Date: January 31st, 2018

Reference: Frohlich LC, et al. Prospective validation of clinical score for males presenting with an acute scrotum. AEM Dec 2017.

Guest Skeptic: Dr. Melissa Langhan is an Associate Professor of Pediatric Emergency Medicine at Yale University in New Haven, CT. Melissa is passionate about clinical and translational research and focuses most of her work on the use of capnography or end-tidal carbon dioxide monitoring. In her spare time, Melissa also enjoys being the fellowship director to an amazing group of PEM trainees.   

Case: Brian is a 14-year-old male who presents to the emergency department (ED) complaining of acute onset testicular pain. He has vomited twice, but there is no history of any fever or trauma. On examination, you find a firm, swollen right testicle, and the cremasteric reflex is notably absent on that side. Your index of suspicion for testicular torsion is high. Might his examination be enough to convince the urologists to take him straight to the operating room without a preceding diagnostic ultrasound?

Background: Acute onset testicular pain can be caused by a variety of etiologies from testicular torsion to epididymitis to traumatic hematomas. Among these, testicular torsion is a time-sensitive diagnosis as this involves loss of or reduced blood supply to the testicle, which can lead to ischemia. Prompt surgical intervention greatly increases the rate of testicular salvage. Time is testis.

Clinical signs of torsion are not always straight forward or specific for this diagnosis. Ultrasound imaging of the scrotum is the gold standard for diagnosis of testicular torsion, however can lead to delays in definitive care.

The Testicular Workup for Ischemia and Suspected Torsion score, or TWIST score, was developed to risk stratify patients under the age of 18 years with an acute scrotum.

The TWIST score ranges from 0-7 and is comprised of 5 components from the history and physical examination:

  • Testicular swelling (2 points)
  • Hard testicle (2 point)
  • Absent cremasteric reflex (1 points)
  • Nausea or vomiting (1 point)
  • High riding testicle (1 point).

While it has been previously validated by urologists and emergency medical personnel, it has not been validated among Emergency Department physicians.

Clinical Question: Can the TWIST score risk stratify pediatric patients presenting with acute scrotal pain and reduce the time to surgical intervention by eliminating the need for ultrasound diagnosis?

Reference: Frohlich LC, et al. Prospective validation of clinical score for males presenting with an acute scrotum. AEM Dec 2017.

  • Population: Patients aged 3 months to 18 years-of-age presenting to the ED with a chief complaint of testicular pain or swelling.
    • Exclusions: Pain due to trauma, symptoms for greater than one-week, previous diagnosis of testicular torsion or testicular disease, imaging already obtained.
  • Predictors: TWIST Score
  • Criterion Standard: A final diagnosis of testicular torsion confirmed by surgical exploration, including patients diagnosed with intermittent testicular torsion.
  • Outcome:
    • Primary Outcome: Diagnostic performance of the TWIST Score

Authors’ Conclusions: In this prospective validation of the TWIST score among pediatric emergency providers, the high-risk score demonstrated strong test characteristics for testicular torsion. The TWIST score could be used as part of a standardized approach for evaluation of the pediatric acute scrotum to provide more efficient and effective care.”

checklistQuality Checklist for Clinical Decision Tools:

  1. The study population included or focused on those in the emergency department. YES.
  2. The patients were representative of those with the problem. YES
  3. All important predictor variables and outcomes were explicitly specified. YES
  4. This is a prospective, multicenter study including a broad spectrum of patients and clinicians (level II). NO
  5. Clinicians interpret individual predictor variables and score the clinical decision rule reliably and accurately. NO
  6. This is an impact analysis of a previously validated CDR (level I). NO
  7. For Level I studies, impact on clinician behavior and patient-centric outcomes is reported. NA
  8. The follow-up was sufficiently long and complete Unsure
  9.  The effect was large enough and precise enough to be clinically significant. Unsure

Key Results: 778 patients presented to the ED with acute testicular/scrotal pain or swelling. 258 patients were enrolled in the study with a mean age of 10 years. The diagnosis of testicular torsion was made in and 19 (7.4%) patients. Ultrasound identified 16 out of the 19 patients.

The higher the TWIST score the higher the risk of testicular torsion

  • Primary Outcome:
    • Patients with testicular torsion had a statistically significantly higher mean TWIST score than those without torsion, 4.2 compared to 1.6, respectively.
    • A TWIST score of 7 had a specificity and PPV of 100% for testicular torsion, and a sensitivity of 21%.
    • There were a few patients with low TWIST scores that also had testicular torsion.

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1) Convenience Sample: Patients were only enrolled when a research assistant was available. 233 patients with testicular pain were missed, and of those 36 (15%) had a diagnosis of testicular torsion, which was over twice the rate of torsion as the enrolled patients (7%).

2) Double-Gold Standard: Patients with a positive index test are more likely to receive an immediate, invasive gold standard, whereas patients with a negative index test are more likely to receive clinical follow-up for development of disease. (Kohn et al 2013). Every patient in this study had an ultrasound but only those with a positive ultrasound went on to surgery. Those with a negative ultrasound were followed clinically. Ultrasound is not a perfect test and there could have been false negatives that were not identified in their follow-up strategy.

3) Prevalence: The prevalence in this study was lower than they expected (7%). This results in wider confidence intervals around the point estimates for the test characteristics of the cut points for the TWIST score.

Value of kappa4) Inter-Rater Reliability:  The overall TWIST score had only fair agreement between providers with a kappa value of 0.39 (95% CI .22-.46). History of nausea and scrotal swelling had the highest kappa values at 0.75 and 0.74, respectively. Absent cremasteric reflex had a kappa of 0.52 and a hard testicular mass had the lowest kappa at 0.25.

5) External Validity: This study was conducted in a pediatric ED at a tertiary care pediatric hospital. We are unsure how the TWIST score would perform in a community ED that sees children.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: Given that agreement on the TWIST score was fair, the large proportion of missed patients, and that a high-risk score was considered >5 in the original study as compared to 7 in this study, it may not be wise to eliminate ultrasound examination in these patients just yet.

SGEM Bottom Line: The TWIST score needs further multi-center validation among emergency department patients presenting with acute testicular pain and swelling before implementation into a protocol.

Case Resolution: Our patient has a TWIST score of 4, receiving 2 points for testicular swelling, 1 point for absent cremasteric reflex, and 1 point for vomiting. Despite your high level of suspicion, you are going to send your patient for an ultrasound examination to confirm the diagnosis of torsion before committing him to surgical intervention.

Clinically Application: Unless your patient is hitting a TWIST score of 7, you should strongly consider obtaining a diagnostic ultrasound to confirm the diagnosis of testicular torsion if that ultrasound can be performed in a reasonable time frame.

Dr. Melissa Langhan

Dr. Melissa Langhan

What Do I Tell My Patient? Brian, your pain could be due to a twisting of your testicles (balls) called torsion. This can cut off the blood supply and permanently damage your testicle. You will need urgent surgery if the blood supply has been blocked. There is a scoring system we use with 0 being the lowest (less worried) and 7 the highest (most worried). Your score is in the middle at 4 which means it could be something else. To find out the right diagnosis we have ordered an urgent ultrasound. While we get that arranged would you like some pain medication?

Keener Kontest: Last weeks’ winner was David McAdams. He knew Dr. Thomas Latta was the first physician to use intravenous fluids during the London cholera outbreak of 1832. 

Listen to the SGEM podcast on iTunes to hear this weeks’ question. If you know the answer send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.

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