Statistical analysis Statistical analysis to compare the two groups at the end of the follow-up period with regard to the primary and secondary outcome measures will be blind, by intention-to-treat, considering loss of follow-up as treatment failure. In such cases, at the end of the follow-up period, the frequency of bowel movement and fecal incontinence will be recorded, as well as the response to other variables, reported at the beginning of the study. The chi-squared test will be used for proportions and the Student t-test for numerical variations with normal distribution (the Bartlett test was used to verify the homogeneity of the variance). The Mann-Whitney test will be used for numerical variables with non-normal distribution. Statistical significance will set at p<0,05. All analysis will be performed using the Epi-Info™, version 6.04d (CDC - Center of Disease Control and Prevention, Atlanta, USA and WHO World Health Organization, Geneva, swirtzerland).