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Updated: Jun 13, 2026
Biaxial Basal Tone and Passive Testing of the Murine Reproductive System Using a Pressure Myograph
Published on: August 13, 2019
Pregnancy- and delivery-induced biomechanical changes in rat vagina persist postpartum
Marianna Alperin1, Andrew Feola, Robert Duerr
1Division of Urogynecology and Reconstructive Pelvic Surgery, University of Pittsburgh, Pittsburgh, PA, USA. manusha30@yahoo.com
Introduction And Hypothesis:
We sought to define changes in vaginal distensibility (VD) induced by pregnancy and vaginal delivery using a novel in vivo biomechanical testing protocol.
Methods:
Under sedation, a balloon was inserted into the vagina of 27 virgin, pregnant and 4-week postpartum Long-Evans rats and incrementally distended. Pressure-volume curves were generated with slopes characterizing VD (higher slope = less distensible). One-way ANOVA with a Bonferroni post-hoc test were used for statistical analyses.
Results:
Mean pressures at an infusion volume of 1 cc were lower in pregnant and postpartum rats than in virgins (P < 0.001). VD was increased in pregnant vs. virgin rats (P < 0.001) and did not recover to virgin levels post partum (P < 0.001).
Conclusions:
We have developed a test that measures VD in vivo under clinically relevant loading conditions. The increased VD in the late postpartum period defines a persistent change in biomechanical behavior of the vagina related to pregnancy and vaginal delivery.
