With a new clip technique surgically inducing varicocele in Sprague-Dawley rats

Background We introduced and recreated a more consistent and effective experimental varicocele rat model by a new clip technique. Methods A total of 40 rats were numbered and randomly assigned to 5 groups of 8 each, including sham surgery (Group I), conventional (Group II) and clip groups with 0.7, 0.8, 0.9 mm gap widths, respectively (Group III, IV, V). All of the rats in each group were sacrificed at 8 weeks after initial surgery, and the rats forming out with less than 1 mm diameter of left spermatic vein or no presence of the pampiniform plexus dilation were excluded from the experimental groups. The left spermatic vein (LSV) diameter, testicular weight, left kidney weight to body weight coefficients, kidney and testicular histology were determined. Results The baseline mean diameter of the LSV in Group I, II and III was 0.22 ± 0.02, 0.23 ± 0.02 and 0.22 ± 0.03 mm, respectively ( P = 0.7504). At 8 weeks after initial surgery, varicocele was successfully created in 6/8 (75%), 7/8 (87.5%), 3/8 (37.5%), 3/8 (37.5%) in GroupII-V, no varicocele was observed in Group I. In Group I, II and III, no pathological changes were observed and the left kidney weight to body weight coefficients showed no significant differences. The diameter of LSV was remarkably increased both in Group II and III compared to Group I (1.72 ± 0.13, 1.57 ± 0.19 and 0.25 ± 0.02, respectively), and Group II and III had a smaller testicular weight than the rats in Group I (1.67 ± 0.05, 1.62 ± 0.06, and 1.92 ± 0.12, respectively). Conclusions With a new clip technique, surgically inducing varicocele rat model becomes convenient and safe. This appears to improve the effectiveness of the model and this innovation may allow us to further understand the pathophysiology of varicocele.