Perineal Trauma and its Effect on the Pelvic Floor and Urinary Incontinence

Background: High prevalence of urinary incontinence in women is a worldwide problem. Higher incidence of problems with urinary incontinence was observed in women after childbirth. Some studies have found a connection between urinary incontinence and perineal trauma. Aim: To determine the influence of perineal trauma (episiotomy, spontaneous rupture) on the pelvic floor and urinary incontinence. Methods: In search for sources we used the electronic databases Medline, CINAHL, PubMed, Science Direct, Scopus, Medvik, and the electronic search engines Google and Google Scholar. We searched for articles in Czech or English. The following keywords were used: perineal trauma, episiotomy, childbirth, urinary incontinence. A total of 21 studies were found: 1 meta-analysis, 3 systematic reviews, 2 randomized controlled trials, and 15 cohort studies. Results: Women with an intact perineum had a stronger pelvic floor than women with a perineal injury, although they did not differ significantly in the incidence of urinary incontinence. A relationship between urinary incontinence and the extent of a spontaneous injury has not been proved. Episiotomy does not protect the pelvic floor and does not reduce the incidence of urinary incontinence in women after childbirth. Conclusion: Obstetricians and midwives should maximally reduce perineal injuries. No study has yet proven a positive effect of episiotomy on the pelvic floor and a reduction in the incidence of urinary incontinence, therefore episiotomy should be performed in clinical practice only when medically indicated.


INTRODUCTION
Most women incur perineal trauma at delivery (1).The most common spontaneous injury is perineal tearing.Perineal tears can be of varying extent as well as localization.They can occur in the vaginal area, perineal muscles, and anus (2).Tears are classified into four categories (3,4).First-degree tear: laceration is limited to vaginal mucosa and perineal skin.Second-degree tear: laceration extends to perineal muscles, but not the anal sphincter.Third-degree tear: laceration of the anal sphincter 3a) partial tear of the external anal sphincter involving less than 50% thickness 3b) more than 50% tear of the external anal sphincter 3c) internal anal sphincter is torn.Fourth-degree tear: external and internal anal sphincter, and rectal mucosa are torn.
According to Smith et al. (1) first-degree perineal tears occur in 5-18% of vaginal births, whilst second-degree tears occur in 20-38% of births.Extensive lacerations with injuries in the anal sphincter occur in 1-4% women (5,6).Spontaneous injuries, especially extensive ones, can lead to short-term problems and discomfort, such as bleeding, pain, or infection.They can also lead to long-term problems, such as urinary incontinence (7).
To reduce these issues, a routine surgical incision of the perineum, or episiotomy, was introduced in the 20th century (8).During the second stage of labour, the baby's head strains and stretches the woman's pelvic floor, which is then likely to sustain an injury.This may result in urinary incontinence (9).Episiotomy is performed in an effort to reduce the pelvic floor injury and thus prevent issues with incontinence (8).Up to 33% women report postpartum incontinence issues (10).According to a Dutch systematic study (11), urinary incontinence is one of the two main factors that decrease the women's quality of life after childbirth.
Professional literature describes up to seven types of episiotomy, but only three are routinely used in medical practice: median, medio-lateral, and lateral (12).Authors of Czech obstetric textbooks list episiotomy as an obstetrical operation.However, in studies published abroad episiotomy is classified as an injury along with perineal tearing (16,17,18).
We were interested to see how spontaneous tearing and episiotomy affect the pelvic floor and the incidence of urinary incontinence.Our research question is: Does perineal trauma affect the pelvic floor and urinary incontinence in women?Since most specialized articles on the topic are in English, we respected the categorization of perineal injury used abroad, which is why both spontaneous ruptures as well as episiotomy have been included in the present study.

RESEARCH STRATEGY
In search for sources we used the electronic databases Medline, Cinahl, Pub Med, Science Direct, Scopus, Medvik, and the electronic search engines Google and Google Scholar.To gather as many relevant sources as possible, we used both basic and advanced search.In the databases Medline, Cinahl, Pub Med, and Medvik we used advanced search, in the database Science Direct we used expert search.Basic search was used for the search engines Google and Google Scholar.The key words used in foreign databases were: perineal trauma, episiotomy, childbirth, and urinary incontinence.The key words used to search in the Czech databases were: porodní poranění, epiziotomie, porod, and močová inkontinence.To search for sources we used Boolean operators OR and AND.In the review we used articles published in Czech and English.Originally, the plan was to use only meta-analyses, systematic reviews, and randomized controlled studies.However, due to a low number of these studies, cohort studies were later included.We retrieved 87 studies that met our criteria.After excluding duplicate entries, 21 studies were included in the present survey: 1 meta-analysis, 3 systemic reviews, 2 randomized controlled studies, and 15 cohort studies.

LITERATURE REVIEW TEXT
Due to the extent and complexity of the topic, the review has been divided into four parts.The first part brings an overview of studies on urinary incontinence and the pelvic floor muscle strength among women who did not sustain perineal injury (i.e. with intact perineum), and women who suffered perineal injury (episiotomy, tearing).The second part offers an overview of studies by the type of perineal trauma -spontaneous injury (perineal tear), and induced injury (episiotomy).The third part of the present survey analyses the extent of birth injuries.This part of the review presents the effect of individual degrees of the perineal trauma on the incidence of urinary trauma and the pelvic floor.The final part compares the results of routine and restrictive episiotomy and the results of women who underwent episiotomy with a control group.

Perineal injury
An absence of a perineal trauma has a protective effect on the woman's pelvic floor.Two cohort studies used electromyography to assess the pelvic floor muscle strength three (19) and six months (20) after delivery.Both studies confirmed that women who had cesarean delivery and women who had vaginal delivery with intact perineum had more muscle strength than women who incurred spontaneous perineal trauma or underwent episiotomy.Women who had a cesarean or a delivery with intact perineum experienced the fastest regeneration of the pelvic floor (19).In another prospective cohort study (21) women with intact perineum had more pelvic floor muscle strength than women with second-degree perineal laceration six weeks postpartum.Although women without perineal tearing had more pelvic floor muscle strength than women with injury, the occurrence of urinary incontinence three months after delivery was comparable in both groups (19,21), (Table 1).

Type of perineal injury
The type of perineal injury does not significantly influence the pelvic floor strength.Women with episiotomy experienced the greatest weakening of the pelvic floor in all the monitored groups (19), but the results in women three months (19) and half a year (20) postpartum did not differ significantly from women with spontaneous perineal laceration.
The available studies do not offer a definite answer whether episiotomy or spontaneous perineal tearing present a risk factor for the occurrence of urinary incontinence in women after childbirth.
According to an extensive study conducted by Zhu et al. (22), which involved more than 10,000 women, spontaneous perineal injury increased the risk of urinary incontinence both six weeks and six months postpartum.However, the study did not prove that spontaneous perineal injury presents a risk factor for the occurrence of urinary incontinence five (23) or ten (24) years after delivery.Similarly, the overall numbers of spontaneous tearing do not affect the occurrence of stress incontinence (25).
Although episiotomy does not increase the risk of urinary incontinence six weeks postpartum, women who underwent surgical incision of the perineum are at a higher risk of urinary incontinence persisting half a year after delivery (22).In their cohort study, Viktrup et al. (23) found out that if a woman underwent episiotomy during her first delivery, five years later she was more likely to suffer from urinary incontinence.In contrast, according to a cohort study by Altman et al. (24), episiotomy does not increase the risk of stress and urgent incontinence ten years after childbirth.According to Handa et al. (25) the overall number of episiotomies is not related to a higher incidence of stress incontinence (Table 2).Six weeks postpartum women with second-degree laceration had a weaker pelvic floor than women with intact perineum (p = 0.03).Twelve weeks postpartum the two groups did not differ in the incidence of urinary incontinence (p = NS).

Fleming et al.
( Cohort study/102 Vaginal electromyography 36th week of pregnancy, and 6 months postpartum Women after C-section and vaginal birth had a stronger pelvic floor than women with spontaneous rupture and episiotomy.When compared with the pelvic floor muscle strength before childbirth, women with intact perineum experienced the greatest postpartum strengthening of the pelvic floor (p = 0.01).

months postpartum
Primiparae (p < 0.001) and multiparae (p = 0.020) after C-section and women after vaginal birth with intact perineum had more pelvic muscle strength and experienced a faster regeneration of the pelvic floor (primiparae p < 0.001, multiparae p = 0.35) than women with spontaneous rupture, women with third-and fourth-degree laceration, and women with episiotomy.The groups did not differ in the incidence of urinary incontinence (p = NS).

Degree of perineal injury
In the study by Fleming et al. (20) the pelvic floor strength was assessed electromyographically.When comparing the antepartum and postpartum measurements, women with intact perineum had the best muscle function, followed by women with first-degree perineal injury, then second-and third-degree perineal injury.The weakest pelvic floor was reported in women with episiotomy.
Authors of a large cohort study (26) found out that women after vaginal childbirth and multiparous women with first-and second-degree perineal injury are more likely to suffer from stress incontinence one year after delivery.The risk was not higher in primiparous women.According to a cohort study by Altman et al. (24), the degree of perineal injury (no injury, first-and second-degree injury, third-and fourth-degree injury) does not constitute a risk for the development of urgent urinary incontinence ten years after childbirth.
Obstetricians and midwives are concerned about third-and fourth-degree lacerations during delivery, that is lacerations that involve the anal sphincter.Such injuries may result in a number of long-term complications.According to available studies, third-and fourth-degree perineum lacerations do not result in urinary incontinence (26,27,28).Borello-France et al. (27) in their prospective cohort study compared the incidence of urinary incontinence in women with and without the anal sphincter injury.There was no difference in the incidence of urinary incontinence six weeks or six months after childbirth.Other authors' studies also confirm that third-and fourth-degree lacerations do not present a risk factor for urinary incontinence one year (26), four years (28) and five years (23) after delivery.According to a Swiss cohort study (29), women with the anal sphincter rupture did not report a higher incidence of incontinence connected with urgency or physical activity.However, these women reported a more frequent minor leakage "by drops" (Table 3).Spontaneous perineal tearing (OR 0.9; 95% Cl 0.9-1.1)and episiotomies (OR 0.9; 95% Cl 0.3-2.6)did not present risk factors for the incidence of urinary incontinence.Likewise, spontaneous perineal lacerations (OR 0.9; 95% Cl 0.7-1.3)and episiotomies (1.7; 95% Cl 0.5-4.1)did not present risk factors for the incidence of urgent incontinence.The pelvic floor strength in women with episiotomy did not significantly differ from women with spontaneous perineal ruptures (p = NS).Comparing the pelvic floor strength before childbirth, the only group with a decrease in the strength were women with episiotomy (p = 0.0004); in all other groups there was an increase in the pelvic floor strength.Episiotomy presented a risk factor for stress incontinence (OR 2.0; 95% Cl 0.9-4.1).Rupture of the anal sphincter and a minor perineal injury did not present a risk (p = NS).

months postpartum
Women with episiotomy did not significantly differ in the pelvic floor strength and the occurrence of urinary incontinence (p = NS) from women with spontaneous perineal lacerations.
Legend: NS = not significant; OR = odds ratio; Cl = confidence interval First-and second-degree lacerations (OR 0.9; 95% Cl 0.9-1.1)and third-and fourth-degree lacerations (OR 0.9; 95% Cl 0.7-1.4) did not present risk factors for the occurrence of stress incontinence.Likewise, first-and second-degree lacerations (OR 1.0; 95% Cl 0.7-1.3)and third-and fourth-degree lacerations (OR 1.0; 95% Cl 0.9-1.1)did not constitute risk factors for the occurrence of urgent incontinence.Women with the anal sphincter rupture reported a higher incidence of minor urine leakage "by drops" (p = 0.04).They did not differ in the incidence of urinary incontinence as a result of physical activity (p = 0.78) or urgency (p = 0.24) from women without the anal sphincter injury.

Fleming et al. (2003)
Cohort study /102 Vaginal electromyography 36th week of pregnancy, and 6 months postpartum Compared to the pelvic floor muscle strength during pregnancy, the muscles grew stronger after pregnancy in the following order: women with intact perineum, women with C-section, women with first-degree tear, second-degree tear, and women with third-degree tear.The pelvic floor grew weaker in women with episiotomy (p = 0.004).

Cohort study /278
Questionnaire based on the definitions of incontinence according to International Continence Society (ICS)

years after first childbirth
Anal sphincter ruptures and minor perineal injuries did not constitute a risk for the occurrence of urinary incontinence (p = NS).
Legend: NS = not significant; OR = odds ratio; Cl = confidence interval

Episiotomy
As it has been mentioned above, episiotomy results in the weakening of the pelvic floor muscles (20), but it is not evident whether it also leads to a higher incidence of urinary incontinence.According to Viktrup et al. (23), episiotomy performed during first childbirth leads to a higher risk of urinary incontinence five years after delivery.However, two other cohort studies (24,30) did not confirm a relation between urinary incontinence and episiotomy.
Four studies (31,32,33,34) researched whether women with episiotomy differ from women without episiotomy in the incidence of urinary incontinence.There was no difference in the incidence of urinary incontinence in women after puerperium (31) and in the first, second, and sixth week after childbirth (32).
In two studies (32,33) no difference was found three months after delivery, but according to Change et al. (32) women with episiotomy had more frequent problems with urinary incontinence three months postpartum than women without episiotomy.
Articles with the highest level of evidence -one meta-analysis (37), three systematic reviews (35,36,38) and one randomized controlled study (39) -compared the results of restrictive and routine (liberal) episiotomies.However, not one study confirmed that routine episiotomy would lead to a reduction in urinary incontinence in women after childbirth (35,36,37,38,39).
The information on the impact of episiotomy on the pelvic floor and urinary incontinence is summarized in Table 4. Women with episiotomy did not significantly differ from women without episiotomy in the incidence of urinary incontinence in the 1st (p = 0.1324), 2nd (p = 0.2079), and 6th week (p = 0.0889) postpartum.Three weeks postpartum the occurrence of urinary incontinence was higher in women with episiotomy (p = 0.0293).Episiotomy did not prove to be a risk factor for the occurrence of stress (OR 0.9; 95% Cl 0.3-2.6)and urgent (OR 1.7; 95% Cl 0.5-4.1)incontinence.Legend: NS = not significant; OR = odds ratio; Cl = confidence interval; RR = relative risk; SD = standard deviation Legend: NS = not significant; OR = odds ratio; Cl = confidence interval; RR = relative risk; SD = standard deviation

RESULTS
The aim of the present survey was to determine the influence of perineal trauma (episiotomy, spontaneous rupture) on the pelvic floor and urinary incontinence.For this purpose the following research question was formed: Does perineal trauma (spontaneous rupture, episiotomy) affect the pelvic floor and urinary incontinence in women?A total of 21 studies were analysed in the overview.The individual papers differed in evidence (from a meta-analysis to cohort studies), number of respondents (from 68 to 10,098 respondents), and measuring tools -from an inquiry about urinary incontinence to uroflowmetry, and electromyography.
A detailed analysis of the studies showed that some of the results may be misrepresented.For example, we found differences when comparing the results in the study by Chang et al. (32) on urinary incontinence in women with and without episiotomy.In this study the research files were compared four times, but only in one instance there were differences.The data files were not comparable -the study examined 188 women with episiotomy, and only 55 women without episiotomy.Furthermore, in both groups there were women with spontaneous perineal injury (first-to fourth-degree lacerations), but the percentage is not stated in the study.Viktrup et al. (23) named episiotomy performed during first delivery as a risk factor for the occurrence of urinary incontinence five years after childbirth.The conclusions were based on the injuries sustained during first delivery, but more than half of the respondents gave two births.During second delivery 7 women underwent vacuum extraction, 25 women underwent episiotomy, and 5 suffered the anal sphincter tearing, which may have affected the occurrence of urinary incontinence in these women.For instance, according to Fritel et al. (27), third-degree perineal laceration is not a risk factor for urinary incontinence, but only 4 women out of 370 in the data file suffered third-degree perineal tearing.
As emerged from the analysis of the retrieved studies, the absence of perineal trauma has a protective effect on the woman's pelvic floor.Women with intact perineum experience a faster recovery of the pelvic floor.Nevertheless, women with intact perineum did not significantly differ in the incidence of urinary incontinence from women with perineal trauma three months postpartum.The survey unequivocally confirms that routine episiotomy does not protect the pelvic floor and does not reduce the incidence of urinary incontinence after delivery.Quite the contrary, women with episiotomy experience the most substantial weakening of the pelvic floor muscles.It was not possible to ascertain whether the type and extent of birth trauma have a significant influence on urinary incontinence after delivery.
The present article is a literature review that has its methodological limits.In order to gain results relevant for clinical application, it would be advisable to conduct another research in the form of a systematic review.

CONCLUSION
Perineal trauma during delivery is a much discussed issue.There are those who advocate timely and preventive episiotomy, and those who view episiotomy as the last resort.Professional care for women during childbirth requires obstetricians and midwives to adopt an individual approach during the first and second stage of labour in order to minimise perineal trauma.The above presented data do not give evidence that episiotomy protects the woman's pelvic floor or reduces the incidence of urinary incontinence.Consequently, episiotomy should be used in clinical practice only in clearly indicated cases.

Fleming
episiotomy did not differ in the incidence of urinary incontinence (p = NS), the pelvic floor muscle strength, and the results of the urodynamic examination (p = NS) from women with liberal episiotomy.Hartmann et al. (2005)Routine episiotomies do not protect women from urinary incontinence.

Table 1
Urinary incontinence and the pelvic floor muscle strength in women with intact perineum and women with perineal injury

Table 2
Urinary incontinence and the pelvic floor strength in women with perineal tearing and episiotomy

Table 3
The pelvic floor and urinary incontinence in women with different degrees of perineal tearing

Table 4
The pelvic floor and urinary incontinence in women with episiotomy