title: Pregnancy- and delivery-induced biomechanical changes in rat vagina persist postpartum.
abstract: OBJECTIVE
  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.
authors.affiliation: Division of Urogynecology and Reconstructive Pelvic Surgery, University of Pittsburgh, Pittsburgh, PA, USA. manusha30@yahoo.com
authors.forename: Marianna
authors.initials: M
authors.lastname: Alperin
authors.forename: Andrew
authors.initials: A
authors.lastname: Feola
authors.forename: Robert
authors.initials: R
authors.lastname: Duerr
authors.forename: Pamela
authors.initials: P
authors.lastname: Moalli
authors.forename: Steven
authors.initials: S
authors.lastname: Abramowitch
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001696:Biomechanical Phenomena; D005260:Female; D049590:Postpartum Period / Q000502:physiology*; D011247:Pregnancy; D011270:Pregnancy, Animal / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D014621:Vagina / Q000502:physiology*