Bedside testicular sonography may assist with the diagnosis and treatment of any patient presenting with acute testicular pain. It can be performed within minutes of arrival and may save time in the diagnosis and treatment of testicular emergencies. It is noninvasive and emergency physicians have been shown to accurately diagnose patients with acute testicular pain using ultrasound.
Testicular torsion and rupture are true surgical emergencies and ultrasound is the diagnostic test of choice for both conditions. Ultrasound may also reveal less acute causes of testicular pain, such as torsion of a testicular appendage, epididymitis, orchitis, hydrocele, and varicocele. These conditions represent the vast majority of cases of nontraumatic testicular pain presenting to the acute care setting.
Bedside ultrasound evaluation of the testes may be performed in:
- The patient with nontraumatic testicular pain, swelling, or mass
- The patient with posttraumatic testicular pain, swelling, or tenderness
- The patient with complaints of penile discharge and found to have testicular tenderness on physical exam
Linear Probe with a Frequency of 7.5–10 MHz
The testes are superficial structures; therefore, probes with higher frequencies that provide better resolution are preferred.
Color-flow Doppler helps to detect the presence and direction of blood flow within the testes. By convention, the color is blue when blood is traveling away from the probe and red when it is flowing toward the probe. The color does not necessarily indicate arterial or venous flow, which must be determined by the character of the flow. The Doppler gain can be increased as needed in order to improve the sensitivity and to detect lower flow states. The pulse repetition frequency (PRF) or "scale" can also be lowered to increase Doppler sensitivity. The sonographer must keep in mind that decreasing the PRF or increasing the gain too much may create unwanted artifact that will erroneously appear as color flow across the testes and can result in a false-negative scan. In contrast, increasing the PRF or decreasing the gain too much (both of which lower sensitivity for flow) may miss blood flow that is actually present, resulting in a false-positive interpretation.
Power Doppler detects the presence of blood flow only without regard to direction. It appears as shades of red depending on the volume of flow. It is more sensitive and less angle-dependent than color-flow Doppler at picking up low-flow states, and therefore is useful for structures such as the testes. But, due to its increased sensitivity, it is also more prone to motion artifact. The sonographer must be careful not to interpret this color artifact as a false-negative study.
Pulse-Wave Doppler and Resistive Index
Pulse wave is a form of spectral Doppler that calculates flow velocity over time and produces a graphic waveform. Blood flow velocities are important ...