[Testicular torsion: diagnosis, differential diagnosis, and treatment in children].

Acute scrotum represents an emergency situation although testicular torsion is present in less than 20% of the cases. Sonography has meanwhile become the definitive modality for diagnosis. Its increasing use before surgical intervention has led to technical improvements in ultrasound diagnostics and critical assessment of ultrasound criteria to exclude testicular torsion as well as standardization of examination procedures. Central arterial and venous perfusion shown to be bilaterally equal on Doppler sonography is the most important criterion for excluding torsion. This article discusses other criteria such as the "resistance index," comparison of parenchymal structure of both testes, evidence for spermatic cord torsion, or differences between the sides in perfusion of the testicular parenchyma and highlights the difficulties involved in partial and intermittent testicular torsion. Alternative investigative methods and the significance of sonography in the differential diagnosis of other underlying causes are addressed. In summary, the combination of interpreting B-mode imaging, color Doppler, and power Doppler sonography and analyzing Doppler flow curves after clinical examination results in successful and conclusive evaluation of the testes in cases of acute scrotum in boys.