The impact of cesarean delivery on pelvic floor dysfunction in lysyl oxidase like-1 knockout mice
Objective: Lysyl oxidase like-1 (LOXL1) knockout mice have abnormal elastic fiber homeostasis and frequently develop pelvic floor dysfunction after pregnancy and delivery. The objective of this study was to test the hypothesis that tissue changes associated with vaginal delivery lead to pelvic floor dysfunction as a result of abnormal elastic fiber homeostasis. Methods: Female LOXL1 knockout mice delivered either spontaneously or by cesarean delivery. Mice were assessed weekly for pelvic organ prolapse (POP). At 12 weeks postpartum, lower urinary tract function was assessed by cystometry and leakpoint pressure testing. Urethrovaginal cross-sections were analyzed using a histologic grading scale to assess elastin fiber disorganization. Results: A total of 39 mice delivered by spontaneous vaginal delivery and 36 by cesarean delivery. Twelve weeks after spontaneous vaginal delivery or cesarean delivery, 23 (59%) and 11 (31%) mice had developed POP, respectively. The mean time to develop POP was 7.2 weeks after spontaneous vaginal delivery and 10.5 weeks after cesarean delivery (log rank, P = 0.0008). The Cox proportional hazard ratio was 0.55 (95% confidence interval, 0.38-0.79). Mice with POP had increased frequency of bladder contractions not associated with voiding during cystometry (P = 0.02). POP, but not mode of delivery, was associated with increased elastic fiber disorganization. Conclusions: Cesarean delivery delays the development of POP in LOXL1 knockout mice. POP is associated with increased bladder contraction frequency and increased elastic fiber disorganization in the urethra and vagina. The mechanisms underlying these findings warrant further investigation. Copyright © 2010 by Lippincott Williams & Wilkins.
