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deliveries with a rigid cup as compared to 29.4%
of deliveries with a soft cup [29]. The same group
of investigators showed that the number of traction pulls was not associated with the risk of levator ani avulsion [30].
The effects of these forces directly on the cervix and vaginal musculature are not described in
literature, making this a potential area for future
research.
4.5 Episiotomy (Table4.2)
An episiotomy, surgical enlargement of the vaginal introitus by an incision of the perineum, was
rst described in the 1740s but did not become
widely used until the twentieth century. At that
time, it was believed that childbirth was a pathologic process and could be shortened with the use
of an episiotomy. From the 1970s to 1990s, episiotomies were commonly performed on all
females during the second stage of labor as it was
thought to decrease perineal trauma, pelvic oor
dysfunction and prolapse, urinary and fecal
incontinence, and sexual dysfunction. In 2006,
the American College of Obstetricians and
Gynecologists published a recommendation
against the use of routine episiotomy due to lack
of evidence showing maternal or fetal benet. To
date, there is still insufcient objective evidencebased criteria to dene the indications for use of
episiotomy in obstetric practice, and the recommendation remains to practice restricted use of
episiotomy based on clinical judgment [31]. In
2012, the rate of episiotomy in childbirth was
12%, decreased from 33% in 2000. While the
rate of episiotomy decreased, the rates of obstetric anal sphincter injury (OASI) decreased 1.5%,
but there was a 7.6% increase in OASI in the setting of operative vaginal delivery [26]. In a review
of 2,226,170 deliveries between 2006 and 2012
at over 5000 hospitals, Friedman etal. demonstrated that white race and commercial insurance
were associated with higher rates of episiotomy
while delivery in a rural or academic center was
associated with lower rates of episiotomy use
[27]. Additional studies on episiotomy use have
revealed that private practitioners have a two- to
fourfold increased use as opposed to trainees,
academic faculty, and midwives [27, 32, 33].
4.5.1 Mediolateral Episiotomy
Mediolateral episiotomy, one in which the incision extends from the introitus down at a 45°
angle, is the preferred type of episiotomy performed in Europe and is recommended over the
midline episiotomy in “Intrapartum care for a
positive childbirth experience” published by the
World Health Organization (Fig. 4.8). In 2008,
the rst large cohort study investigating the rate
of obstetric anal sphincter injuries in operative
deliveries was published using the Dutch National
Obstetric Database. This study which included
21,254 women delivered via vacuum extraction
and 7478 women delivered with forceps demonstrated a 0.11 OR for OASI with mediolateral
episiotomy in vacuum extraction and 0.08in forceps deliveries [34]. A similar result was found in
a study by Gurol-Urganci, which included 1.2
million women and demonstrated a three times
lower incidence of OASIS with the use of mediolateral episiotomy in nulliparous women undergoing operative vaginal delivery (OR 1.89 for
vacuum extraction without episiotomy; OR 6.53
Table 4.2 Types of episiotomies
Episiotomy Description Advantages Disadvantages
Midline Incision extends
downward at 0–25°
angle
Mediolateral Incision extends
from introitus at 45°
angle
In select situations may
facilitate delivery of
fetal head
Questionable lower rate
of OASIS
Independent risk factor for third- or
fourth-degree laceration; increased risk of
bleeding, infection, extension of incision,
postpartum pain, and dyspareunia compared
to no episiotomy
Increased risk of bleeding, infection,
extension of incision, postpartum pain, and
dyspareunia compared to no episiotomy
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Fig. 4.8 Episiotomies
S. White et al.
eral
for forceps delivery without episiotomy) [35].
Another Dutch cohort study in 2018 demonstrated a 14.0% rate of OASI in women who
underwent a vacuum extraction without an episiotomy compared to a 2.5% rate in women who
did receive an episiotomy. In this study, the rate
of mediolateral episiotomy was 87.3%, which
suggests a protective effect of episiotomy. Similar
ndings were demonstrated in women who had
forceps deliveries (26.7% rate of OASI without
episiotomy compared to 3.4% with episiotomy)
and in multiparous women [36]. To date, no randomized control trials have been performed to
validate these ndings.
Angle of the episiotomy is also an important
consideration and factor in OASI.The mediolateral episiotomy ideally starts at the 6 o’clock
position on the posterior fourchette and angles
away from the midline. However, due to signicant distortion of the perineum during childbirth,
the correct starting location and angle can be difcult to estimate. A study performed by Kalis
et al. investigated the difference between the
angle of episiotomy cut during crowning of the
fetal head and the suture angle of the episiotomy
after childbirth. A 40° angle pre- marked episiot-
omy resulted in a 22° suture angle, while a 60°
pre-marked episiotomy resulted in a 45° suture
angle [37]. An Irish study looking at mediolateral
episiotomies revealed that the rate of OASI was
10% with a 25° suture angle but that the risk
reduced by 50% for every 6° that the episiotomy
was angled away from midline; this rate ultimately decreased to 0.5% with a 45° suture angle
[38]. A Norwegian study revealed similar ndings but did show that a 90° suture angle was
associated with a ninefold increased incidence of
OASIS [39]. Based on these ndings, the Royal
College of Obstetricians and Gynecologists as
well as the society of Obstetricians and
Gynecologists of Canada now recommend a 60°
cutting angle when making mediolateral
episiotomies.
When performing a mediolateral episiotomy,
the direction of the incision depends on the handedness of the provider; a right-handed provider
will incise from the posterior fourchette towards
the patient’s left ischial tuberosity. The incision
involves the vaginal epithelium, transverse perineal and bulbocavernosus muscles, and perineal
skin. A large incision may also expose the adipose tissue within the ischiorectal fossa. If
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needed, the incision can be extended through the
levator ani to provide additional space needed
during delivery [40].
Following delivery, a rectal exam should be
performed to evaluate for potential anal sphincter
injury. Repair of a mediolateral episiotomy otherwise occurs in a fashion similar to the repair of
other vaginal lacerations. Prior to re-approximation of the vaginal epithelium, the bulbocavernosus and the transverse perineal muscles must be
re-approximated. Due to more surface area on the
lateral aspect of the incision, larger lateral suture
bites must be taken. The remainder of the repair
occurs in a standard fashion. While interrupted
sutures have been described in episiotomy repair,
continuous repairs are associated with less pain
postpartum, less analgesia use, and a lower risk
of needing suture material removed postpartum
and are therefore recommend by the American
College of Obstetricians and Gynecologists. Care
should be taken not to place excessive tension on
the tissue, which can lead to tissue strangulation.
Synthetic absorbable sutures are recommended
for repair and are associated with less pain up to
3 days postpartum and less analgesia use up to
10 days postpartum. However, women with
absorbable synthetic suture are more likely to
require removal of unabsorbed suture material
postpartum (RR 1.81; 95% CI, 1.46–2.24) [31].
Nonabsorbable sutures should be avoided for episiotomy repair.
4.5.2 Midline Episiotomy
Midline episiotomy, one in which the episiotomy
extends downwards at 0–25° of the sagittal plane,
is the most commonly used episiotomy in the
United States (Fig.4.8). Despite this, it is known
that midline episiotomies are an independent risk
factor for third- or fourth-degree perineal lacerations. Shiono et al. studied 24,114 women and
found that women with midline episiotomies
were almost 50 times more likely to have a thirdor fourth-degree perineal laceration compared to
those who did not undergo episiotomy. After
adjusting for use of forceps, occiput posterior and
occiput transverse presentations, small pelvic
outlet measurements, lower maternal prepregnancy weights, and fetal weight, midline episiotomy was associated with a 4.2-fold increased risk
of laceration in primiparous women and a 12.8fold increased risk in multiparous women [41].
Though this study was performed in 1990, additional more contemporary studies have demonstrated similar ndings. A study performed by
Kudish etal. investigated 33,842 vaginal deliveries between 1996 and 2003 and demonstrated
that nulliparous women who had a midline episiotomy were 4.5 times more likely to have OASI
compared to those who did not have an episiotomy. Meanwhile, multiparous females were 14.6
times more likely to have OASI with midline episiotomy. Similarly, operative vaginal delivery
with episiotomy was associated with a greater
likelihood of having OASI in both nulliparous
and multiparous females, with multiparous
females at a greater risk than nulliparous females
[42]. Even if the laceration spares the anal sphincter, midline episiotomy was found to increase the
length of perineal lacerations by an average of
3cm in a study performed by Nager etal. [43].
To perform a midline episiotomy, the perineum
is incised vertically at the 6 o’clock position
starting at the introitus. The incision is directed
internally with the intent to minimize the amount
of perineal skin incised. The length of the incision varies depending on the clinical situation
with the goal to release any tissue that may be
restricting the delivery of the fetal head. The layers of tissue incised in a midline episiotomy
include vaginal epithelium, perineal body, and
junction of the perineal body with the bulbocavernosus muscle.
Repair of a midline episiotomy is performed
in a similar fashion to a second-degree perineal
laceration repair.
4.5.3 Complications
Complications of episiotomy have been reported
to include extension of the perineal incision,
bleeding, infection, breakdown of the episiotomy,
postpartum pain, and dyspareunia. However,
with the exception of perineal laceration exten-
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sion, data is conicting regarding these long-term
complications. In a meta-analysis of 22 studies,
women with a third- or fourth-degree perineal
laceration were 3.69 times more likely to have
had an episiotomy performed during delivery
[44]. In a randomized control trial in Colombia in
2008, nulliparous females who received routine
midline episiotomy were more likely to have a
third-degree laceration compared to females who
did not have an episiotomy [45]. In contrast,
severe perineal lacerations may be decreased
with mediolateral episiotomies compared to midline episiotomies. The Collaborative Perinatal
Project demonstrated a decreased adjusted odds
ratio for OASI with mediolateral episiotomies in
primiparous females [41]. A Cochrane review in
2017 did not nd any increased risk in blood loss
at delivery, perineal infection, moderate or severe
perineal pain, long- term dyspareunia, urinary
incontinence, or genital prolapse in women who
received routine episiotomy versus those who
received selective episiotomy [46]. However,
House etal. demonstrated a statistically signicant increase in pain of postpartum day 3 with
routine use of episiotomy compared to restricted
use [47], and likewise, a prospective cohort study
involving 519 females found signicantly higher
rates of perineal pain and dyspareunia at 3months
postpartum in those who received a mediolateral
episiotomy compared to those who did not [48].
In a study focused only on midline episiotomies,
no increased postpartum pain was found in
women who received episiotomy versus those
who did not [49].
4.6 Pelvic Floor inRelation
toEpisiotomy
While vaginal delivery is a known risk factor for
pelvic oor dysfunction, the relation of episiotomy to this dysfunction is not well known.
Multiple studies performed in the early 1990s
demonstrated that there is a general decline in
perineal function regardless of the degree of perineal damage obtained during childbirth and that
this decline in function was most notable following a primigravid birth. Similarly, Rockner etal.
demonstrated that women who had a mediolateral episiotomy had a 33% loss in muscle function compared to a 20% loss in women who did
not receive an episiotomy [50]. Fleming et al.
investigated the effects of midline episiotomy on
perineal muscle strength. In the study, pregnant
females had their perineal muscle strength and
endurance tested both antepartum and postpartum. Antenatally, women who eventually received
an episiotomy were found to have the highest
peak muscle strength and endurance. When comparing women who had intact perinea, episiotomies, rst-degree lacerations, second-degree
lacerations, and cesarean sections, women who
had episiotomies had the worst perineal muscle
performance postpartum and were the only group
of women who had a decline in postpartum muscle strength when compared to antepartum muscle strength [51]. Contrasting these ndings, a
secondary analysis of the Mothers’ Outcomes
After Delivery study found that history of episiotomy was not associated with pelvic oor disorders 5–10 years following delivery; the relative
odds of prolapse was the same among women
with a history of no episiotomies, one episiotomy, or multiple episiotomies. Women with a
history of multiple spontaneous lacerations were
signicantly more likely to have stage 2 or greater
prolapse when compared with those who had
none or one spontaneous laceration. This analysis
was supportive of newer evidence that levator ani
avulsion plays a role in the development of pelvic
oor dysfunction and that spontaneous laceration
is a proxy for excessive levator ani stretch and
avulsion during childbirth. With this theory, episiotomy would relieve this stretch and therefore
potentially preserve levator ani anatomy and
function later in life [52]. Furthering this theory,
Oliveira and colleagues created a biomechanical
model to assess the distribution of stress and
damage on the pelvic oor muscles that occurs in
various obstetrical situations. The model included
the levator ani and coccygeus muscles, the surrounding support structures, the pubic bone, and
the fetal head in the occiput anterior position with
initial head exion to present and maintain the
smallest head diameter during the simulated
delivery. An intact perineum was compared to
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three lengths of episiotomy (10, 20, and 30mm)
performed at three angles (30, 45, and 60°). In
this model, the pelvic oor muscles, specically
the pubovisceral component of the levator ani,
were subject to signicant stretch and strain and
episiotomy was found to be protective against
such damage. In all simulated deliveries, the
maximum value of stress on the muscle was
where the opening of the episiotomy ended, and
in the intact perineum, the stress was distributed
at the insertion points of the rectal area of the
levator ani. In the model, the angle of the episiotomy was found to affect the amount of force
experienced by the tissue with the 30° angle producing the least amount of tissue damage.
Similarly, the length of the episiotomy was also
found to be inversely proportional to the amount
of force the muscle experienced with the 30mm
incision having the least amount of force needed
for delivery. Taken altogether, a 30mm episiotomy at 30° was found to be most protective to the
pelvic oor musculature. The peak force needed
for delivery with this episiotomy was found to be
100.9N, while the peak force needed for delivery
without episiotomy was 211.0N.This is suggestive that the force needed for delivery in the setting of an episiotomy is less likely to cause
avulsion of the levator ani from the pubic bone
when compared to a delivery without an episiotomy [53]. To conrm and expand these ndings,
Oliveira and colleagues created additional models to evaluate the effects of vaginal delivery and
episiotomy on the pelvic oor musculature and
the development of pelvic organ prolapse. In
these models, the same angles and lengths of episiotomy were tested as in previous models.
Again, a 30 mm episiotomy cut at a 30° angle
was found to be protective against pelvic oor
muscle damage when compared to a vaginal
delivery without episiotomy and the other episiotomies evaluated. Furthermore, damaged pelvic
oor musculature was more like to be associated
with a larger levator hiatus and inability to contract the pelvic openings, decreased ability to
elevate the pelvic oor musculature with voluntary contraction, and increased mobility between
the bladder neck and pubic symphysis, suggestive of increased risk of stress urinary inconti-
nence [54]. These results stand in direct contrast
to those found by Fleming etal., which demonstrated weaker pelvic oor musculature in the
setting of episiotomy. However, Oliveira’s models demonstrated tissue strength immediately
postpartum, and it is possible that the tissue
strength is lost after healing of the episiotomy
repair.
4.7 Cesarean Delivery
Cesarean section, rst described in ancient Rome,
is now performed for approximately 32% of
births in North America. While the rate varies
greatly among countries due to available
resources, the global rate of cesarean sections is
approximately 21%. However, in countries such
as Brazil, the rate is between 80 and 90% due to
requests for elective cesarean sections. In the
United States, it is estimated that the elective
cesarean rate due to maternal request is 2.5%.
Indications for cesarean section include fetal distress, fetal malpresentation, failed progression of
labor, failed induction of labor, history of prior
cesarean sections, and fetal or maternal contraindications to labor. The American College of
Obstetricians and Gynecologists recommends
proceeding with cesarean based on maternal
request only after counseling about the risks of
cesarean section and the increased risks of placenta previa, placenta accreta, and need for hysterectomy with subsequent cesareans.
4.7.1 Transverse Skin Incisions
A Pfannenstiel incision is the incision most commonly used in contemporary cesarean sections
(Fig. 4.9). This incision is made 2–3 cm above
the pubic symphysis in a curvilinear fashion to
follow the lines of Langerhans along the abdomen. Care should be taken when extending this
incision into the subcutaneous tissue to avoid lateral extension, which may transect the supercial
epigastric arteries. Following dissection through
the skin and subcutaneous tissue, the anterior rectus fascia is sharply incised with a scalpel, and
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the incision is extended laterally with curved
Mayo scissors or a scalpel. The fascia is then dissected off the underlying rectus muscle with a
combination of sharp and blunt dissection, taking
care to ligate any perforating vessels. The peritoneum can then be entered between the rectus
muscle bellies, offering access to the anterior
uterine surface. Pfannenstiel incisions are associated with better cosmesis and less postoperative
pain when compared to midline vertical incisions
but, due to more dissection to reach the uterus,
are associated with a slightly longer operative
time [55, 56].
The Joel-Cohen incision is a transverse incision made 2–3 cm above where a Pfannenstiel
incision would traditionally be made; this incision is linear rather than curvilinear in nature.
When performing a cesarean with a Joel-Cohen
incision, blunt dissection can be used once the
fascia is transected, resulting in a faster operating
time. However, there are no other maternal or
Fig. 4.9 Cesarean skin
incisions
fetal benets other than speed, and the surgical
steps performed are similar to those taken with a
Pfannenstiel incision [56].
4.7.2 Vertical Skin Incision
The midline vertical incision was the skin incision historically used secondary to speed and
ease of entry into the peritoneal cavity (Fig.4.9).
With this incision, a vertical skin incision is made
from below the umbilicus to just above the pubic
symphysis; if needed, the incision can be
extended cephalad around the umbilicus. The
incision is carried down sharply to the level of the
rectus muscle sheath, which is then incised
sharply and extended both cephalad and caudad.
The fascial edge closest to midline is then grasped
and dissected bluntly and sharply off the underlying rectus muscle. The peritoneal cavity can then
be entered to expose the uterus.
Midline
vertical
Joel cohen
Pfannenstiel
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While the primary skin incision is no longer
used, a midline vertical incision is associated
with decreased blood loss as the supercial epigastric arteries and supercial circumex iliac
veins are out of the operative eld. This incision
also allows for increased access to the uterus in
situations where a technically difcult surgery is
anticipated. However, midline vertical incisions
are also associated with poorer cosmesis,
increased postoperative pain, infection, wound
dehiscence, and hernia formation [55, 56].
4.7.3 Uterine Entry
There are three types of hysterotomy that are traditionally used during cesarean section: low
transverse, low vertical, and classical (Fig.4.10).
The type of incision used is determined by gestational age at delivery, width of the lower uterine
segment, lie of the fetus, uterine anomalies, and
placental location in the event of a morbidly
adherent placenta. Furthermore, low transverse
uterine incisions can also be extended by the
operator to make a “J” or “T” incision if needed
for delivery of the fetus [55, 56].
The low transverse hysterotomy is made in the
lower uterine segment and is used in 90% of all
cesarean sections. The incision is made approximately 2–3cm above the upper edge of the vesicouterine fold in the noncontractile portion of the
uterus. When making the hysterotomy, it is advisable to leave the membranes intact to avoid lacer-
ating the fetus. Extending of the hysterotomy can
be done either bluntly or sharply with scissors. If
sharply extended, bandage scissors are used to
extend the hysterotomy laterally and then slightly
upward. If performed bluntly, the hysterotomy
can be extended either in a transverse or in a
cephalad- caudad fashion [55, 56]. A study performed by Magann et al. showed that sharp
extension of hysterotomy was associated with
increased estimated blood loss, change in hematocrit, postpartum hemorrhage, and inadvertent
lateral extension of the hysterotomy as compared
to blunt extension [57]. In a study of 800 women,
Cromi etal. demonstrated that a transverse extension of the hysterotomy was associated with
higher rate of unintended lateral extension and
increased risk of blood loss >1500 mL when
compared to a cephalad-caudad extension [58].
In approximately 1–2% of cesarean sections,
the incision is extended vertically by the surgeon
to make a “J” or “T” incision. A T extension is
made in the midline of the hysterotomy, whereas
a J extension is made at the lateral aspect. These
intentional extensions are typically needed for
fetal malpresentation, difcult fetal extraction, or
a poorly developed lower uterine segment and are
associated with increased blood loss, broad ligament hematoma formation, and uterine artery
laceration when compared to low transverse hysterotomy without extensions [56]. Furthermore,
if the vertical extension involves the contractile
portion of the uterus, future attempts at labor may
be contraindicated. In a review of patients who
Fig. 4.10 Uterine cesarean incisions. Depicted left to right: low transverse incision, J incision, classical incision, T
incision
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delivered between 1988 and 1994 at the Ohio
State University that required one of these extensions, these deliveries were associated with
increased blood loss, uterine extension, broad
ligament hematoma, cervical laceration, uterine
artery laceration, and longer hospital stay [59].
The low vertical hysterotomy is made parallel
to the long axis of the uterus but remains in the
noncontractile portion of the uterus. Technical
aspects of making the hysterotomy remain the
same as a low transverse hysterotomy.
A classical hysterotomy is one in which the
incision is made parallel to the long axis of the
uterus through the contractile portion of the myometrium. This incision is used when the lower
uterine segment has not fully developed, in cases
of fetal malpresentation such as transverse back
down lie, and in the setting of uterine anomalies,
such as uterine broids, which preclude a low
transverse hysterotomy [55, 56]. In an analysis of
the Maternal-Fetal Medicine Network database
of women delivered via cesarean with a known
hysterotomy, 4.3% received a classical hysterotomy. The incidence of a classical hysterectomy
peaked between 24 0/7days and 25 6/7days, and
the likelihood of classical hysterectomy also
increased with small for gestational age and noncephalic presentation [60].
While a classical hysterectomy must be closed
in multiple layers to ensure adequate tensile
strength and hemostasis, there has been debate as
to the optimal manner to close a low transverse
hysterotomy. A Cochrane review performed in
2014 looked at the material and technique used
for hysterotomy closure as well as single- versus
double-layer closure with the primary outcome
of febrile morbidity and secondary outcomes that
included postoperative pain, blood loss, need for
transfusion, wound complication or infection,
duration of surgery, thromboembolic event, and
complications with future pregnancies or surgery.
A single trial was identied in which chromic
catgut was compared to polyglactin-910, and closure with catgut was associated with reduction in
the need for blood transfusion and complications
requiring re-laparotomy. Nineteen studies compared single- versus double-layer closure of the
hysterotomy. There was no signicant difference
in both primary and secondary outcomes with
either closure technique [61]. A second large
meta-analysis was also performed in 2014
reviewing single- versus double-layer closure.
This review found that both types of closure had
similar short-term maternal outcomes, but singlelayer closure was associated with shorter operative time. Single-layer closure and locked
rst-layer closure were also associated with less
residual myometrial thickness on future ultrasound studies. However, there was no signicant
difference in the risk of uterine rupture between
single- and double-layer closure. Based on the
ndings, the authors stated that there was not a
preferable manner in which to close the hysterotomy [62]. A more recent meta-analysis performed in 2017 also found that single- versus
double-layer closures had similar risks of uterine
scar defects, including dehiscence and rupture
[63]. However, in a randomized trial of 81
women, double-layer closure with an unlocked
rst layer was associated with a signicantly
thicker residual myometrial thickness when compared to a single-layer closure. A double- layer
closure with a locked rst layer was not signicantly different than a single-layer closure [64].
4.7.4 Fascial Closure
Adequate fascial closure is crucial to prevent the
development of hernias and ensure proper postoperative healing. Ideally, the fascia would be
closed in a manner that would provide elastic and
tensile strength similar to that of fascia itself and
would allow for or promote healing without
increasing the risk of infection. Synthetic monolament sutures were designed with this in mind
but still are associated with an infection rate of
9–14% and lose at least 75% of their tensile
strength by 6 weeks. Synthetic fast absorbable
sutures, such as Vicryl, are commonly used for
fascial closure but only provide tensile strength
for 3–4weeks, leaving the wound at risk for incision, hernia formation, or dehiscence, and indeed
this nding was seen in the INSECT trial. The
hernia formation rate was 16% with the use of
Vicryl compared to 8% with the use of PDS [65].
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However, this nding was not seen in other
reviews. In a large meta-analysis of 55 studies,
Patel etal. found no difference in hernia formation when looking at absorbable vs. nonabsorbable suture, slow versus fast absorbable suture,
mass versus layered closure, and interrupted versus continuous closure. Similarly, there was no
difference found in the rate of wound infection or
wound dehiscence when these measures were
investigated. Absorbable sutures may decrease
the risk of postoperative stula formation, but
this is an issue infrequently seen in the obstetric
population [66]. The MATCH review, another
meta-analysis of 23 studies, also found that suture
material did not affect the rate of hernia formation following laparotomy incision [67]. Patel did
nd that the use of monolament suture may
decrease the risk of hernia formation following a
laparotomy incision and that absorbable sutures
may decrease the risk of postoperative stula formation, but this is an issue infrequently seen in
the obstetric population [66]. As infection has
also been linked to the development of incisional
hernias, research has been done to determine if
using antibiotic-impregnated suture may decrease
hernia formation. A study by Justinger etal. did
demonstrate a decrease in wound infections with
the use of triclosan-coated Vicryl compared to
PDS suture in elective laparotomy but did not
nd a difference in hernia formation [68].
Multiple other studies in general surgery and
colorectal literature have conrmed a decrease in
surgical site infections with the use of triclosansoaked suture, but none have commented on the
formation of hernias. As data remains limited on
the use of antibiotic-coated suture in obstetric literature, it is unclear if the additional costs associated with the suture are warranted in all patients;
however, these could be considered in patients
deemed high risk for hernia formation or
infection.
Traditionally, when closing fascia, sutures are
placed 10–15mm apart and 10–15mm from the
fascial edge as described by Descoux et al. in
1993 [69]. However, the STITCH trial found that
small bites, dened as 5 mm apart and 5 mm
from the edge of the fascia, were associated with
signicantly fewer incisional hernias when com-
pared to traditional spacing. This technique, as it
contradicts traditional teaching, does warrant further investigation before becoming used in a
widespread manner [70].
4.7.5 Skin Closure
When it comes to skin closure following cesarean
delivery, there have been many studies comparing options for skin closure, including sutures,
staples, and glue. Most randomized controlled
trials have compared absorbable sutures with
nonabsorbable metal staple closure. A metaanalysis of 12 randomized controlled trials,
including 3112 women, reported fewer wound
complications, particularly wound separation
with suture closure [71]. In addition, suture was
associated with improved cosmesis and increased
patient satisfaction [72]. Based on this large volume of level 1 data, the absorbable suture is currently considered the gold standard for skin
closure at the time of cesarean delivery [73].
4.8 Uterine Changes
Postdelivery
Following delivery, the uterus involutes to return
to a nonpregnant size. In a prospective study by
Mulic-Lutvica using ultrasound to evaluate postpartum uterine changes, the maximum anteroposterior diameter of the uterus decreased from
92.0 mm on postpartum day 1 to 38.9 mm on
postpartum day 56. Similarly, the maximum
anteroposterior diameter of the uterine cavity
decreased from 15.8mm on postpartum day 1 to
4.0mm on day 56. The anteroposterior diameter
did, however, increase between days 7 and 14
postpartum [74]. Likewise, a study performed by
Negishi etal. also demonstrated decreasing uterine sizes during the puerperium. In this study, the
length of the uterus 1 month postpartum was
found to be 79.3 and 70.3mm at 3months postpartum. These measurements were larger in
women who had had cesarean sections compared
to those who had undergone vaginal delivery.
Increased maternal parity was also associated
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with increased uterine size, while breastfeeding
80% or more per day was associated with a
smaller uterine length and width compared to
women who breastfed 20% or less [75]. Cesarean
section also appears to affect the position of the
uterus postpartum. A study by Kaelin Agten etal.
demonstrated that patients who had undergone
cesarean section were more likely to have an
increased exion angle compared to those who
had undergone vaginal delivery, placing the
uterus in a more retroexed position [76].
Furthermore, according to Ryo et al., uterine
exion increases with the number of cesarean
deliveries, and exion was found to change after
cesarean delivery in 41.6% of patients. This study
also found that changes in uterine exion were
more frequently seen in women who had cesarean scar defects compared to those who did not
have such defects. Based on their ndings, these
authors believe that the uterine exion occurs as
a result of poor healing of the scar and subsequent failure of restoration of the anterior uterine
segment [77].
Following cesarean deliveries, some patients
develop a niche or cesarean scar defect, which
can be detected on ultrasound. It is described as a
triangular anechoic area at the presumed location
of the hysterotomy. However, the exact sonographic characteristics needed to dene a niche
are currently unclear with multiple denitions or
ndings used. A meta-analysis by Bij de Vaate
found a prevalence of a niche in 24–70% of
patients with a history of one or more cesareans
when using transvaginal ultrasonography; using
sonohysterography, the prevalence varied from
56 to 84%. Suspected risk factors for the development of niches include single-layer myometrial closure, history of multiple cesareans, and a
retroexed uterus; however, the included studies
did not investigate identical risk factors and some
risk factors are known to be related. Therefore,
the determination of exact risk factors was inconclusive, and it remains unclear how niches
develop [78]. A study from the Czech Republic
found that when comparing females who had a
single-layer closure of the hysterotomy versus
double-layer closure, a higher proportion of
niches were seen with single-layer closure.
Furthermore, the defects in the single-layer closure were wider, and the residual myometrial
thickness was thinner [79]. Bij etal. hypothesized
based on the meta-analysis that a thinner myometrium, such as that in the lower uterine segment,
is less vascularized and that other factors, such as
uterine exion, may obstruct blood ow to the
uterine segment, impede healing, and lead to the
formation of a niche [78]. However, as mentioned
earlier, other studies suggest that perhaps the
niche itself leads to retroexion [77]. Despite
being a visible nding on ultrasound, the exact
implications of a niche on future pregnancies are
unknown.
4.9 Pelvic Floor Following
Cesarean Delivery
Both pregnancy and delivery are known to cause
alterations to the pelvic oor, some of which may
lead to pelvic oor dysfunction. Vaginal delivery
may cause nerve, muscle, and connective tissue
damage, but the effects of planned cesarean
delivery remain unclear. Using 3D sonography,
studies have demonstrated that pelvic oor muscles undergo distension during crowning, and
this distension has been implicated in levator ani
avulsion. This distension and the force that the
fetal head exerts during pushing may also lead to
nerve compression and subsequent muscle atrophy. In a review of six publications on 3D sonography of levator ani muscles both antepartum and
postpartum, Carvalho de Araujo found that across
all studies, vaginal deliveries were associated
with a larger genital hiatus size compared to
cesarean deliveries. These studies also found no
major levator ani injury in women who underwent cesarean delivery, including those who
underwent second-stage cesarean. Furthermore,
a smaller hiatal area antepartum was associated
with a higher risk of levator injury during delivery; however, no threshold for prediction of
injury could be established [80]. In a similar
study by Falkert, 3D ultrasonography was performed 2days postpartum to evaluate the levator
ani anatomy. Women who had undergone vaginal
delivery of any type, including operative delivery,
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