International Urogynecology Journal

, Volume 21, Issue 10, pp 1231–1236 | Cite as

Extraordinary muscular structure leads to urethral injury after vaginal delivery in animal study

  • Hung-Yen Chin
  • Eileen Changchien
  • Chi-Hsin Chiang
  • Hsiu-Ping Yang
Original Article


Introduction and hypothesis

The aim of this study is to explore causality of birth trauma after vaginal delivery and anatomical findings.


A total of 28 virgin mice were studied. Treatment groups received vaginal distention. Specimens were collected and subjected to the following fluorescence stains: progenitor cell (c-kit), smooth muscle (SMA), fibroblast (vimentin), and skeleton muscle (Masson’s trichrome). Confocal microscopy was used to screen all of the urogenital tissue to localize the stained cells.


Fibroblasts were spread all over perivaginal and urethral surroundings. Progenitor cells appeared at urethral–vagina intersection and urethral circle. They were noticeable only within smooth muscle layer. Two extraordinary skeleton muscle bands appeared on the urethra bilaterally.


Our study demonstrates existence of muscle bands at the bilateral urethra. They can limit the mobility of urethra during vaginal delivery and thereby cause urethra injury. Progenitor cells are located only in the smooth muscle of the urethral circle.


Birth trauma Fibrosis Stem cells Urethral injury Urinary incontinence Urogenital structure 



The study was granted approval from Chang Gung Memorial Hospital with the registration number of CMRPG260481.

Conflicts of interest



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Copyright information

© The International Urogynecological Association 2010

Authors and Affiliations

  • Hung-Yen Chin
    • 1
    • 3
  • Eileen Changchien
    • 2
  • Chi-Hsin Chiang
    • 3
  • Hsiu-Ping Yang
    • 3
  1. 1.Medical SchoolChang Gung UniversityTao-YuanRepublic of China
  2. 2.R & D, Standard Chemical and Pharmaceutical. Co., LtdTainanRepublic of China
  3. 3.Department of Obstetrics and GynecologyChang Gung Memorial HospitalKeelungRepublic of China

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