Thermal asymmetry of the human scrotum

Scrotal temperatures in men have been reported to be either similar on both sides or higher on the left than the right scrotum. We aimed to clarify this discrepancy from new data.

Retrospective analyses of scrotal temperatures in men aged 20-52 years measured every 2 min with probes connected to a data collector in three experiments. In Experiment I, eight men have been submitted to four successive body positions for 15 min each, first naked then clothed. Experiment II involved 11 postal employees working in a standing position for 90 min continuously. Experiment III involved 11 bus drivers and a 90 min period of continuous driving. Outcome parameters were left and right scrotal temperatures.

In Experiment I, mean values and kinetics of scrotal temperature differed significantly in the naked and clothed state. In all three experiments, left scrotal temperature in the clothed state was higher than right scrotal temperature in terms of mean values and temperature kinetics.

Lack of thermal symmetry was seen in the right and left scrotum, whether naked or clothed, and this applied regardless of position or activity when clothed. This thermal difference between right and left scrotum could contribute to the asymmetry in the male external genital organs.