The effect of mode of delivery on pelvic floor functional anatomy

Abstract

The objective of this study is to investigate and compare the effects of different modes of delivery on urethral sphincter volume, bladder neck mobility, and changes to levator hiatus distensibility using ultrasound imaging. This study is a prospective observational cohort study. The setting of this study is at a London teaching hospital. The population is composed of 156 women recruited in their first ongoing pregnancy. Primigravid women were recruited between 32 weeks and term. Antenatal ultrasound measurements of levator hiatus and bladder neck mobility were assessed at rest, maximum strain, and maximum valsalva using transvaginal ultrasound imaging. Urethral sphincter volume was calculated using a three-dimensional transvaginal probe. The investigations were repeated at 6 weeks and at 6 months postpartum. Total urethral sphincter volume, rhabdosphincter volume, bladder neck position at rest, and rotational mobility from maximum contraction to maximum valsalva were measured in this study. Levator hiatus area at rest and levator hiatus on valsalva and squeeze were also measured. The 156 women underwent antenatal ultrasound pelvic floor assessment. One hundred ten (71%) completed the 6-month follow-up. There were no differences in the urethral sphincter volume between the different modes of delivery. Overall, the urethral sphincter was smaller after delivery compared to the third trimester. Vaginal delivery was associated with a significantly larger levator hiatus area on valsalva antenatally and at rest, squeeze, and valsalva postnatally compared to caesarean section. Antenatal and postpartum bladder neck mobility was also significantly greater in the women who delivered vaginally. Urethral sphincter changes postpartum are independent of mode of delivery. Vaginal delivery is strongly associated with a larger, more distensible levator hiatus and a greater degree of bladder neck mobility both antenatally and postpartum.

Hysterectomy and Lower Urinary Tract Symptoms: A Nonrandomized Comparison of Vaginal and Abdominal Hysterectomy

“…This downward traction might also cause more supportive system damage and hypermobility of the urethra. The same effect has been described after vaginal delivery compared to caesarean section [21,22] .…”

Prevalence of urinary incontinence in reproductive women and its impact on quality of life

“…Several studies evaluated the bladder-neck mobility using ultrasound after the first delivery. 23 They showed that bladder-neck mobility was increased after vaginal delivery and unchanged after cesarean. Fritel et al, in their study showed that cesarean was significantly associated with a lower risk of SUI compared to normal delivery.…”

Effect of pelvic floor muscle training on labour and newborn outcomes: a randomized controlled trial

“…Some studies indicate that women with stress urinary incontinence and bladder neck mobility have lower pelvic floor muscle strength 14,27 . Others indicate that vaginal delivery is correlated with larger levator hiatus diameter and greater bladder neck mobility 28 . It is plausible to suggest that these women may have less pelvic floor muscle strength.…”