Diagnostic imaging of patients with acute scrotal pain

Author: Thomas J. Barloon, Daniel Kahn
Date: April, 1996

Acute scrotal pain is an important diagnostic problem because of the serious consequences of delayed diagnosis. A complete history and physical examination may clearly indicate the cause of scrotal pain and direct clinical management (Tables 1 and 2). However, signs and symptoms in he individual patient may be confusing and diagnostic imaging can be a useful adjunct to appropriate management.[1-5]


Whether the testis is viable or not, exploration of the scrotal sac is indicated. If a viable testicle is identified, orchiopexy is necessary to reduce the torsion and correct the bell-clapper deformity to prevent recurrences. Exploration and orchiopexy of the contralateral side is also indicated to prevent future torsion. In patients with a missed diagnosis of testicular torsion, the gray-scale ultrasound shows a small shrunken echogenic testicle without blood flow, although blood flow within the wall of the testicle may be present.


Complete testicular evaluation by nuclear medicine studies includes a radionuclide angiogram to assess the arterial flow and static images to assess perfusion at the tissue level.[1] A minimum of 5 mCi of technetium-99m pertechnetate is administered intravenously in children and a minimum of 20 mCi is used in adults. A radionuclide angiogram (five to 10 frames, 5 seconds each) is obtained, with static images immediately after the flow study. Serial images for 10 minutes and a delayed image at 20 minutes are also acquired (Figure 3).[17]

Surface markers that identify the location of each testis are correlated with the angiographic flow and static images. It is critical that the patient is properly positioned: the median raphe must be centered, and the penis taped over the pubis. The camera is centered over the penilescrotal junction, and the location of each testis should be clearly determined and labeled on the images.


The normal radionuclide angiogram of the testes shows symmetrical perfusion in the iliac and femoral arteries. In men with acute torsion, static images show a photondeficient area in the involved hemiscrotum, which represents the ischemic testis (Figure 4).[1,17]

In patients with subacute torsion, i.e., seven to 24 hours after the onset of symptoms, the radionuclide angiogram may show increased perfusion to the peritesticular tissue and the static images may show a "halolike" rim surrounding a relatively photon-deficient center. In the late phase of testicular torsion, i.e., more than 24 hours after the onset of symptoms, there is often increased flow in the pudendal vessels and a moderate-to-marked increase activity m the perites-ticular ("halo") region surrounding the photon-deficient necrotic testis (Figure 5).


Compared with testicular torsion, acute epidymitis or epididymo-orchitis, usually occurs in older men.[10] In patients with epididymitis or epididymo-orchitis, the testis demonstrates increased flow through the testicular and deferential arteries on the radionuclide angiogram.[17] The static images show increased activity in the affected hemiscrotum.

In patients with complicated epididymo-orchitis, the static images may demonstrate a pattern similar to the late phase of testicular torsion. Increased activity is demonstrated on the flow study, and delayed images may show a central photon-deficient area because of abscess formation. Although abscess formation is most common in patients with inadequately treated epididymo-orchitis, abscesses can also occur in undiagnosed testicular torsion, with necrotic tumors and in hematomas that have become infected. Surgical drainage is indicated for all scrotal abscesses.

Final Comment

Accurate evaluation of acute scrotal pain is important. A careful history and physical examination usually provides sufficient information to differentiate testicular torsion from epididymo-orchitis. However, when the history and clinical findings are equivocal, diagnostic imaging is usually able to differentiate testicular torsion, which is a surgical emergency, from epididymo-orchitis, which can be treated with antibiotics. Both color Doppler and nuclear medicine techniques provide similar information. Table 5 summarizes the findings of these imaging techniques.


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