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20-05-2007, 09:26
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Commentary
CMAJ • FEB. 5, 2002; 166 (3) 337
© 2002 Canadian Medical Association or its licensors
There is a growing body of evidence that implicates
childbirth in general, and specific peripartum risk
factors in particular, in postpartum pelvic dysfunction.
1 This pelvic dysfunction results from a combination of
structural damage and neurologic injury that occurs during
labour and, most certainly, during vaginal birth.2,3 This evidence
has sparked a debate among health care professionals
and the public regarding the use of elective cesarean delivery
for the reason of avoiding the discomfort of vaginal
birth and the accompanying postpartum pelvic dysfunction.
When asked to indicate their personal preference for mode
of delivery of a normal, term pregnancy, obstetricians —
both male and female — in large numbers opted for cesarean
delivery.4,5 At the heart of this debate is one of the
central tenets of obstetrics: cesarean delivery involves the
greatest risk for the woman and the child. Alternatively, a
vaginal birth, regardless of how it is achieved, is upheld as
more “natural.”
As part of a larger study examining the effect of perineal
massage on the risk of perineal laceration, Erica Eason and
coauthors6 asked patients to complete, 3 months after birth,
a questionnaire that included questions about the frequency
of involuntary loss of flatus and feces (see page 326). At 3
months 3.1% of the women experienced fecal incontinence,
which occurred at least once daily in 0.3%. Uncontrolled
release of flatus occurred in 25.5% of women, at
least once daily in 2.6%. Anal sphincter injury was associated
with increased rates of both fecal and flatal incontinence.
Flatal incontinence was associated with operative
(forceps-assisted) vaginal delivery when compared with
spontaneous vaginal delivery. Although fecal incontinence
was not associated with instrumental delivery, the women
who had a forceps delivery accompanied by a sphincter injury
all experienced fecal incontinence. The only independent
risk factor for anal incontinence found on multivariate
analysis was forceps delivery.
There are several caveats. Although the authors asked
the women about urinary incontinence before their pregnancy,
they did not enquire about anal incontinence. In a
prospective study of primiparous women we found that
35% experienced flatal incontinence before their pregnancy,
and 3%, fecal incontinence.7 To minimize the effect
of pre-existing conditions on the attribution of peripartum
risk factors, it is most appropriate to include only women
who are asymptomatic before pregnancy.
It is also important to measure the effect of flatal incontinence
on quality of life. The authors conclude that, although
the rate of daily postpartum flatal incontinence was
low, the effect on quality of life was substantial. Unfortunately,
they did not formally measure quality of life. In our
study 28% of women were still experiencing occasional
flatal incontinence 6 months after childbirth.7 No woman,
however, experienced daily fecal incontinence. When
asked to comment on the effect of their condition, none of
the women with flatal incontinence believed that it affected
their daily lives, and only one woman with fecal incontinence
considered the incontinence to be an important
problem.
Recovery from pelvic injury incurred during childbirth
is a gradual process that continues for up to 1 year post partum.
8 The authors risk overestimating the rates of longterm
anal incontinence given their short duration of follow-
up, 3 months. On the other hand, we found that rates
of anal incontinence did not decrease significantly between
6 weeks and 6 months post partum.7 Women whose symptoms
resolve in the short term may experience recurrent
symptoms over the long term, presumably as a consequence
of permanent pelvic injury.9
The finding by Eason and coauthors that cesarean delivery
did not appear to afford protection against anal incontinence
is in conflict with considerable evidence in the literature
supporting a protective effect for cesarean delivery.10,11
The fact that women who underwent cesarean section in
the current study had rates of anal incontinence similar to
those among women who gave birth vaginally may be due
to the inclusion of women who underwent cesarean section
during labour, perhaps after injury to pelvic structures had
occurred. Although cesarean section during labour may not
prevent anal incontinence, elective cesarean section clearly
does.7 Elective cesarean delivery does not decrease pelvic
muscle strength: maximum anal resting and squeeze pressures
are unchanged afterward, as is anal sphincter size.12,13
In our study, there were no cases of flatal incontinence in
the elective cesarean delivery group.7 Cesarean section appears
to afford greater protection against the effects of forceps
delivery than does spontaneous vaginal delivery (ce-
Cesarean section versus forceps-assisted
vaginal birth: It’s time to include pelvic injury
in the risk–benefit equation
ß See related article page 326
Scott A. Farrell
sarean delivery, both elective and during labour, is associated
with lower rates of urinary incontinence11).
The finding by Eason and coauthors that forceps delivery
is an independent risk factor for anal incontinence is in
agreement with an overwhelming body of evidence implicating
forceps delivery as a cause of clinically significant
pelvic floor dysfunction.2,14 Spontaneous vaginal delivery
has been shown to have detrimental effects on both external
striated and internal smooth muscle sphincter function;
forceps delivery, in addition to these detrimental effects,
has been associated with impaired anal canal sensation, further
compromising anal sphincter function.15
The authors recommend that median episiotomy be
avoided and that mediolateral episiotomy be used when
episiotomy is indicated. This recommendation is corroborated
by figures from a large database study of more than
90 000 births that showed that the relative risk of anal
sphincter injury was significantly higher with median episiotomy
than with mediolateral episiotomy (Lynne Mac-
Leod, Dalhousie University: personal communication,
2000). The authors conclude that “our findings are important
in understanding how best to manage the second stage
of labour.” Their conclusion that forceps and episiotomy
should not be used to shorten the second stage of labour is
supported by well-designed studies showing that prolongation
of the second stage does not result in detrimental effects
on pelvic organ function.10,11
Perhaps of greater importance are the implications of
this study for the management of a prolonged labour with
secondary arrest. In this situation the choice is between cesarean
delivery and a trial of forceps. Although cesarean delivery
after labour may not prevent anal incontinence, it almost
certainly will prevent significant anal sphincter injury.
Anal sphincter injury is associated with the highest rates of
impaired anal sphincter function. In this situation, perhaps
cesarean delivery is a better choice.
What are the implications of this growing body of evidence
for obstetric practice? Obstetricians are facing increasing
pressure from patients demanding elective cesarean
delivery.5,16 The assumption that vaginal birth —
particularly if it must be effected with instrumental assistance
— is preferable to cesarean delivery is founded on
immediate peripartum risks, such as maternal hemorrhage,
and does not consider the implications of long-term pelvic
dysfunction.16 Obstetricians have an obligation to reconsider
their assumptions about the relative merits of different
delivery options and to convey the evidence to their patients
in a clear and unbiased manner. Women have a right
to consider the evidence and weigh the potential risks and
benefits, and thereby participate more equally in the decisions
concerning their pregnancy and mode of delivery.
Commentary
CMAJ • FEB. 5, 2002; 166 (3) 337
© 2002 Canadian Medical Association or its licensors
There is a growing body of evidence that implicates
childbirth in general, and specific peripartum risk
factors in particular, in postpartum pelvic dysfunction.
1 This pelvic dysfunction results from a combination of
structural damage and neurologic injury that occurs during
labour and, most certainly, during vaginal birth.2,3 This evidence
has sparked a debate among health care professionals
and the public regarding the use of elective cesarean delivery
for the reason of avoiding the discomfort of vaginal
birth and the accompanying postpartum pelvic dysfunction.
When asked to indicate their personal preference for mode
of delivery of a normal, term pregnancy, obstetricians —
both male and female — in large numbers opted for cesarean
delivery.4,5 At the heart of this debate is one of the
central tenets of obstetrics: cesarean delivery involves the
greatest risk for the woman and the child. Alternatively, a
vaginal birth, regardless of how it is achieved, is upheld as
more “natural.”
As part of a larger study examining the effect of perineal
massage on the risk of perineal laceration, Erica Eason and
coauthors6 asked patients to complete, 3 months after birth,
a questionnaire that included questions about the frequency
of involuntary loss of flatus and feces (see page 326). At 3
months 3.1% of the women experienced fecal incontinence,
which occurred at least once daily in 0.3%. Uncontrolled
release of flatus occurred in 25.5% of women, at
least once daily in 2.6%. Anal sphincter injury was associated
with increased rates of both fecal and flatal incontinence.
Flatal incontinence was associated with operative
(forceps-assisted) vaginal delivery when compared with
spontaneous vaginal delivery. Although fecal incontinence
was not associated with instrumental delivery, the women
who had a forceps delivery accompanied by a sphincter injury
all experienced fecal incontinence. The only independent
risk factor for anal incontinence found on multivariate
analysis was forceps delivery.
There are several caveats. Although the authors asked
the women about urinary incontinence before their pregnancy,
they did not enquire about anal incontinence. In a
prospective study of primiparous women we found that
35% experienced flatal incontinence before their pregnancy,
and 3%, fecal incontinence.7 To minimize the effect
of pre-existing conditions on the attribution of peripartum
risk factors, it is most appropriate to include only women
who are asymptomatic before pregnancy.
It is also important to measure the effect of flatal incontinence
on quality of life. The authors conclude that, although
the rate of daily postpartum flatal incontinence was
low, the effect on quality of life was substantial. Unfortunately,
they did not formally measure quality of life. In our
study 28% of women were still experiencing occasional
flatal incontinence 6 months after childbirth.7 No woman,
however, experienced daily fecal incontinence. When
asked to comment on the effect of their condition, none of
the women with flatal incontinence believed that it affected
their daily lives, and only one woman with fecal incontinence
considered the incontinence to be an important
problem.
Recovery from pelvic injury incurred during childbirth
is a gradual process that continues for up to 1 year post partum.
8 The authors risk overestimating the rates of longterm
anal incontinence given their short duration of follow-
up, 3 months. On the other hand, we found that rates
of anal incontinence did not decrease significantly between
6 weeks and 6 months post partum.7 Women whose symptoms
resolve in the short term may experience recurrent
symptoms over the long term, presumably as a consequence
of permanent pelvic injury.9
The finding by Eason and coauthors that cesarean delivery
did not appear to afford protection against anal incontinence
is in conflict with considerable evidence in the literature
supporting a protective effect for cesarean delivery.10,11
The fact that women who underwent cesarean section in
the current study had rates of anal incontinence similar to
those among women who gave birth vaginally may be due
to the inclusion of women who underwent cesarean section
during labour, perhaps after injury to pelvic structures had
occurred. Although cesarean section during labour may not
prevent anal incontinence, elective cesarean section clearly
does.7 Elective cesarean delivery does not decrease pelvic
muscle strength: maximum anal resting and squeeze pressures
are unchanged afterward, as is anal sphincter size.12,13
In our study, there were no cases of flatal incontinence in
the elective cesarean delivery group.7 Cesarean section appears
to afford greater protection against the effects of forceps
delivery than does spontaneous vaginal delivery (ce-
Cesarean section versus forceps-assisted
vaginal birth: It’s time to include pelvic injury
in the risk–benefit equation
ß See related article page 326
Scott A. Farrell
sarean delivery, both elective and during labour, is associated
with lower rates of urinary incontinence11).
The finding by Eason and coauthors that forceps delivery
is an independent risk factor for anal incontinence is in
agreement with an overwhelming body of evidence implicating
forceps delivery as a cause of clinically significant
pelvic floor dysfunction.2,14 Spontaneous vaginal delivery
has been shown to have detrimental effects on both external
striated and internal smooth muscle sphincter function;
forceps delivery, in addition to these detrimental effects,
has been associated with impaired anal canal sensation, further
compromising anal sphincter function.15
The authors recommend that median episiotomy be
avoided and that mediolateral episiotomy be used when
episiotomy is indicated. This recommendation is corroborated
by figures from a large database study of more than
90 000 births that showed that the relative risk of anal
sphincter injury was significantly higher with median episiotomy
than with mediolateral episiotomy (Lynne Mac-
Leod, Dalhousie University: personal communication,
2000). The authors conclude that “our findings are important
in understanding how best to manage the second stage
of labour.” Their conclusion that forceps and episiotomy
should not be used to shorten the second stage of labour is
supported by well-designed studies showing that prolongation
of the second stage does not result in detrimental effects
on pelvic organ function.10,11
Perhaps of greater importance are the implications of
this study for the management of a prolonged labour with
secondary arrest. In this situation the choice is between cesarean
delivery and a trial of forceps. Although cesarean delivery
after labour may not prevent anal incontinence, it almost
certainly will prevent significant anal sphincter injury.
Anal sphincter injury is associated with the highest rates of
impaired anal sphincter function. In this situation, perhaps
cesarean delivery is a better choice.
What are the implications of this growing body of evidence
for obstetric practice? Obstetricians are facing increasing
pressure from patients demanding elective cesarean
delivery.5,16 The assumption that vaginal birth —
particularly if it must be effected with instrumental assistance
— is preferable to cesarean delivery is founded on
immediate peripartum risks, such as maternal hemorrhage,
and does not consider the implications of long-term pelvic
dysfunction.16 Obstetricians have an obligation to reconsider
their assumptions about the relative merits of different
delivery options and to convey the evidence to their patients
in a clear and unbiased manner. Women have a right
to consider the evidence and weigh the potential risks and
benefits, and thereby participate more equally in the decisions
concerning their pregnancy and mode of delivery.