular torsion in the setting in which the acute pain is persistent. Also, an enlarged appendix testis may be seen in conjunction with a hydrocele. [from Reference 3 below]

References & Further Reading:

1. Mayo Clinic article on Testicular Torsion.
2. Winter T. Ultrasonography of the scrotum. Appl Radiol 2002;31: 9-18 [Full text article. Subscription required, free]
3. Ragheb D, Higgins JL. Ultrasonography of the Scrotum: Technique, Anatomy, and Pathologic Entities. J Ultrasound Med 2002 21: 171-185. [Full text article, free in India. Subscription required for others.]
4. Dogra VS, Gottlieb RH, Oka M, Rubens DJ. Sonography of the Scrotum. Radiology 2003 227: 18-36 [Full text article, free]
5. Chen P, John S. Ultrasound of the acute scrotum. Appl Radiol 2006;35: 9-17 [Full text article. Subscription required, free]
6. Goldman SM, Sandler CM. Genitourinary Imaging: The Past 40 Years. Radiology 2000 215: 313-324 [Full text article, free]

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