Testicular torsion is the twisting of the testicle on the spermatic cord, resulting in strangulation of the blood supply and infarction of the testicle. The patient usually has sudden onset of pain and swelling of the involved testicle. The pain may radiate into the groin and lower abdomen; thus, it may be confused with appendicitis unless the physician examines the genitalia carefully. On physical examination, it is difficult to distinguish the testicle from the epididymis because of localized swelling. For this reason, the condition is frequently misdiagnosed as epididymitis. Age is the most useful criteria in distinguishing torsion from epididymitis, because torsion usually occurs around puberty whereas epididymitis more often occurs in sexually active men, usually after age 20 years. As the testes descend from their embryologic intra-abdominal position, they acquire coverings from the layers of the abdominal wall known as the spermatic fascia. The external spermatic fascia derives from the external oblique fascia and remains firmly attached to the tissue of the external ring. The cremasteric muscle and fascia arise from the internal oblique muscle attached laterally to the inguinal ligament and iliopsoas fascia and immediately to the pubic tubercle. The internal spermatic fascia is continuous with the transversalis fascia. The parietal and visceral tunica vaginalis surround the testis with a mesothelium-lined pouch that is derived from peritoneum. They are continuous at the posterior lateral border of the testis at its mesentery, where it is fixed to the scrotal wall. The testis is also fixed at its lower pole by the gubernaculum. Occasionally, the mesentery and gubernaculum may be deficient, leaving the testis unfixed and predisposing it to torsion of the cord. This is commonly referred to as the “bellclapper deformity.” Imaging of the testes and scrotal contents is best performed by sonography. Because of its superior anatomic visualization, sonography covers the whole spectrum of benign and malignant disease, infertility, and trauma relating to the scrotum and its contents. The normal testis has a medium level, homogeneous echotexture with a well-defined contour. The epididymis is easily demonstrable, and its echogenicity is similar to that of the testis. The introduction of color Doppler imaging has made sonography a highly accurate and specific technique in diagnosing or ruling out testicular torsion. The torsed testis usually appears normal for several hours following vascular strangulation; therefore, the ability to assess the vascular supply to the testicle makes color Doppler imaging an essential element of sonographic evaluation. 1
Color Doppler studies have resulted in an improvement in the US evaluation of testicular torsion with a claimed sensitivity and specificity of 100%. Testicular torsion was diagnosed when blood flow in the symptomatic testis was absent or markedly reduced compared with the normal side. In five of seven patients subsequently shown to have torsion, flow was absent. In two cases, a single small vessel was demonstrated. The authors concluded that depending on local availability, color Doppler US could supersede scintigraphy as the primary imaging study for excluding testicular torsion.
There are parallels between the imaging of testicular torsion and acute appendicitis. Early intervention is of such importance that clinical concern should override imaging findings. The demonstration of normal blood flow in a testis does not exclude torsion as evidenced by a study where of seven patients with surgically proven torsion, one patient with acute 360° torsion had normal flow on color Doppler study relative to the contralateral side. 2
Treatment is prompt surgical exploration and detorsion. If the pain has lasted less than 4-6 hr, manual detorsion may be attempted. This maneuver is performed by rotating the testis inward (the left testis is rotated clockwise). Successful manual detorsion results in dramatic pain relief. If the testis is explored within 6 hr of torsion, up to 90% of the gonads will survive. Survival decreases rapidly with a delay of more than 6 hr. If the degree of torsion is 360 degrees or less, the testis may have sufficient arterial flow to allow the gonad to survive, even after 24-48 hr. The testis is then fixed in the scrotum with nonabsorbable sutures, termed scrotal orchiopexy, to prevent torsion in the future. The contralateral testis should be fixed in the scrotum because the condition may be bilateral. If the testis appears nonviable, orchiectomy is performed. 3
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