Discussion
According to results of our study we suggested that fundal pressure at
second stage of labour did not cause an increase in anal sphincter
injury, contrary to expectations. Although the study designs are
different, Cosner et al. stated that the second stage of labour was
longer in the group in which fundal pressure was applied, and the
incidence of third and fourth degree perineal lacerations was higher
than the group without fundal pressure.15 Also our
second stage of labour length was significantly longer in fundal
pressure group. We know that Kristeller maneuver applied commonly in
long lasting deliveries and difference in second stage of labour in our
results is compatible with literature.16, 17 In
another studies, fundal pressure is associated with shortened second
stage and increased risk of severe perineal
lacerations.18, 19 The inconsistency between our
results and Cosner’s pilot study can be explained by uncertainty whether
the accompanying episiotomy was median mediolateral and high rate
(29.4%) of OASI in fundal pressure group.15 In
others, it was not specified whether severe perineal injuries were OASI
or third/fourth degree perineal tears.18, 19
Various methods have been investigated to reduce the risk of perineal
tears during delivery. These methods include perineal massage, manual
perineal support, warm compresses, limited use of episiotomy, and
delayed straining. However the effect of mediolateral episiotomy on OASI
in spontaneous vaginal deliveries is not clear. A recent meta-analysis
concluded that mediolateral episiotomy can reduce OASI and should not be
prevented, especially in nulliparous women.20 In an
endoanal ultrasound study with 60 participants which evaluates impact of
mediolateral episiotomy on incidence of obstetrical anal sphincter
injury, authors suggested that mediolateral episiotomy does not seem to
be protective against clinical or sonographic diagnosed OASIS even when
episiotomy technique is considered.21 In studies
comparing mediolateral episiotomy with medial episiotomy, it is clear
that mediolateral episiotomy has a lower risk of obstetric injury
compared to median episiotomy.20, 22 If an episiotomy
is required, mediolateral episiotomy has been shown to be a protective
intervention for OASI, especially in nulliparous
women.23-25 Also the use of mediolateral episiotomy
has a highly protective effect on the incidence of OASI during operative
vaginal delivery.6 We thought that the application of
liberal mediolateral episiotomy with over 45º from midline might have a
protective effect on the anal sphincter in patients undergoing fundal
pressure in our study.26
There are studies evaluating the effect of the Kristeller maneuver on
the pelvic floor muscles rather than the studies evaluating the effect
on the anal sphincter. Yousef et al., in their study on the effect of
the Kristeller maneuver on pelvic floor muscles, showed that the
application of fundal pressure in the second stage of labour was
associated with more than twice the risk of levator ani muscle avulsion
in women with a first vaginal delivery.27 In our
recent study about pelvic floor damage and fundal pressure Fundal
pressure during the second stage of delivery is associated with a higher
risk of levator ani muscle defect and loss of anterior vaginal wall
support.28 In these study, similar to our study, the
duration of the second stage of labour was significantly longer in the
fundal compression group, and episiotomy was performed more frequently
in the fundal compression group.