Parturition and Urinary Incontinence in Primiparas
Parturition and Urinary Incontinence in Primiparas
Abstract & Commentary
Synopsis: Vaginal delivery is associated with a higher risk of urinary incontinence than cesarean delivery.
Source: Farrell S, et al. Obst Gynecol. 2001;97: 350-356.
Several articles have shown that pregnancy causes injury to pelvic nerves, and that vaginal delivery is more likely to increase the severity of the nerve injury than cesarean delivery. Other factors that have irregularly been shown to be important include maternal weight, parity, instrument delivery, length of second stage, and episiotomy.
The purpose of this study was to compare the frequency of postpartum urinary incontinence among healthy primiparous women with various types of vaginal deliveries. Women were enrolled in the study during their prenatal visits. In order to participate they could have no history of urinary tract abnormalities or pelvic surgery, nor could they have a significant medical illness. The women completed an incontinence questionnaire at the time of enrollment, at 6 weeks postpartum, and at 6 months postpartum. The questionnaire was pretested on a group of women with known genuine stress incontinence and was found to be 100% sensitive. Appropriate definitions of the severity of incontinence and the length of the various stages of labor were used.
A power analysis was performed which indicated that approximately 450 women would need to be enrolled in the study. Appropriate statistical analyses were performed on the data and logistic regression analysis was performed to test for significance of univariate variables. Six hundred-ninety women were initially enrolled, but because of spontaneous abortion, mobility of the population, and loss to outlying hospitals, 595 women completed the 6-week questionnaire. Four hundred eighty-four women completed the 6-month questionnaire. Eighty of the 593 eligible women who completed the prenatal questionnaire were found to have some incontinence prior to delivery.
Among those women who were continent before delivery, 10% of those undergoing cesarean delivery, 22% experiencing spontaneous vaginal delivery, and 33% of forceps deliveries had incontinence at the time of the 6-week questionnaire. There was no significant difference in the rate of incontinence between those women who had cesarean delivery before labor compared to those who had a cesarean delivery during the second stage of labor. After appropriate statistical analysis, no factor relating to labor—infant size, maternal weight gain, or maternal age—was a significant predictor of urinary incontinence. Thus, only the performance of a cesarean delivery was significant in reducing the rate of incontinence.
Among the 80 patients who reported urinary incontinence at study entry prior to delivery, 60% continued to have incontinence when questioned postpartum.
In the discussion, Farrell and colleagues note that there is "a growing body of evidence finding that vaginal birth has a detrimental effect on the pelvic floor." However, they also note that, with the exception of cesarean delivery, no manipulation of normal labor has yet been shown to reduce the risk of incontinence. They also remind readers that incontinence does follow cesarean delivery, and that injury to the pelvic nerves has been documented with this method of delivery.
Comment by Kenneth L. Noller, MD
It has been interesting to watch and listen to the cesarean delivery battle during the past decade. The first important debate began when cesarean delivery rates started to increase. While much of the increase seemed (seems) to be appropriate, some hospitals began reporting cesarean deliveries in excess of 35-40%. Such rates seemed (seem) excessive.
Then, out of nowhere, the Healthy Women 2000 guidelines suggested that the "ideal" cesarean delivery rate was 15%. Insurance companies immediately jumped on this benchmark and expected hospitals participating in their plans to meet it. In some cases, hospitals were denied payment or received reduced payment for excessive cesarean delivery rates.
During this attack, physicians responded by increasing the frequency of vaginal delivery after cesarean section (VBAC). Recently, it has become clear that VBAC is not a low-risk procedure, and that patients must be carefully selected.
Many obstetricians thought the war ended there. However, there has now appeared another spectre on the horizon: urinary incontinence. Slowly over the past several years, the data have been accumulating which indict vaginal delivery as the cause of most urinary incontinence. And, to make matters worse, cesarean delivery seems to prevent the condition in most cases.
Of course, you know where I’m heading. There has been more and more talk about "cesarean delivery on demand." As we have all heard, the upper class in some countries routinely have cesarean delivery rather than vaginal. Are we headed the same way? While I certainly hope not, my lack of confidence in the US legal system does discourage me. I expect that there soon will be a "lack of informed consent" malpractice suit because an obstetrician did not tell the patient she would be more likely to have urinary incontinence if she delivered vaginally than if she had elected cesarean delivery. I suspect it is only a matter of time. Perhaps the 30% cesarean delivery rates we were all upset about a decade ago will seem low in the future.
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