The effect of vaginal delivery on the urethral sphincter

Abstract

To investigate the actiological role of vaginal delivery in genuine stress incontinence we compared two groups of women who underwent full urodynamic assessment in our department. The women in the first group had competent urethral sphincter mechanisms and those in the second group had genuine stress incontinence. There were no differences between the two groups in respect of parity, number of vaginal deliveries or birthweight of the heaviest baby. The group with competent urethral sphincter mechanisms did show some cvidencc to implicate an increased number of vaginal dcliverics in poor function of the distal part of the urcthral sphincter rncchanism.Genuine stress incontinence i s the tnost common cause of feniale urinary incontinence and has traditionally been associated with pregnancy. vaginal delivery, previous incontinence surgery, congenital weakness and the menopause. Thomas (1984) found that the prevalence of strcss incontincnce increased with increasing parity. Rcccnt corroborative evidence that vaginal delivery may be an important actiulogical factor has been provided by investigations of urcthral and anal sphincter electrophysiology. and urethral prcssure mcasurernents.Paticnts with genuine stress incontinence have abnormal conduction in the perineal branch of the pudcndal nerve which innervates the peri-JULIA MON'I'GOMERY RPsrarrh R q i s / m r J OH N S'I 'U DD C'o/zsulrcm Correspondence: A Tapp, Kegislrar, Department 01 Obstetrics arid Gyn;iccolog>. Grcenwicli District Hospital. Vanbrugh Hill, 1,ondon SElO YHE fernale continence. Bv !Wed J 292, 166-167. 72, S 15-17.

Female urinary incontinence: a cross-sectional study from a Thai rural area

“…Regarding the mode of delivery, it has been known that vaginal delivery may cause damage to important muscle tissue or nerves of the pelvic floor through mechanical strain during labour. In addition, previous studies have noted that substantial bladder neck hypermobility, together with a reduction in functional urethral length, urethral closure pressure and maximum urethral pressure, was observed after vaginal delivery [27,28]. Thus, women who delivered by vaginal route more frequently suffered from symptoms of stress urinary incontinence compared with those who had caesarean delivery.…”

Impact of pregnancy and childbirth on female rats’ urethral nerve fibers

“…Multiparity seems to have a cumulative effect in the neuromuscular function of the pelvic floor and repeated trauma would promote further urethral dysfunction at each vaginal delivery [12,22]. The trauma produced by natural childbirth can affect the continence mechanism provoking lesions in the outlying innervation of the pelvic periurethral musculature.…”

“…Obesity, chronic cough, race, smoking, and constipation can also contribute to UI [7][8][9][10][11][12][13][14][15]. Many authors have described the role of childbirth as a predisposing factor for urinary incontinence [16][17][18][19][20][21].…”

The risk of lower urinary tract symptoms five years after the first delivery*

“…Delivering twins did not increase the risk of urinary incontinence in primiparae [Viktrup et al, 1992], whereas genuine stress incontinence in middle-age women did not relate to fetal weight during previous delivery [Tapp et al, 1988].…”

“…In 237 middle-aged women with or without stress incontinence, the impact of fetal weight has been evaluated urodynamically [Tapp et al, 1988].…”