The interrelationship of childbirth-related pelvic floor injury in primiparas after vaginal delivery

Abstract

Abstract Objective This study aimed to explore the underlying relationship between the pubic bone injury and levator ani muscle injury. Methods 150 primiparas after vaginal delivery were prospectively enrolled and divided into the pubic bone injury group and the non-pubic bone injury group according to imaging appearance on postpartum magnetic resonance imaging. The levator ani muscle morphology and function were evaluated, including injury score, H line, M line, levator plate angle, iliococcygeal angle, and levator hiatus area. The levator ani muscle morphology and function were compared between the two groups using univariate analysis. The association between the severity of the pubic bone injury and the levator ani muscle injury was calculated using the Spearman or Kendall's tau-b correlation coefficient. Results Compared to the non-pubic bone injury group, the pubic bone injury group more frequently complained of pelvic pain and stress incontinence (28% vs. 9.3%, P = 0.003; 29.3% vs. 13.3%, P = 0.017, respectively). The levator ani muscle morphological injury score, the H line at straining, the M line, and the levator hiatus area at rest and straining were different between the two groups (all P < 0.05). There was a positive correlation between the severity of the pubic bone injury and levator ani muscle injury score (r = 0.332), M line (r = 0.139, 0.150), and levator hiatus area (r = 0.181, 0.164) at rest and straining, respectively (all P < 0.05). Conclusions The pubic bone injury was a reliable reminder of morphological injury and decreased function in levator ani muscle.