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Three Part Question

In [patients presenting with acute unilateral testicular pain] is [a positive Prehn’s sign] an [accurate sign for diagnosis of testicular torsion]?

Search Strategy

Databases: Medline, Embase (2013-2018), Cochrane

Search Terms: (“Testicular Pain” OR “Scrotal Pain” OR “Acute Scrotum”).mp AND “Prehn’s”.mp AND ("Testicular Torsion" OR "Spermatic Cord Torsion" OR "twisted testis").mp

Search Outcome

No papers were found on Medline or Cochrane. Four papers were found on Embase.

After duplications were removed, 4 papers remained; of these, one was relevant to the three-part question.

Relevant Paper(s)

Author, date and country	Patient group	Study type (level of evidence)	Outcomes	Key results	Study Weaknesses
Roth et al 2018 Switzerland	440 patients with acute scrotum in Switzerland, between 01/2003–01/2013.		9.5% had TT. 33% of TT patients had a positive Prehn’s sign (OR 5.941).		No Prehn’s sign data for non-TT acute scrotum causes.

Comment(s)

The retrospective analysis by Roth et al. reviewed patients aged 16-to-76 years old and thus doesn’t include the mean incidence age (13.0 years). Patients were of the same demographic (residents of Bern, Switzerland), so conclusions may not represent other nations. The paper doesn’t mention Prehn’s sign Odds Ratio (OR) for other urological conditions, such as epididymitis. This, therefore, doesn’t allow physicians to use Prehn’s findings to distinguish between TT and other causes of acute scrotum. The study also fails to identify an individual test which can diagnose TT, and instead suggests a cumulative approach, including a positive Prehn’s sign.

Clinical Bottom Line

A positive Prehn’s sign is in-keeping with TT, so must be considered to aid diagnosis. However, a negative sign cannot be used to rule out TT.

References

1. Roth et al An accurate diagnostic pathway helps to correctly distinguish between the possible causes of acute scrotum