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.
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.
- Testicular torsion
- Scrotal abscess
POINT-OF-CARE ULTRASOUND was performed which showed the following:
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.
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.
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.
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.
- 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).
I agree with Dr. Coffey, your description of the case itself is darn near perfect. I wouldn\'t change it at all.
What I am confused by, and forgive me - by comparison to you I\'m an ultrasound novice, but I don\'t understand this discussion of the resistive index at all. What I love about the case is the obvious and almost easy diagnosis with bedside ultrasound. There is no flow and then an example of when there is flow, easy.
But now this discussion of resistive index - I\'m left not sure of how or when to use it. Could you clarify (for a neophyte) or cut if not really needed by the non US fellow.
Dr. Mell: Thank you for the feedback on the case!
Great point. Resistive index is not absolutely necessary for this study, and I\'ve added an \"advanced\" header. I do think the concept of RI is helpful to know, as it is used in other areas of point-of-care ultrasound. Even if not performed by the EP, I hope it will at least demystify radiology reports of these studies, which will include the RI.
Expert Peer Review
Great Case. Your description is just about perfect so I don\'t have much to add, only a couple of minor observations:
- When I first read the title, \"22M with scrotal pain\" I thought it was going to be a pediatric case/ 22 month old. Maybe 22 y/o M would work, but merely a semantic point.
- I noticed that your color scale was 15 cm/s on the initial image showing no flow, then 10 cm/s in the post reduction image. This could represent a pitfall for some people because its possible that the scale in the first image was simply not optimized/low enough to pick up the flow, but I think you did such an excellent job of describing the proper technique for optimizing and comparing to the normal side that readers will understand. If you have a clip of the non affected side showing flow at the same scale that might be helpful for side by side comparison, but if not I think you\'ve presented the case beautifully as it stands.
Drake: Thanks again for your feedback!
Yes, the \"before\" and \"after\" images used slightly different scales, but as you mentioned, hopefully it is clear in the QA portion that the same scale should ideally be used so that a better comparison can be made. Also of note, both testicles can be compared together in the same clip with a \"spectacle view\".
Also agreed that a clip of the non-affected testicle in the same patient would be ideal, but it\'s unfortunately not available, so I had to substitute another normal testicular scan for Fig. 3.
Expert Peer Review
What a fantastic case Jeff. Agree with Drake and Howie’s comments. Makes this application seem achievable for the non super user emergency physician sonographer. A few additional comments and queries:
- I know this is all about ultrasound; however I am curious:
- On physical examination, was there an abnormal lie to the affected testicle?
- Was the cremasteric reflex present? The reflex is usually absent in patients with testicular torsion in contrast to those with epididymitis.
- Figure 1 shows a nice reactive hydrocele, which may be a later sign (12 to 24 hours) in patients with testicular torsion.
- I would consider obtaining the straddle view when imaging patients with testicular complaints. Allows the health care provider to compare the affected and unaffected sides simultaneously. I have provided an example:
- In this video, there is an obvious difference in the size of the affected left testicle and in the heterogeneous echogenicity. This patient had left testicular torsion.
- The sensitivity and specificity rates for emergency physician performed ultrasound you cite are impressive. Do you know if the sonographers in this study were super-users or the more typical emergency medicine residency graduate?
Thank you Dr. Lewiss for your Expert Peer Review on the case!
- I believe both testicles had a normal vertical lie, however I don’t think there was a cremasteric reflex on the affected side.
- Great point, a saddle view (or “spectacle view”) with both testicles aligned side-by-side is a great way to make a more direct comparison. This is an awesome clip that clearly demonstrates the difference between the normal and torsed testicle.
- Great question, Resa. The study was done at an urban ED with an EM residency program and ultrasound fellowship program. The EPs that they included in the study included both residents and attendings, with no prior training in performing testicular ultrasound studies.
Thanks again for your contribution to the US4TW case series!