Abstracts

INTRODUCTION

Elective cesarean section without labor is a common procedure in Brazil, accounting for more than 40% of births. In the past, this procedure was thought to protect against urinary incontinence.¹1. Rudge MV, Maestá I, Moura PM, et al. The safe motherhood referral system to reduce cesarean sections and perinatal mortality - a cross-sectional study [1995-2006]. Reprod Health. 2011;8:34. However, there are doubts as to whether an elective cesarean section confers an independent protective effect against urinary incontinence. Incontinence rates have not been correlated with delivery method, but elective cesarean sections without attempting labor have been associated with a significantly lower prevalence of postpartum urinary incontinence.²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8.

It is questionable whether cesarean section delivery can prevent pelvic floor injury,³3. Chaliha C. Postpartum bladder dysfunction. Reviews in Gynaecological and Perinatal Practice. 2006;6(3-4):133-9.−⁵5. McKinnie V, Swift SE, Wang W, et al. The effect of pregnancy and mode of delivery on the prevalence of urinary and fecal incontinence. Am J Obstet Gynecol. 2005;193(2):512-7; discussion 517-8. but recent data have suggested that this protective effect is less pronounced and that gestational urinary incontinence appears to be the most important predictive factor for developing postnatal urinary incontinence.⁶6. Phillips C, Monga A. Childbirth and pelvic floor: “the gynaecological consequences”. Reviews in Gynaecological Practice. 2005;5:15-22. Available from: http://assoalhopel.dominiotemporario.com/doc/Childbirth_and_the_pelvic_floor.pdf. Accessed in 2012 (Jun 1).
http://assoalhopel.dominiotemporario.com... −⁸8. Fritel X, Fauconnier A, Levet C, Bénifla JL. Stress urinary incontinence 4 years after the first delivery: a retrospective cohort survey. Acta Obstet Gynecol Scand. 2004;83(10):941-5. The risk of urinary incontinence has been found to be higher among women who had only experienced cesarean delivery than among nulliparous women, and even higher among those who had only delivered vaginally.⁹9. Rortveit G, Daltveit AK, Hannestad YS, Hunskaar S; Norwegian EPINCONT Study. Urinary incontinence after vaginal delivery or cesarean section. N Engl J Med. 2003;348(10):900-7.

In women without urinary incontinence, the pelvic floor muscles contract simultaneously with or immediately before increases in abdominal pressure as an unconscious involuntary automatic co-contraction.¹⁰10. Sapsford RR, Hodges PW. Contraction of the pelvic floor muscles during abdominal maneuvers. Arch Phys Med Rehabil. 2001;82(8):1081-8. A variety of methods have been used in clinical practice and research to evaluate pelvic floor muscle function and strength, but no single measurement tool provides a full picture of pelvic floor muscle strength or function with sufficiently demonstrated responsiveness, reliability and validity to allow it to measure the automatic actions of the pelvic floor muscles in real-life situations.¹¹11. Bø K, Sherburn M. Evaluation of female pelvic-floor muscle function and strength. Phys Ther. 2005;85(3):269-82.

There is uncertainty about the relationship between obstetric events and pelvic floor injury and about whether women delivering by cesarean section are at lower risk of subsequent urinary incontinence than are women who deliver vaginally.¹²12. Toozs-Hobson P, Balmforth J, Cardozo L, Khullar V, Athanasiou S. The effect of mode of delivery on pelvic floor functional anatomy. Int Urogynecol J Pelvic Floor Dysfunct. 2008;19(3):407-16.−¹⁴14. Boyles SH, Li H, Mori T, Osterweil P, Guise JM. Effect of mode of delivery on the incidence of urinary incontinence in primiparous women. Obstet Gynecol. 2009;113(1):134-41.

OBJECTIVE

The aim of this cross-sectional study was to assess the two-year postpartum prevalence of urinary incontinence and pelvic floor muscle dysfunction among primiparae following cesarean section, and to determine the factors responsible for two-year postpartum urinary incontinence and pelvic floor muscle dysfunction.

METHODS

The Institutional Review Board of the Faculdade de Medicina de Botucatu, Universidade Estadual Paulista (FMB-Unesp), São Paulo, Brazil, granted approval for this study. This was a cross-sectional study including all of the women who delivered between June 1, 2008, and February 28, 2009, and who were eligible for a postpartum interview on urinary incontinence and persistent pelvic floor injury. A total of 832 women were identified using data from the Health Department Registration System.

A simple telephone questionnaire was used to recruit primiparous women who were between 20 and 30 years old when they delivered; delivered at term (by means of either elective cesarean section or spontaneous vaginal childbirth); and delivered an infant with a birth weight lower than 4 kg. The exclusion criteria were previous miscarriage, pelvic or abdominal surgery, previous urogynecological surgery and chronic illnesses such as diabetes mellitus, hypertension, chronic rheumatoid disease or neurological disorders. From these inclusion and exclusion criteria, 355 women were recruited (40.2%).

Using pelvic floor strength, an α of 0.05 and a β of 0.2, the required sample size for this study was 106 women with cesarean section and 106 with vaginal childbirth.¹⁵15. Barbosa AMP, Carvalho LR, Martins AMVC, Calderon IMP, Rudge MVC. Efeito da via de parto sobre a força muscular do assoalho pélvico [The influence of the delivery route on pelvic floor muscle strength] Rev Bras Ginecol Obstet. 2005;27(11):677-82.

Two years postpartum, all of the women were interviewed in person regarding their urinary incontinence symptoms and the prevalence of urinary incontinence before and during the pregnancy and in the two years after the “index birth”. All of the women were questioned by the same research. They were also asked whether they had consulted a physician regarding their urinary incontinence and whether they desired further evaluation and treatment.

The obstetric and maternal data relevant to the “index birth” were retrieved from the hospital records. The following maternal, fetal and obstetric parameters were assessed: maternal age, weight and height; weight gain during pregnancy; gestational age at delivery; delivery method (cesarean section or vaginal childbirth); and birth weight. The body mass index, i.e. the ratio of present weight in kilograms divided by height in meters squared (kg/m²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8.), was also calculated.

A conventional clinical evaluation was then performed, and pelvic floor contraction strength was assessed by means of digital examination, which was performed with the knees semiflexed. A score of between 0 and 3 was given, as described by Amaro et al.¹⁶16. Amaro JL, Gameiro MO, Kawano PR, Padovani CR. Intravaginal electrical stimulation: a randomized, double-blind study on the treatment of mixed urinary incontinence. Acta Obstet Gynecol Scand. 2006;85(5):619-22. We considered digital examination scores of less than 3 to be abnormal.

Vaginal manometry (perineometry) was performed using a vaginal latex-sensor perineometer, with the woman in the same position used for the pelvic floor contraction assessment. Manometric values higher than 33.6 mmHg were considered normal.¹⁵15. Barbosa AMP, Carvalho LR, Martins AMVC, Calderon IMP, Rudge MVC. Efeito da via de parto sobre a força muscular do assoalho pélvico [The influence of the delivery route on pelvic floor muscle strength] Rev Bras Ginecol Obstet. 2005;27(11):677-82. The women answered the Questionnaire for Urinary Incontinence Diagnosis¹⁷17. Bradley CS, Rovner ES, Morgan MA, et al. A new questionnaire for urinary incontinence diagnosis in women: development and testing. Am J Obstet Gynecol. 2005;192(1):66-73. and the International Consultation on Incontinence Questionnaire - Short Form (ICIQ-SF), which had been translated into Portuguese and validated among female Brazilian patients complaining of urinary incontinence.¹⁸18. Tamanini JT, Dambros M, D'Ancona CA, et al. Validação para o português do “International Consultation on Incontinence Questionnaire -- Short Form” (ICIQ-SF) [Validation of the “International Consultation on Incontinence Questionnaire -- Short Form (ICIQ-SF) for Portuguese]. Rev Saude Publica. 2004;38(3):438-44. The questionnaire investigated the following aspects of pregnancy and childbirth: maternal weight gain, newborn weight, whether the mother had entered into partum labor, postpartum complications, involuntary urine loss (under circumstances such as coughing, sneezing, laughing, lifting weights, squatting or walking, and/or when feeling a strong urge to urinate, being in contact with water, hearing running water and being exposed to low temperatures), during pregnancy and the postpartum period.

The data were analyzed using two different methods. Student's t test was used for comparing the means, and the Z test was used for investigating the differences between proportions. The adjusted odds ratios (ORs) and their 95% confidence intervals (95% CIs) were calculated using the Mantel-Haenszel χ²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. test. For the logistic regression analysis, urinary incontinence and pelvic floor muscle dysfunction were used as the reference variables. The statistical calculations were performed using the SPSS 12.0 (Statistical Package for Social Sciences) and SAS 8.02 software programs. The statistical significance level was set at P < 0.05.

RESULTS

The population characteristics showed no significant differences in maternal age, gestational age at delivery, weight gain during pregnancy or birth weight. Two years after delivery, the prevalence of urinary incontinence was 17% following vaginal childbirth and 18.9% following cesarean section. No significant differences were found between the cesarean section and vaginal childbirth groups regarding the incidence of either urinary incontinence or pelvic floor muscle dysfunction (Table 1).

There was an increased risk of subsequent pelvic floor muscle dysfunction with increasing weight gain during pregnancy (OR = 1.3 and 95% CI = 1.1-1.4 for digital palpation; OR = 1.2 and 95% CI = 1.0-1.3 for perineometry) (Table 2).

The patients with body mass indices ≤ 25 kg/m²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. and normal pelvic floor muscle strength two years after delivery were less likely to complain of urinary incontinence (OR = 0.8, 95% CI = 0.7-0.9 and OR = 0.1, 95% CI = 0.03-0.8, respectively). The women with gestational urinary incontinence were more likely to describe urinary incontinence symptoms two years after delivery (OR = 8.6, 95% CI = 3.0-24.3). The delivery method was not a risk factor for urinary incontinence two years after the “index birth” (Table 3).

DISCUSSION

The present study found that cesarean sections did not protect against urinary incontinence two years after childbirth in Brazil, a country in which 40% of deliveries are performed by means of elective cesarean section.¹⁹19. Kilsztajn S, Carmo MS, Machado LC Jr, Lopes ES, Lima LZ. Caesarean sections and maternal mortality in Sao Paulo. Eur J Obstet Gynecol Reprod Biol. 2007;132(1):64-9.

Our results are consistent with those of Viktrup,²⁰20. Viktrup L. The risk of lower urinary tract symptoms five years after the first delivery. Neurourol Urodyn. 2002;21(1):2-29. who followed 278 primiparae for five years postpartum and found no statistically significant associations between first birth via cesarean section and urinary incontinence at follow-up. Zhu et al.²¹21. Zhu L, Lang J, Liu C, et al. Epidemiological study of urge urinary incontinence and risk factors in China. Int Urogynecol J. 2010;21(5):589-93. evaluated the prevalence and risk factors for urge urinary incontinence among adult Chinese women and found that parity and the mode of delivery were not risk factors.

Elective cesarean section seems to have a limited protective effect that appears to weaken with time. Vaginal delivery in itself is neither a sufficient nor a necessary condition for urinary incontinence in most women. By inference, cesarean section is not sufficient to prevent all cases of urinary incontinence.²²22. Dietz HP. Pelvic floor trauma following vaginal delivery. Curr Opin Obstet Gynecol. 2006;18(5):528-37.,²³23. Nygaard I. Urinary incontinence: is cesarean delivery protective? Semin Perinatol. 2006;30(5):267-71. It has been assumed that cesarean section delivery protects against urinary incontinence, and several studies on postpartum and general populations have confirmed this association. However, Herrmann et al.²⁴24. Herrmann V, Scarpa K, Palma PC, Riccetto CZ. Stress urinary incontinence 3 years after pregnancy: correlation to mode of delivery and parity. Int Urogynecol J Pelvic Floor Dysfunct. 2009;20(3):281-8. found no significant correlation between the incidence of stress urinary incontinence and the mode of delivery.

In a longitudinal cohort investigation of urinary incontinence in a postpartum population large enough to examine the effect of delivery methods over time, McArthur et al.²⁵25. MacArthur C, Glazener CM, Wilson PD, et al. Persistent urinary incontinence and delivery mode history: a six-year longitudinal study. BJOG. 2006;113(2):218-24. found that delivery exclusively by means of cesarean section reduced the odds of developing persistent urinary incontinence by half. Even among this group, however, the prevalence of persistent urinary incontinence was still relatively high (14%). This value was quite similar to our results.

Our analysis on first childbirths among 212 women showed that the risk of urinary incontinence two years postpartum was raised considerably by urinary incontinence during pregnancy (OR = 8.6, 95% CI = 3.02-24.32) and that childbirth-induced urinary incontinence was not preventable by cesarean section. In Brazil, cesarean section is far more common than recommended by the World Health Organization and may seem to offer a potential means to prevent urinary incontinence. Our results confirmed the data of Foldspang et al.²⁶26. Foldspang A, Hvidman L, Mommsen S, Nielsen JB. Risk of postpartum urinary incontinence associated with pregnancy and mode of delivery. Acta Obstet Gynecol Scand. 2004;83(10):923-7. and Eason et al.,⁷7. Eason E, Labrecque M, Marcoux S, Mondor M. Effects of carrying a pregnancy and of method of delivery on urinary incontinence: a prospective cohort study. BMC Pregnancy Childbirth. 2004;19;4(1):4. who found that urinary incontinence before delivery roughly doubles the likelihood of urinary incontinence postpartum, regardless of whether the delivery is vaginal or via cesarean section. Occurrences before delivery are an important risk factor for urinary incontinence afterwards and later in life. These protective data confirm that urinary incontinence beginning during pregnancy is neither trivial nor transient. They indicate that there is a significant risk of persistent urinary incontinence, even among women who deliver by cesarean section. Our results also confirm some studies that have found pregnancy-induced incontinence to be one of the strongest predictors of postpartum incontinence, regardless of the delivery route.²⁷27. Heit M, Mudd K, Culligan P. Prevention of childbirth injuries to the pelvic floor. Current Womens Health Rep. 2001;1(1):72-80.,²⁸28. Eason E, Labrecque M, Marcoux S, Mordor M. Effects of carrying a pregnancy and of method of delivery on urinary incontinence: a prospective cohort study. BMC Pregnancy Childbirth. 2004;4(1):4.

The present data, which demonstrate similar pelvic floor muscle dysfunction two years after cesarean section and after vaginal childbirth, suggest that childbirth-induced urinary incontinence is not preventable by elective cesarean section. Identifying women at high risk of delivery-related pelvic floor trauma should be a priority for future research in this field.²²22. Dietz HP. Pelvic floor trauma following vaginal delivery. Curr Opin Obstet Gynecol. 2006;18(5):528-37. The current evidence does not support routine use of elective cesarean section to prevent urinary incontinence, and the delivery mode should continue to be dictated by obstetric considerations. This interpretation of our results is in agreement with Casey et al.,²⁹29. Casey BM, Schaffer JI, Bloom SL, et al. Obstetric antecedents for postpartum pelvic floor dysfunction. Am J Obstet Gynecol. 2005;192(5):1655-62. who reported: “childbirth-induced pelvic floor injury does not appear to us to be easily preventable by modifying obstetric practice.” Even the women with elective cesarean sections (in our population) showed levels of urinary incontinence and pelvic floor muscle dysfunction similar to those of the women who delivered vaginally.

Greater weight gain during pregnancy was associated with an increased risk of postpartum pelvic floor muscle dysfunction (OR = 1.3, 95% CI = 1.1-1.4 and OR = 1.2, 95% CI = 1.08-1.34). In addition, a body mass index ≤ 25 kg/m²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. two years after delivery was a protective factor against urinary incontinence (OR = 0.8, 95% CI = 0.77-0.98), as has also been reported by other recent studies.³⁰30. Rortveit G, Hunskaar S. Urinary incontinence and age at the first and last delivery: the Norwegian HUNT/EPINCONT study. Am J Obstet Gynecol. 2006;195(2):433-8.,³¹31. Cedergren MI. Maternal morbid obesity and the risk of adverse pregnancy outcome. Obstet Gynecol. 2004;103(2):219-24.

Eftekhar et al.²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. found that the prevalence of urinary incontinence was associated with a high birth weight (P = 0.00, χ²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. = 25.5). The effect of high birth weight is seen in the extra weight borne by the lower abdominal organs during pregnancy, in addition to the size of the infant that has to pass through the delivery canal. Our results do not confirm that birth weight has an influence on urinary incontinence two years after delivery, and this was probably because only deliveries with birth weights lower than 4000 g were included in this study.

CONCLUSION

The prevalence of urinary incontinence and pelvic floor muscle dysfunction was unrelated to delivery method, and cesarean section did not protect against urinary incontinence two years after delivery. Urinary incontinence during pregnancy is a crucial precursor of urinary incontinence two years postpartum. Weight gain during pregnancy increased the risk of subsequent pelvic floor muscle dysfunction, while a body mass index ≤ 25 kg/m²2. Eftekhar T, Hajibaratali B, Ramezanzadeh F, Shariat M. Postpartum evaluation of stress urinary incontinence among primiparas. Int J Gynaecol Obstet. 2006;94(2):114-8. two years after delivery prevented urinary incontinence.

Further research on a larger group is needed in order to make definitive statements regarding the effects of delivery method on urinary incontinence and pelvic floor dysfunction two years postpartum.

REFERENCES

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