Approach Considerations
If testicular torsion is clinically suggested, perform immediate surgical exploration, regardless of laboratory studies, because a negative finding upon exploration of the scrotum is more acceptable than the loss of a salvageable testis.
Laboratory tests are unlikely to be of consequence, as no single test has high sensitivity or specificity in diagnosing testicular torsion. However, when there is a strong suspicion of an alternative diagnosis, laboratory tests may be of some use.
Imaging studies usually are not necessary. Ordering them wastes valuable time when the definitive treatment is emergent urologic consultation for surgical management. However, imaging studies (eg, ultrasonography, nuclear scans) may be useful when a low suspicion of testicular torsion exists.
The TWIST (Testicular Workup for Ischemia and Suspected Torsion) scoring system was developed for the purpose of determining the risk of testicular torsion on clinical grounds, thus decreasing the indication for ultrasound. [20] TWIST has been validated when scored by nonurological nonphysician providers as well as urologists. [21] TWIST consists of the following urological history and physical examination parameters:
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Testis swelling (2 points)
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Hard testis (2)
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Absent cremasteric reflex (1)
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Nausea/vomiting (1)
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High-riding testis (1)
TWIST scores and risk groups are as follows:
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0-2 points - Low risk
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3-4 points - Intermediate risk
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5-7 points - High risk
TWIST has shown 100% negative predictive value when scored by a urologist, using a cutoff value of 2 to identify low-risk patients, and when scored by trained emergency medical technicians (EMTs) using a cutoff of 0 in children. [21, 20] Cutoff values of 5 (scored by a urologist) and 6 (EMTs) have been used to identify high-risk patients. Ultrasound evaluation is indicated for intermediate-risk patients; low-risk patients do not require ultrasound to rule out torsion, and patients at high risk can proceed directly to surgery, with more than 50% avoiding ultrasound. [21]
Urinalysis
If the patient does not show clinical evidence of testicular torsion, a urinalysis and culture may help exclude urinary tract infection and epididymitis as the etiology of the scrotal complaints.
Urinalysis results are usually normal in testicular torsion. The presence of white blood cells (WBCs) can be observed in as many as 30% of patients who have torsion; therefore, do not rely on the presence of WBCs to exclude the diagnosis.
Blood Studies
The complete blood count can be normal. However, the WBC count is elevated in as many as 60% of patients who have torsion.
Mean platelet volume (MPV) has been suggested as a source of diagnostic and prognostic information, with some small studies reporting a higher likelihood of testicular torsion and a greater risk of postoperative testicular atrophy in patients with higher MPVs. [22, 23] However, those studies have proposed different cut-off values for MPV, and other studies have reported conflicting information. [24]
Elevation in acute-phase proteins (ie, C-reactive protein [CRP]) has been postulated as a diagnostic aid in differentiating inflammatory causes of acute scrotal pain (eg, epididymitis) from noninflammatory causes (eg, testicular torsion). [25] However, sample sizes in these studies have been too small to support using CRP as a diagnostic adjunct to definitively rule out testicular torsion.
Ultrasonography
Testicular torsion is a clinical diagnosis. If the history and physical examination strongly suggest testicular torsion, the patient should go directly to surgery without delaying to perform imaging studies.
When a low suspicion of testicular torsion exists, color Doppler and power Doppler ultrasonography can be used to demonstrate arterial blood flow to the testicle while providing information about scrotal anatomy and other testicular disorders. (For images, see Testicular Torsion Imaging.)
Plain Doppler ultrasonography is less accurate than color Doppler in assessing testicular blood flow. In fact, early in the course of testicular torsion, gray-scale ultrasonographic examination may be absolutely normal.
Ultrasonographic findings suggestive of acute testicular torsion include the following [26] :
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Absent or decreased blood flow in the affected testicle
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Decreased flow velocity in the intratesticular arteries
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Increased resistive indices in the intratesticular arteries
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Hypervascularity with a low resistance flow pattern (after partial torsion-detorsion)
The sensitivity of color Doppler examination with newer ultrasonography equipment in detecting acute testicular torsion in children is 90-100%, with the specificity of technically adequate studies being essentially 100%. [27] Other studies have suggested that color Doppler ultrasonography was only 86% sensitive, 100% specific, and 97% accurate in the diagnosis of torsion and ischemia in the painful scrotum. [28]
A 3-year study demonstrated that Doppler ultrasonography had 94% sensitivity, 96% specificity, 95.5% accuracy, 89.4% positive predictive value, and 98% negative predictive value. [29]
The detection of a color or power Doppler signal in a patient presenting with the clinical findings suggestive of testicular torsion does not absolutely exclude torsion. Clinical correlation should be incorporated in the evaluation of acute scrotum because color Doppler ultrasonography is not 100% sensitive. [30]
Spectral and color flow Doppler sonography has also been used to evaluate for partial testicular torsion. Variability of the Doppler waveform when compared with the contralateral testicle and reversal of diastolic blood flow are indirect clues that aid in the diagnosis of partial testicular torsion. [31]
Some smaller studies have evaluated the accuracy of emergency medicine physicians in performing bedside ultrasonography to evaluate for testicular torsion. While these studies have had generally favorable outcomes, diagnostic accuracy is always operator and institution dependent. [32, 33]
A study of the use of contrast-enhanced ultrasonography demonstrated no advantage of this modality over Doppler ultrasonography in the evaluation of the acute scrotum. Contrast-enhanced ultrasonography can, however, be used as a supplement to traditional Doppler sonography when the diagnosis is uncertain and following appropriate clinical and radiographic evaluation. [34]
In a study of 104 adolescent boys, Boettcher et al found that ultrasound predictors alone were not able to identify all cases of testicular torsion. However, clinical features (pain lasting less than 24 hours, nausea and/or vomiting, abnormal cremasteric reflex, and high position of the testis) were predictive with no false positives reported, thus reducing the negative exploration rate by over 55%. Because scrotal ultrasonography is unpleasant in these cases, Boettcher and colleagues recommend that the procedure be used for diagnosis only in patients who lack the clinical features of testicular torsion. [35]
In a study of 342 patients who presented to the emergency department with acute scrotum pain, Liang and colleagues reported no false-negative findings but a 2.6% false-positive rate on ultrasounds performed to assess for testicular torsion. High rates of the clinical features of sudden-onset scrotal pain (88%), abnormal position of testis (86%), and absent cremasteric reflex (91%) were also reported in the patients with testicular torsion. The investigators concluded that color Doppler ultrasound was accurate and sensitive for diagnosis of torsion.z [36]
Altinkilic et al provided further evidence that routine surgical exploration is unnecessary in patients with symptoms of testicular torsion and a normal color-coded duplex sonography scan. In their prospective study of 236 patients with clinical suspicion of testicular torsion, the sensitivity, specificity, and positive and negative predictive values of color coded duplex sonography were 100%, 75.2%, 80.4%, and 100%, respectively. [37]
In a review of 155 surgical explorations for acute scrotal pain, Nason el al reported rates of 96.9%, 88.9%, 96.9% and 89% for sensitivity, specificity, and positive predictive value and negative predictive value, respectively, for Doppler ultrasound used to assess testicular torsion. [38]
McDowall et al reported that the whirlpool sign—a spiral-like pattern seen on assessment of the spermatic cord, using standard high-resolution ultrasonography and/or color Doppler sonography—is a definitive sign for testicular torsion in pediatric and adult patients, but has a limited role in neonates. In their meta-analysis, the whirlpool sign had a pooled sensitivity and specificity of 0.73 (95% CI, 0.65-0.79) and 0.99 (95% CI, 0.92-0.99), respectively. Removal of neonates increased the pooled sensitivity to 0.92 (95% confidence interval [CI], 0.70-0.98) while the pooled specificity remained almost unchanged. [39]
Magnetic Resonance Imaging
Small studies to date suggest that magnetic resonance imaging (MRI), particularly when performed with contrast enhancement, is highly accurate in the diagnosis of testicular torsion, particularly when torsion knot or whirlpool patterns are evident.
As a second-line imaging option, MRI has been utilized to diagnosis incomplete or delayed torsion. It is also useful in differentiating between scrotal abscess and testicular torsion. However, the use of MRI is limited because it is not always immediately available in urgent settings. [40]
Dynamic contrast-enhanced MRI has also demonstrated accuracy. [41] The clinical utility of these studies, however, remains to be elucidated.
Radionuclide Scans
If the diagnosis is equivocal, radionuclide scan of the testicles can be helpful to assess blood flow and to differentiate torsion from other conditions. (For images, see Testicular Torsion Imaging.) These studies should preferably be ordered once urologic consultation has been completed and only for equivocal presentations.
Scan results are abnormal in torsion when they demonstrate decreased uptake in the affected testicle, suggesting no blood flow to that side. Radionuclide scans have a sensitivity of 90-100% in detecting testicular blood flow.
Near-Infrared Spectroscopy
Near-infrared spectroscopy (NIRS) is an emerging tool to assess testicular torsion. It can measure oxygen saturation 3-4 cm deep in the skin, is rapid (lasting 20 seconds), and is noninvasive. Aydogdu et al performed a small prospective study evaluating 16 adult patients with testicular torsion and found NIRS to be 100% sensitive and specific for torsion when compared with the contralateral testis. More studies are needed confirmation before this modality becomes available for clinical use. [42]
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Testicular torsion: (A) extravaginal; (B) intravaginal.
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A 17-year-old adolescent boy with a 72-hour history of scrotal pain.
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Intraoperative findings in testicular torsion.
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Transverse power Doppler image of both testes illustrates an enlarged, avascular left testicle.
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Testicular torsion. Transverse color Doppler image of the left groin illustrates an undescended testicle without flow.
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Example of scrotal appearance in testicular torsion.
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Extravaginal torsion in a newborn.
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Intravaginal torsion in a child.
