Testicular volume: correlation of ultrasonography, orchidometer and caliper measurements in children

Testicular size assessment is an important and initial technique for the evaluation of gonadal function. Our study aims to determine the correlation between paediatric testicular volumes measured with the orchidometer, high-resolution ultrasonography (US) and intra-operative measurements using calipers. This is a prospective observational study of 127 boys presenting to our institution with non-emergent scrotal conditions between January 2007 and October 2008. Volume estimates of both testes were measured using the Prader orchidometer. The patient was then sent to a radiologist who measured the testicular volumes using US, being blinded to the orchidometer estimates. At surgery, the testicular dimensions on the side of the pathology were obtained with a vernier caliper. The testicular volumes by US and caliper were calculated using the formula 0.71 × Length × Width × Height. The relationship between the measured volumes was determined using Pearson’s correlation statistic and Student’s t test. The level of significance for all analysis was set at p < 0.05. Their ages ranged from 18 days to 13 years (median 3 years). There was significant correlation between testicular volumes (for both sides, i.e. right and left) measured with the orchidometer and US (r = 0.544; 0.537, p < 0.001), significant correlation between testicular volumes measured with the orchidometer and caliper (r = 0.537; 0.638, p < 0.001) and also significant correlation between volumes measured by US and caliper (r = 0.382; 0.829, p < 0.01). Prader orchidometer testicular volume estimates correlate significantly with US estimates in children. In resource-constrained settings, it could be used for an accurate and quick testicular volume assessment.