Welcome to another ultrasound-based case, part of the “Ultrasound For The Win” (#US4TW) Case Series. In this peer-reviewed case series, we focus on real clinical cases where bedside ultrasound changed management or aided in diagnoses. In this case, a 22-year-old man presents with acute scrotal pain.
CASE PRESENTATION
A 22-year-old otherwise healthy man presents to the ED with an acute onset of right testicular pain. He states his pain started about 2.5 hours prior to arrival in the ED. He has associated nausea, but no vomiting. He denies any recent sexual activity or trauma. The remainder of history is unremarkable. On exam, he appears to be in moderate distress, and he has exquisite tenderness to palpation and moderate swelling of the right testicle. The left testicle is non-tender and unremarkable.
VITALS
| BP | 119/82 mmHg |
| P | 109bpm |
| RR | 22 breaths/min |
| SpO2 | 99% RA |
| T | 37.2 C |
DIFFERENTIAL DIAGNOSIS
- Epididymitis
- Hematoma
- Hernia
- Hydrocele
- Orchitis
- Mass/Tumor
- Testicular torsion
- Scrotal abscess
- Varicocele
POINT-OF-CARE ULTRASOUND was performed which showed the following:
Figure 1. Ultrasound of the right testicle. No flow is seen with color doppler.
The ultrasound clip of the right testicle with color doppler (figure 1) reveals no flow, concerning for testicular torsion with lack of blood flow to the testicle. Given the emergent nature of the condition, urology was consulted, and the testicle was manually detorsed by the emergency physician using the “open book” technique with relief of symptoms. Immediate repeat point-of-care ultrasound of the right testicle with color doppler is shown below, revealing reperfusion hyperemia. This is commonly seen after a testicle is detorsed.
Figure 2. Repeat ultrasound of the right testicle, post-manual detorsion showing reperfusion hyperemia as visualized with color doppler.
ULTRASOUND IMAGE QUALITY ASSURANCE (QA)
The ultrasound images in this case were obtained using a high-frequency linear probe. A general approach is to have the patient comfortably sitting or laying supine in a frog-leg position. A rolled towel can be draped under the scrotum to elevate and stabilize the testicles. Warm gel should ideally be used for comfort. A tegaderm can be placed over the linear probe to keep the probe clean.
Once the patient is positioned, it is best to start with the non-affected testicle for patient comfort as well as providing a baseline for the ultrasonographer; the gain, depth, and color doppler scale can be adjusted until just enough color doppler flow is obtained with minimal background noise (Tip: Using your ultrasound machine’s “auto calibrate” button will usually suffice to optimize this for you!). The use of color doppler to visualize testicular blood flow has been shown to be highly sensitive (86%) and specific (100%) in aiding in the diagnosis of testicular torsion when assessing for presence or absence of intratesticular blood flow. 1
If you reach the lowest scale using color doppler and are still unable to visualize testicular blood flow, switching to power doppler may help. Power doppler is up to five times more sensitive for low-flow states than color doppler, 2 and is less dependent on angle. A testicle with normal color doppler flow is shown below.
Figure 3. Normal testicular ultrasound. Note the normal homogenous echotexture and normal flow pattern with color doppler.
For Advanced Readers: In addition to simply looking qualitatively at the blood flow with color doppler, a Resistive Index (RI) can be measured. Using Pulsed-Wave Spectral Doppler with the gate positioned over a testicular artery, an arterial waveform is produced. The Resistive Index can then be calculated using the formula:
Most ultrasound machines will be able to calculate this for you. A normal testicular RI is 0.5-0.7 3 ; an RI higher than this suggests an increased resistance to flow which can be concerning for early torsion.
Figure 4. Measurement of Resistive Index of a testicular vessel. Pulsed-Wave Doppler with the gate ( = ) positioned over a testicular vessel produces a waveform from which the peak systolic velocity (SV) and end diastolic velocity (DV) can be measured. In this case, the RI is 0.635 cm/s, which is normal.
As with most point-of-care ultrasound, scan the testicle in two planes, including the epididymis, and assess the echotexture. Once a baseline is obtained from the unaffected testicle, you can move on to the affected testicle in the same manner, using the settings you have just optimized. For testicular torsion, you are looking specifically for lack of blood flow, or a high resistive index.
DISPOSITION AND CASE CONCLUSION
Given the findings of testicular torsion confirmed with bedside ultrasound, urology was emergently consulted, and the patient was taken to the OR for orchiplexy. The testicle was salvaged. The patient has since been discharged and is doing well.
Testicular torsion has an incidence of 1 in 4,000 males, with pubescent boys being most frequently affected. 4 Torsion is a cause of significant morbidity with average testicular salvage rates being low at only 50%. 4 It is often said that “time is testicle”, with signs of testicular hemorrhage and infarction appearing within 2 hours of testicular artery occlusion, and irreversible ischemia after 6 hours. 5 Thus, it is important to diagnose testicular torsion as early as possible to reduce time to definitive surgical management, and have urology consulted as soon as torsion is considered.
Color doppler ultrasonography is considered the imaging mode of choice in patients presenting with acute scrotal pain. Given the time-sensitive nature of testicular emergencies such as testicular torsion, it is extremely valuable for an emergency physician to have the skill to perform point-of-care testicular ultrasonography. This is especially beneficial in smaller community EDs where prompt radiology-performed ultrasonography may not be readily available. An EP-performed point-of-care ultrasound can be performed easily and promptly in patients who present to the ED with acute scrotal pain with high sensitivity (95%) and specificity (94%). 6 As seen in this case, it can aid in the diagnosis of testicular torsion, and can expedite time to definitive surgical management.
TAKE-HOME POINTS
- Testicular ultrasound can aid in the diagnosis of acute scrotal pathology, and is a useful skill for the emergency physician to have.
- Point-of-care testicular ultrasonography by emergency physicians has a high sensitivity (95%) and specificity (94%). 6
- Start with the unaffected testicle to optimize your settings (the auto-calibrate button can help!)
- Resistive Index = (Peak Systolic Velocity-End Diastolic Velocity)/Peak Systolic Velocity. Normal is 0.5-0.7 cm/sec.
- Testicular torsion is a surgical emergency – Call the urologist as soon as it is suspected.
Special thanks to Dr. Chris Moore for permission to use the included ultrasound clips and images!
*Note: All identifying information and certain aspects of the case have been changed to maintain patient confidentiality and protected health information (PHI).
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