What is Normal

A normal testicle will be ovoid shaped with a vertical lie. The echogenicity on gray scale US should be uniform and homogonous. You should see the tunica albuginea lining the outside of the testicle as a thin, hyperechoic rim. The mediastinum testis is a hyperechoic band crossing the center of the testicle, best seen in the longitudinal view (Figure 3); however, it may not always be visible, and in the setting of trauma, it can be mistaken for pathology. The epididymis is seen adjacent to the testis and is slightly hypoechoic relative to the testis (figure 4).  In color flow doppler, the testicles should have blood flow equal bilaterally. Look for presence of arterial blood flow in the center of the testicle (Figure 5).

 

Figure 3. Normal testicles in longitudinal view. The arrows are pointing to the mediastinum testis which is a normal finding. The arrowheads are outlining the tunica albuginea [13]

 

Figure 4. Normal testicles in transverse view

 

Figure 5. Color flow doppler of normal testicle in longitudinal view

Video 1: Normal color doppler of the left testicle. Video courtesy of David Kirschner, used with permission.

Stepwise Technique

1. 2D Grey scale assessment: Start in 2D gray scale mode and scan each testicle in both the transverse and longitudinal planes (Figure 2). This can be used to assess testicle size, lie and texture.

** If using the small linear probe, assess each testicle individually and save images to compare—be careful to not change settings on the machine between sides

2.  Dual testicle Comparison: If you have a large linear probe, position the probe in the transverse plane at the inferior scrotum and apply minimal upward pressure to lift both testicles. This allows for direct visualization of both testicles simultaneously to compare size, texture, lie, and doppler flow.

3. Doppler Evaluation: In the longitudinal view, use color doppler to assess flow to the testicles. Start with the unaffected testicle to evaluate the flow on color doppler.  Next, assess the affected testicle to determine whether there is increased, decreased or absent flow in comparison to the unaffected side.

** Add pulsed wave Doppler evaluation of both testicles if required by your local policy.

4. Spermatic Cord Evaluation: In the transverse plane, slide the probe superiorly along the length of the spermatic cord. Use greyscale and color Doppler to assess for abnormal twisting. Store a clip of the spermatic cord, regardless of whether it appears normal or abnormal.

5. Documentation: Be sure to document and store images at each step of the exam, including both the affected and unaffected sides.

 

Figure 2. Ultrasound image acquisition of the testicles in the transverse and longitudinal planes

Indications

• Rule in testicular torsion in acute testicular pain

 

Equipment

• Ultrasound machine
• Probe: high frequency linear probe (ex. 5-12 MHz)
• Ultrasound gel
• Towels for draping, patient positioning, and clean up

 

Patient Positioning

Position the patient supine and support the scrotum with towels. The penis can be positioned dorsally and draped with towels to expose only the testicles

 

Testicular Anatomy Review

 

In a patient with normal anatomy (Figure 1A), the scrotum is divided into left and right by the scrotal septum. Each compartment contains a testis, an epididymis, and the spermatic cord. The testicle is covered by a fibrous capsule called the tunica albuginea. This capsule projects into the testicle to form the mediastinum testis. Testicular seminiferous tubules run through the mediastinum testis and exit the testicle to form the epididymis which continues as the vas deferens. The spermatic cord contains the vas deferens as well as testicular vessels and nerves.  

 

In testicular torsion, the testicle spins, twisting the spermatic cord and causing compression of the blood vessels (Figure 1B), thereby limiting venous outflow and arterial inflow (Figure 1C).  

 

 

Figure 1. A) Normal testicular anatomy. B) Testicular torsion demonstrating torsion of the spermatic cord C) Arterial supply to the testicle  

Introduction

Testicular torsion (TT) is a common urological emergency with the majority of cases occurring in adolescence, making this an important presentation to pediatric emergency departments (EDs). TT accounts for 10-15% of pediatric acute scrotum (1). Testicular torsion typically presents with acute onset, unilateral testicular pain, and may be associated with nausea and vomiting. The differential diagnosis of TT is broad and includes more common diagnoses such as epididymo-orchitis and torsion of the appendix testis (1). 

Cases that are highly suggestive of testicular torsion warrant immediate consultation with urology for de-torsion; however, in cases where the diagnosis is uncertain or at the request of the surgical team, doppler ultrasound is used to confirm the diagnosis prior to surgical intervention. 

 Certain clinical features are highly suggestive of the diagnosis of TT. The Testicular Workup for Ischemia and Suspected Torsion (TWIST) score (Table 1) was developed to help diagnose TT and decrease the use of ultrasound (2,3) . Low TWIST score (0-2) has a sensitivity 98% which allows ruling out TT and high TWIST (5-7) has specificity of 97% which allows ruling in the diagnosis. Ultrasound is helpful to confirm the diagnosis for the intermediate (2-4) risk group (2,4,5). 

 

Table 1. TWIST score for clinical suspicion of testicular torsion. 

Testicular swelling	2 points
Hard testis on palpation	2 points
Absent cremasteric reflex	1 point
High riding testis	1 point
Nausea or vomiting	1 point

 

Delayed diagnosis of TT is associated with loss of testis and infertility. Cases that are highly suggestive of testicular torsion warrant immediate surgical consultation. The European Associatione of Urology 2024 recommendations for pediatric TT include that the clinical decision should be based on physical examination and ultrasound can be used as an adjunct that should not delay definitive care (6). In confirmed cases of TT, early surgical exploration is warranted. 

 

Why PoCUS?

Studies consistently show that the most important factor for testicle viability is the duration of ischemia (7–9). Salvage of the testicle diminishes significantly after 6 hours, making early identification of this condition extremely important for improved patient outcomes (9). The median time from symptom onset to ED presentation for patients with possible TT is 4 hours – leaving only 2 hours for triage, ED physician assessment, work-up, urology consultation and transfer to the operating room to improve chances of testicular viability (7). Delays to definitive care in patients with TT are a preventable cause of orchiectomy in young men (7,10). PoCUS is an easily accessible bedside tool that can be used to expedite care for these patients. It can also help with resource allocation of our radiology performed ultrasounds, especially at centers where this is not readily available 24 hours a day. PoCUS can be used to rule in TT and has been shown to decrease time to OR for testicular torsion and decreased length of stay in ED (10,11). 

 

Testicular PoCUS skills can be acquired rapidly. Competency and skill confidence was achieved by urology and emergency resident following a curriculum which included three audio lectures followed by 1-hour of hands-on practice (12). The test characteristics of PoCUS vs RADUS are demonstrated in Table 2.   

 

Table 2: Test characteristics of radiology performed ultrasound vs. point-of-care ultrasound for testicular torsion (10) 

	Radiology US	Point of Care US
Sensitivity	100%	95%
Specificity	98%	93%
Positive predictive value	83%	46%
Negative predictive value	100%	100%
Median time for performing US	61 minutes	23 minutes

 

 

 

 

 

Author: Jade Seguin, MD, FRCPC

Secondary Author: Michelle Fric, MD, FRCPC

Reviewer(s): Christopher Chan, MD, FRCPC, Mark Bromley, MD, FRCPC, Melanie Willimann, MD, FRCPC, Colin Bell, MD, FRCPC, Omar Damji, MD, FRCPC, Julia Stiz, MSc, RDMS

 

*To continue through to the course, make sure to select the “Mark as Completed” button below.

**To unlock access to the first quiz, make sure to select the “Mark as Completed” button below

References

1. Alrajhi K, Woo MY, Vaillancourt C. Test characteristics of ultrasonography for the detection of pneumothorax: a systematic review and meta-analysis. Chest 2012;141:703-8. doi:10.1378/chest.11-0131.

2. Seow et al. Comparison of Upright Inspiratory and Expieratory Chest Radiographs for Detecting Pneumothoraces. AJR 1996; 166:313-316. doi: 10.2214/ajr.166.2.8553937.

3. Murphy et al. CT and Chest Radiography are Equally Sensitive in the Detection of Pneumothorax After CTGuided Pulmonary Interventional Procedures. AJR 1990;154:45-46. doi: 10.2214/ajr.154.1.2104723.

4. Raimondi et al. Lung Ultrasound for Diagnosing Pneumothorax in the Critically Ill Neonate. J Pediatr 2016;175:74-8. doi:10.1016/j.jpeds.201.04.018

5. Cattarossi et al. Lung Ultrasound Diagnostic Accuracy in Neonatal Pneumothorax. Canad Resp J. 2016. doi 10.1155/2016/6515069

6. Liu et al. Lung ultrasonography to diagnose pneumothorax of the newborn. AJEM 2017;35:1298-1302. doi: 10.1016/j.ajem.2017.04.001.

7. Volpicelli et al. Semi-quantification of pneumothorax volume by lung ultrasound. Int Care Med 2016;40:14607. doi:10.1007/s00134-014-3402-9.

Conclusion

Congratulations on taking the first step towards adopting PoCUS as a part of your practice! The key concepts in this chapter can be revisited regularly to help you understand how to generate and interpret different scans. Orienting yourself to a 2D representation of a 3D object will take some time, so take any opportunity you have to reach for an US probe to hone your skills. Image generation is the most difficult skill to obtain with respect to PoCUS but with a systematic approach you will be able to reliably create high-quality scans that can enhance your clinical decision-making.