Ultrasound is the best initial test
Testicular torsion and acute epididymoorchitis are the most common causes of an acute scrotum.3 Patients with an acute scrotum require an urgent ultrasound to exclude pathology that requires immediate surgery (TABLES 1 AND 2).1 Although clinical exam identifies almost all cases of torsion, a few cases are missed.4 In a study of 209 emergency scrotal explorations, clinical exam by general practitioners and surgeons correctly diagnosed only 92.5% and 94% of testicular torsion cases, respectively, compared with the surgical diagnosis.4
In another study, which used surgery as the diagnostic gold standard, color Doppler ultrasound had a sensitivity of 93.5% for the diagnosis of testicular torsion;5 this has led some to say the combination of both clinical exam and ultrasound should be used to determine the need for surgery.1 However, this combination has not been thoroughly evaluated by researchers, and the best evidence shows that physician exam is essentially the same as color Doppler ultrasound for diagnosing testicular torsion. If torsion cannot be reliably excluded, emergent surgical exploration is mandatory.4
For patients who have a nonacute scrotal mass, ultrasound is often indicated to distinguish intratesticular from extratesticular masses.1 Although testicular neoplasm is relatively rare, it is a concern for patients with non-painful masses. Fortunately, false-negative scrotal ultrasounds are rare. In a small study comparing clinical exam with ultrasound for diagnosis of testicular tumor, the negative predictive value of ultrasound was 100%.6
Although ultrasound has high sensitivity for detection of testicular neoplasm, it cannot differentiate benign from malignant tumors.2 Additionally, ultrasound sometimes fails to differentiate a neoplastic process from a complication of an infection such as an abscess. In those instances, a repeat ultrasound is suggested after antibiotic administration to ensure resolution of the mass.2
When ultrasound is inconclusive, MRI may be helpful
When clinical and ultrasound findings are inconclusive, MRI may help deter-mine a diagnosis. For example, MRI can help distinguish inflammation or abscess from neoplasm, thus preventing a patient from undergoing unnecessary surgical intervention.2,7 If testicular neoplasm cannot be excluded based on clinical and radiographic findings, surgery is indicated.1
Recommendations from others
Few current evidence-based recommendations exist on the approach to patients with scrotal masses. The National Collaborating Centre for Primary Care (UK) suggests an urgent ultrasound when a scrotal mass does not transilluminate or when the examiner cannot distinguish the body of the testis.8