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Three Part Question

In [patients with an acute scrotum] is [TWIST Score] a [reliable diagnostic tool for testicular torsion]?

Clinical Scenario

An 18 year old male presents to the emergency department with unilateral testicular pain and swelling. You are unsure whether you can safely discharge or whether he requires further urological work up for testicular torsion.

Search Strategy

OVID Interface MedLine 1946 - May week 5 2018
OVID EMBASE search 1980-week 24 2018


MEDLINE search: (Testicular Torsion.mp OR exp spermatic cord torsion/) AND (TWIST.mp OR scoring system$.mp OR score.mp) - LIMIT to Humans and English Language yielded 25 results, 2 of which were relevant

EMBASE search: (Testicular torsion.mp OR exp testis torsion/) AND (TWIST.mp OR scoring system$.mp OR score.mp) - LIMIT to Human and English Language yielded 69 results of which 4 were relevant 2 duplicated in Medline

Search Outcome

4 papers were included. (See Table).

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Barbosa JA, Tiseo BC, et al 2014 USA	338 patients age 3mth-18yr presenting with acute scrotum	Prospective with retrospective validation	Correct diagnosis of testicular torsion	For a cut off of 2 (low risk) NPV was 100% (95% CI 98 –100) and sensitivity was 100% (95% CI 91–100). PPV was 100% (95% CI 88 –100) for a cutoff of 5 (high risk) and specificity was 100% (95% CI 98 –100).	Requires testing and validation by non-experts
Sheth KR, Keays M, et al. 2016 USA	128 patients aged 1mth-21yr assessed in ED	Prospective validation study	Diagnosis of Testicular Torsion	The Authors found 100% sensitivity in the low risk group.	Used different cut off values to initial study (0 = low risk, 1-5 = intermediate risk, 6-7 = high risk).
Frohlich LC, Paydar-Darian N, et al. 2017 USA	258 male patients aged 3mth-18yr in PED	Prospective cohort	Correct diagnosis of testicular torsion	The sensitivity for the low risk group was 98.1%. The TWIST score of seven had a sensitivity of 21% (95% CI = 6%–45%), a specificity of 100% (95% CI = 98%– 100%), and a PPV of 100% (95% CI = 40%–100%. None of the 111 patients who had TWIST scores of 0-1 had torsion.	Convenience sample and only 52% of eligible patients enrolled.
Manohar AS, Gupta A, et al. 2018 India	118 Males aged 6-28yrs	Retrospective cohort study	Correct diagnosis of testicular torsion	NPV and sensitivity of TWIST score for low risk patients were 96.6% and 95.5%, respectively, while PPV and specificity for high risk patients were 92.8% and 97.2%, respectively.	Selection bias - tertiary centre catering for majority of referral cases Retrospective study

Comment(s)

The TWIST (Testicular Workup for Ischemia and Suspected Torsion) Score was developed by Barbosa et al to stratify patients with suspected torsion into risk groups for diagnosis. It includes five clinical variables: Testicular swelling (2 points) Hard testicle (2 points) Absent cremasteric reflex (1 point) Nausea/vomiting (1 point) High-riding testis (1 point) The total score can range 0–7. Patients are divided into low-, intermediate-, or high-risk groups on the basis of total score (0–2, 3–4, 5–7, respectively). Barbosa et al found 100% negative predictive value (NPV) for low-risk group and 100% positive predictive value (PPV) for high-risk group. They have suggested that Doppler is not required in low- and high-risk groups, and patients in high-risk group can be directly taken for surgical exploration. All other studies found the sensitivity for the low risk group to be between 95-100%. The specificity for the high risk group was 97-100% among studies. Different cut-off values were used between studies, however, which reduces the clinical utility of these findings. It should also be noted that the above studies mainly looked at paediatric populations and a few young adults. The findings may not be generalisable to an adult population.

Editor Comment

JB

Clinical Bottom Line

In the ED setting, the main utility of the TWIST score is deciding whether patients fall into the low risk category and can thus be safely discharged. A low risk TWIST score has a high sensitivity and can be used in line with clinical judgement as a diagnostic tool to rule out testicular torsion.

References

1. Barbosa JA, Tiseo BC, et al. Development and initial validation of a scoring system to diagnose testicular torsion in children The Journal of Urology 2014 Aug;192(2):619.
2. Sheth KR, Keays M, et al. Diagnosing Testicular Torsion before Urological Consultation and Imaging: Validation of the TWIST Score. The Journal of Urology 2016 Jun;195(6):1870-6
3. Frohlich LC, Paydar-Darian N, et al. Prospective Validation of Clinical Score for Males Presenting With an Acute Scrotum Academic Emergency Medicine Dec 2017; 24(12) 1474–1482
4. Manohar AS, Gupta A, et al. Evaluation of Testicular Workup for Ischemia and Suspected Torsion score in patients presenting with acute scrotum Urology Annals 2018 Jan-Mar; 10(1): 20–23.