Vaginal Septum Resection Technique for Optimizing Fertility in Mice

A vaginal septum is a congenital anomaly in which a fibrous tissue band divides the vaginal canal longitudinally. Humans diagnosed with vaginal septum may suffer negative effects on fertility and childbirth. Similarly, mice with a vaginal septum may exhibit poor fertility, prolonged breeding times, and labor dystocia. High rates of vaginal septum in some mouse colonies, with reports as high as 38%, can delay breeding programs and increase animal housing costs. To address this problem, we developed a surgical approach to remove the septum and restore reproductive function in affected mice. Female mice from our colony were screened at 6-8 weeks of age and assigned to three groups: septum resection, septum without resection, and nonseptate controls. Septal tissue was excised under general anesthesia using microscissors and a dissection microscope. Compared with septate mice that did not undergo surgery, mice that underwent resection had higher copulatory plug rates (82% vs. 46%, p < 0.05), higher pregnancy rates after 30 days of breeding (95% vs. 36%, p < 0.0001), higher pregnancy rates after 75 days of breeding (100% vs. 72%, p < 0.01), and a shorter time to pregnancy (p < 0.01). Mice that underwent septum resection showed normalization of reproductive outcomes, including copulatory plug rates and pregnancy rates, to levels comparable to the nonseptate control mice. This suggests that resection of a longitudinal vaginal septum can restore reproductive performance in affected mice while reducing breeding delays, resource use, and animal waste in laboratory colonies.