Long-term protective effects of hypothermia on reperfusion injury post-testicular torsion

As many as two-thirds of salvaged testes post-torsion will atrophy within 2 years. Subsequent testicular damage is due at least in part to an ischaemia/reperfusion injury. Thus we analysed the long-term protective effects of subjecting the ischaemic testis to hypothermia in an attempt to prevent or attenuate subsequent testicular damage.

Forty male Sprague-Dawley rats (mean age 97 days; mean weight 408 g) were randomized to one of two groups. The left testis was removed as a control and the right testis was subjected to torsion through 720 degrees in a clockwise direction and maintained in this position for 3 h. Half of the models were subjected to hypothermia by submerging the testis in a cooling bath, which was kept at a constant temperature of 2-4 degrees C for the final hour prior to detorsion. Testes were retrieved at 1 and 12 weeks and examined by a single blinded pathologist using the following histological criteria: mean seminiferous tubular diameter, mean tubular wall thickness (MTWT) and Johnsen's score.

Histological examination revealed significant injury after 1 week of reperfusion in both groups. However, after 12 weeks of reperfusion there was a marked benefit seen in the testes subjected to hypothermia. MTWT (p=0.007) and Johnsen's score (p=0.05) were significantly better in the cooled testes after 12 weeks of reperfusion.

Hypothermia reduces the degree of long-term testicular damage post-torsion and, if applied in clinical practice, may improve long-term salvage rates.