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Testicular Torsion

Sandra L Mondro, MD
J Stevan Nagel, MD

January 31, 1995

Presentation

A 38-year-old man presented with two days of right testicular swelling. No history of trauma or systemic illness was elicited.

Imaging Technique

Radionuclide testicular scintigraphy performed with intravenous injection of 10 mCi of technetium-99m pertechnetate.

Imaging Findings

Ultrasonography
Radionuclide scintigraphy

Ultrasound demonstrates an enlarged, heterogeneous right testicle. No loops of peristalsing bowel are present. Doppler examination of the right testicle showed absent flow in the testicle itself but with a small amount of peritesticular flow present. The left scrotal contents were normal.

Radionuclide testicular flow study showed increased tracer accumulation to the right scrotum. Static scintigraphic imaging demonstrates persistent increased uptake (arrow) with a central area of photopenia.

Differential Diagnosis

The ultrasound findings could represent testicular infarction, secondary to torsion or severe infection. An underlying neoplasm, either primary or metastatic, could also have led to torsion with subsequent infarction. In light of a history of trauma, a testicular contusion or fracture may also appear heterogeneous sonographically.

The characteristic bull's-eye or donut sign on the radionuclide study is most consistent with a missed or late phase torsion. A scrotal abscess could also show this pattern.

The radionuclide scintigraphy finding of photopenia within the scrotum can occur with tumor, spermatocele, hydrocele, and hematoma.

Diagnosis

testicular torsion

Discussion

When clinical evaluation alone does not permit a confident diagnosis of epidymitis, orchitis, torsion, post-traumatic injury or less common disorders, evaluation with ultrasound and/or radionuclide imaging is often essential. The sensitivities of the two modalities are virtually the same. The most readily available study should be performed, given the emergent nature of the diagnosis of acute testicular torsion. Prompt surgical intervention leads to a higher salvage rate and is optimal less than four hours post event. Between 4 and 10 hours, the chance of salvaging an affected testis becomes more remote. After 10 hours, most testes are not viable. Although the likelihood of infarction increases over time, some patients with mild degrees of torsion will have viable testes despite delays in intervention.

Color Doppler sonography is almost always abnormal in patients with acute testicular torsion. Proper adjustment of technical parameters is critical and can be confirmed with readily detectable flow in the contralateral testicle.

The increased tracer accumulation on the radionuclide study in a ring-like, donut configuration is secondary to hyperemia from the pudendal blood supply to the scrotal sac.

Torsion occurs when the testicle twists on the spermatic cord, occluding its blood supply from the testicular artery. Predisposed are those with a congenital bell-clapper deformity, in which laxity permits rotation. Because of bilaterality in 50% of patients, prophylactic orchiopexy is often performed on the uninvolved testicle.

References

1. Palmer EL. Practical nuclear medicine. Philadelphia: WB Saunders, 1992.

2. Rumack CM. Diagnostic ultrasound. St Louis: Mosby Year Book, 1991.

3. Lawson TL (section chairman). ACR diagnostic ultrasonography test and syllabus, 2nd series. 1994.

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