Continued use of scrotal ultrasounds for the workup of undescended testes: Confirmation bias and inaccuracies.

AIM: Scrotal ultrasounds are utilised in some primary care settings for suspected cryptorchidism, despite inaccuracies. We aim to identify the correlation between ultrasound and primary care provider (PCP) findings of undescended testicles (UDTs) as a potential source of confirmation bias.

METHODS

Males referred for suspected UDT by PCPs who underwent scrotal ultrasound and paediatric urologist examination from 2014 to 2019 were included. Correlation between PCP and ultrasound findings and diagnostic accuracy were evaluated. Logistic regression was utilised to determine associations between patient factors and UDT misdiagnosis.

RESULTS

Out of 145 testes, ultrasound corroborated PCPs' UDT diagnoses 87.6% of the time, 49.6% of which were confirmed as UDT by paediatric urologists. Ultrasound had a false positivity rate of 81.0% and specificity of 19.0%. Ultrasound versus paediatric urologist findings regarding testicle location were significantly different (P < 0.0001). Patients aged ≥8 years old had 5.2 times greater odds of being misdiagnosed with UDT than patients <8 years old (95% confidence interval: 1.6-16.7; P < 0.002) by PCP and ultrasound.

CONCLUSION

Scrotal ultrasound highly corroborated PCPs' UDT diagnoses. Older patients were more likely to be misdiagnosed with UDT by PCP and ultrasound. As ultrasounds rarely refute PCP examinations for suspected UDTs and are highly inaccurate, confirmation bias may explain the use of ultrasound in the workup of UDT.