What is the significance of an ultrasound of the scrotum showing no hyperemia (increased blood flow)?

From the Guidelines

The absence of hyperemia on a scrotal ultrasound is a reassuring finding, but it does not completely rule out testicular torsion or other scrotal disorders, and clinical correlation is necessary for accurate diagnosis. According to the American College of Radiology Appropriateness Criteria 1, ultrasound is the established first-line imaging modality for acute scrotal disease, and high-resolution grayscale and color Doppler US can help differentiate scrotal emergencies. The sensitivity and specificity of color Doppler US for the detection of testicular torsion are variable, with reports ranging from 69% to 96.8% and 87% to 100%, respectively 1.

Key Considerations

• The absence of hyperemia on ultrasound does not necessarily indicate normal testicular perfusion, as some cases of testicular torsion may present with normal or decreased blood flow 1.
• Other ultrasound findings, such as an enlarged heterogeneous testis, ipsilateral hydrocele, skin thickening, and the "whirlpool sign" of a twisted spermatic cord, should be evaluated in conjunction with the absence of hyperemia 1.
• Clinical correlation is essential, as the presence of fever, waxing and waning pain, and laboratory markers for infection can help distinguish between testicular torsion and epididymoorchitis 1.

Next Steps

• If scrotal pain or swelling persists despite the absence of hyperemia on ultrasound, further evaluation may be necessary to determine the underlying cause 1.
• A thorough physical examination, medical history, and possibly other diagnostic tests should be considered to determine the appropriate diagnosis and treatment plan 1.

From the Research

Ultrasound Scrotum Findings

• The absence of hyperemia on ultrasound scrotum findings can be significant in diagnosing scrotal diseases 2.
• Hyperemia is typically characterized by increased blood flow, which can be detected using Doppler sonography 2.
• In cases of inflammation, resistive indexes (RI) are lower due to hyperemia, with average RI values of 0.454 for intratesticular hyperemia and 0.575 for supratesticular hyperemia 2.
• The absence of hyperemia may suggest alternative diagnoses, such as testicular torsion, which is characterized by reduced or absent blood flow 2.

Diagnostic Considerations

• Ultrasound is the imaging modality of choice for evaluating scrotal diseases due to its high resolution, Doppler capabilities, and lack of ionizing radiation 3, 4, 5.
• The radiologist's knowledge of sonographic features, combined with the patient's symptoms and physical examination, allows for accurate diagnosis of scrotal pathology 4.
• Differentiating between acute epididymitis/epididymo-orchitis and testicular torsion is possible using ultrasound, guiding appropriate medical or surgical management 3, 5.

Ultrasound Techniques

• Doppler sonography is a reliable technique for diagnosing acute scrotum and can decrease the number of unnecessary surgeries 2.
• Conventional sonography can also be used to evaluate scrotal diseases, but Doppler sonography is superior for differential diagnosis 2.
• Ultrasound examination should be performed as soon as possible in emergency conditions to ensure fast diagnosis and treatment 6.