Primary Author: Melissa Skaugset, MD, FRCPC

Secondary Author: Julia Stiz MSc, RDMS

Reviewer(s): Melanie Willimann, MD, FRCPC, Dave Kirschner, MD, FRCPC

References

1. Liang T, Metcalfe P, Sevcik W, Noga M. Retrospective review of diagnosis and treatment in children presenting to the pediatric department with acute scrotum. AJR Am J Roentgenol. 2013 May;200(5):W444-9.
2. Barbosa JABA, de Freitas PFS, Carvalho SAD, Coelho AQ, Yorioka MAW, Pereira MWA, et al. Validation of the TWIST score for testicular torsion in adults. Int Urol Nephrol [Internet]. 2021;53(1):7–11. Available from: https://doi.org/10.1007/s11255-020-02618-4
3. Barbosa JA, Tiseo BC, Barayan GA, Rosman BM, Torricelli FCM, Passerotti CC, et al. Development and initial validation of a scoring system to diagnose testicular torsion in children. J Urol. 2013 May;189(5):1859–64.
4. Qin KR, Qu LG. Diagnosing with a TWIST: Systematic Review and Meta-Analysis of a Testicular Torsion Risk Score. J Urol. 2022;208(1):62–70.
5. Choudhury P, Saroya KK, Anand S, Agarwal P, Jain V, Dhua AK, et al. Unjumbling the TWIST score for testicular torsion: systematic review and meta-analysis. Pediatr Surg Int. 2023 Feb;39(1):137.
6. Radmayr CB, Burgu B, Castagnetti M, Dogan H, O’Kelly F. EAU guidelines on paediatric urology 2024. European Association of Urology. 2024. 26–29 p.
7. Chan EP, Wang PZT, Myslik F, Chen H, Dave S. Identifying systems delays in assessment, diagnosis, and operative management for testicular torsion in a single-payer health-care system. J Pediatr Urol [Internet]. 2019;15(3):251.e1-251.e7. Available from: https://doi.org/10.1016/j.jpurol.2019.03.017
8. Mori T, Ihara T, Nomura O. Diagnostic accuracy of point-of-care ultrasound for paediatric testicular torsion: A systematic review and meta-Analysis. Emerg Med J. 2022;40(2):140–6.
9. Ramachandra P, Palazzi KL, Holmes NM, Marietti S. Factors influencing rate of testicular salvage in acute testicular torsion at a tertiary pediatric center. West J Emerg Med. 2015 Jan;16(1):190–4.
10. Park JS, Kim D, Chun MK, Choi SJ, Lee JS, Ryu JM, et al. Implementing Point-of-Care Ultrasound for Acute Scrotal Pain in the Pediatric Emergency Department: Screening Testicular Torsion and Patient Flow Analysis. J Ultrasound Med. 2023;42(12):2757–64.
11. Koppel JH, Patt YS, Berant R. Point-of-Care Ultrasound for the Diagnosis of Pediatric Testicular Torsion: A Retrospective Case Series Analysis. Pediatr Emerg Care. 2023;39(8):623–8.
12. Stringer L, Cocco S, Jiang A, Chan EP, Myslik F, Brahm G, et al. Point-of-care ultrasonography for the diagnosis of testicular torsion: A practical resident curriculum. Can J Surg. 2021;64(2):E191–5.
13. Siegel, M. J. (2019). Pediatric sonography (5th ed.). Wolters Kluwer Health.
14. Shields LB, Daniels MW, Peppas DS, Rosenberg E. Sonography Findings Predict Testicular Viability in Pediatric Patients With Testicular Torsion. Cureus. 2022;14(1):1–7.
15. Afsarlar CE, Cakmakci E, Demir E, Guney G, Komut E, Elizondo R, et al. Novel prognostic grayscale ultrasonographic findings in the testis from a comprehensive analysis of pediatric patients with testicular torsion. J Pediatr Urol. 2019 Oct;15(5):480.e1-480.e7.
16. Dogra VS, Bhatt S, Rubens DJ, Sonographic evaluation of testicular torsion) Ultrasound clin. 2006;1:55-66
17. Cassar, S., Bhatt, S., Paltiel, H.J. and Dogra, V.S. (2008), Role of Spectral Doppler Sonography in the Evaluation of Partial Testicular Torsion. Journal of Ultrasound in Medicine, 27: 1629-1638. https://doi.org/10.7863/jum.2008.27.11.1629
18. McDowall J, Adam A, Gerber L, Enyuma COA, Aigbodion SJ, Buchanan S, et al. The ultrasonographic “whirlpool sign” in testicular torsion: valuable tool or waste of valuable time? A systematic review and meta-analysis. Emerg Radiol. 2018;25(3):281–92.
19. Nene R V., Subramony R, Marcias M, Campbell C, Aminlari A. Real-time Point-of-care Ultrasound for the Diagnosis and Treatment of Testicular Torsion. POCUS J. 2021;6(2):70–2. 19
20. Hsu C Te, Chiu PW, Deanehan JK. Successful Outcome of Manual Testicular Detorsion Using Point-of-Care Ultrasound Guidance: A Clinical Experience. Pediatr Emerg Care. 2023;39(10):813–5.
21. Güneş M, Umul M, Çelik AO, Armaʇan HH, Deʇirmenci B. A novel approach for manual de-torsion of an atypical (outward) testicular torsion with bedside Doppler ultrasonography guidance. Can Urol Assoc J. 2015;9(9–10):E676–8.

Summary

 

• Time is testicle. In cases of testicular torsion, outcomes are improved with detorsion in less than 6 hours from symptom onset
• PoCUS may be used as an adjunct to clinical decision making alongside the TWIST score when the suspicion for TT is intermediate.
• PoCUS should be utilized as a rule-in test for testicular torsion but should never delay surgical consultation or formal ultrasound when clinical suspicion of torsion is high
• The most specific signs for testicular torsion are absent/decreased testicle vascularity and whirlpool sign.

Pitfalls & Limitations

 

• PoCUS can be used to rule IN TT, but should not be used to rule OUT in cases with moderate to high pretest probability
• Partial TT may have preserved color doppler flow. It should be decreased when compared to the contralateral testicle.
• Torsion-detorsion may have either reduced or increased signal (hyperemia) depending on the stage of torsion-detorsion, which can mimic orchitis therefore it is imperative to interpret increased perfusion in the clinical context

 

Due to these limitations, if a patient presents with a high TWIST score and a strong history and physical exam suggestive of torsion, but the ultrasound is inconclusive or normal, maintain a high index of suspicion. Consider arranging a repeat scan in the morning or calling in the sonographer if clinically indicated.

 

Opening the Book: PoCUS Guided Manual Detorsion

Manual detorsion is a non-invasive procedure that emergency physicians can perform at the bedside to reverse the torsion and return blood flow to the testicle. The European Urological Association Pediatric Urology Guideline states that manual detorsion should be attempted in all cases of testicular torsion at the physician’s discretion and can be done without anesthesia. In testicular torsion, the testis is typically rotated inwards. Therefore, manual detorsion is typically performed by manually rotating the testicle outward, from medial to lateral. This results in reperfusion in about ⅓ of cases. There are multiple factors which influence success rates for manual detorsion including the degree of torsion and the direction of rotation (19). If you are trying to detort in the wrong direction or you do not rotate enough, vascular flow will not be restored.

PoCUS can be used to help identify direction of rotation of the torsion to help guide the counter-direction for manual detorsion (20). If you identify the whirlpool sign, you can determine the direction of rotation (Figure 14) (20,21). Ultrasound can also be used to assess for reperfusion of blood flow on color doppler and resolution of whirlpool sign. Additionally, the patient should have an abrupt improvement in pain with restoration of blood flow which can be confirmed by direct visualization on ultrasound.

Figure 14. Using the whirlpool sign (B,C) to identify direction of manual detorsion resulting in return of blood flow on color doppler (D) (20).

What is NOT Normal

 

2D Findings: Testicular orientation, volume and texture

Orientation: In testicular torsion, the affected testicle often lies horizontally

Volume: In acute torsion, the testicle is enlarged with increased volume (Video 2). In chronic or missed torsion the testicle undergoes atrophy, leading to a decrease in volume. Unilateral increased volume of the testicle should raise suspicion for partial torsion or torsion-detorsion in the right clinical context but may also be seen in orchitis.

Texture: Testicular heterogeneity (figure 6) is typically a later finding and associated with worse outcomes, including non-viable testis (14). Testicular fragmentation and patching can be seen once the testicle becomes necrotic and increases the risk of testicular loss (figure 7)(15).

Figure 6. Heterogenous echogenicity of enlarged testicle

Figure 7. Testicular fragmentation (a,b) and patching (c,d)

 

 

Color Doppler

Absent testicular flow (Figure 8A)

Absence of doppler flow is highly predictive of TT, with 97% positive predictive value and 75% specificity for TT (7). If there is absence of flow, the case should be treated emergently as TT.

Decreased testicular flow (Figure 8B)

Early or partial testicular torsion (usually <360 degrees) may have preserved arterial flow since the arterial flow is impaired, but not completely obstructed. The color doppler signal may be decreased compared to the other side. Radiology ultrasound includes evaluation of arterial and venous waveform using spectral doppler to confirm this diagnosis.

Increased Blood Flow (Figure 8C)

In cases of torsion-detorsion, rebound reperfusion can result in hyperemia of the affected testicle. It may mimic the sonographic appearing of orchitis which may also have increased color flow. It is imperative to interpret increased perfusion in the clinical context.

Figure 8. Abnormal testicular flow of the affected testicular (blue star) in the transverse plane A) Absent flow B) Decreased flow C) Increased flow on color doppler [15]

 

Figure 9. A) Heterogenous echogenicity of enlarged testicle and B) Heterogenous testicle with absent blood flow [15]

 

Video 2. Testicular torsion with absent flow and increased volume to left testicle

Spectral Doppler

Although not routinely used in PoCUS, spectral Doppler is commonly employed in Radiology when assessing for testicular torsion. Using spectral doppler in addition to color doppler to confirm torsion has been associated with a higher PPVs in predicting testicular torsion (7)

Pulsed wave spectral doppler can be used to confirm the presence of arterial and venous flow in the testicle in addition to color doppler since color doppler can be subject to motion artefact (16), but obtaining spectral waveforms can be difficult due to size of vessels and angle correction

Normal Spectral Doppler:

With spectral doppler, arterial wave forms are pulsatile with distinct systolic and diastolic phases. Systolic phases begin with a sharp upstroke followed by a diastolic component that varies with resistance. Venous waveforms are continuous or monophasic (no systolic or diastolic peaks) and generally have lower velocity and some respiratory variation.

Normal arterial flow within the testicle will be pulsatile and exhibit high flow, low resistance, waveforms (16,17) (figure 10), whereas venous flow will exhibit low-velocity, continuous waveforms with minimal pulsatility (figure 11).

Figure 10: Arterial spectral doppler of the testicle

Figure 11: Venous testicular spectral doppler

 

Abnormal Spectral Doppler: In early or complete torsion, the arterial waveforms will be absent or diminished. When comparing to the non-affected testicle, you may observe blunted waveforms with decreased flow velocity in the affected testicle and higher velocity flows in the non-affected testicle (16,17). Venous waveforms will be absent (17).

Figure 12: Torsed testicle with blunted arterial waveform. Image courtesy of Colin Bell, used with permission.

 

Secondary Findings:

Whirlpool Sign:The whirlpool sign is an US image of the spermatic cord above the testicle displaying a spiral with concentric circles. The finding is due to visualization of the twisted spermatic cord. A metanalysis looking at radiology performed US in patients over 3 months old with TT found a pooled sensitivity of 0.92 and pooled specificity of 0.99 for presence of whirlpool sign (18). The sensitivity of whirlpool sign is low in neonates < 30 days (18).

It’s important to note that this sign may not always be present. An important differential to consider is an epididymal abscess, although rare, can also present with a similar appearance.

Video 3. Whirlpool sign

 

Epidydimal Swelling: (Figure 13A)

Secondary to the inflammatory process within the scrotum, the ipsilateral epidydimis may become swollen with testicular torsion.

Reactive Hydrocele: (Figure 13B)

Presence of hydrocele is nonspecific to testicular torsion but can be frequently encountered during ultrasound examination of the acute scrotum. The hydrocele fluid is anechoic and surrounds the testicle.

 

Figure 13. Testicular ultrasound in the longitudinal plane demonstrating A) enlarged epidydimal head (blue star) and reactive hydrocele (red star)

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