For the detection of testicular torsion, the sensitivity and specificity of ultrasonography approaches 100% for experienced sonologists. An ED study of 36 patients with acute testicular pain had a sensitivity of 95% and specificity of 94%, when surgical follow-up and radiology imaging were used as standard.
On ultrasound a testicle appears quite homogeneous in echotexture. When torsion is present signs of edema or necrosis are may be present. Color and spectral doppler are required when evaluating a patient for torsion to evaluate blood flow. Power doppler, a nondirectional version of color doppler, is thought to be more sensitive for detecting blood flow.
If the diagnosis is in doubt due to continued pain or if torsion–detorsion is suspected, performing serial examinations with ultrasound or admission to the OR with urology is needed. Always remember that time is testicle and increasing time equals decreasing salvage rate. At 8 hours the salvage is approximately 75%.
Emergency Ultrasound 2nd ed., ch. 11 Testicular