Abstract
Objectives: To determine the rates of surgical site infections
following continuous as compared to interrupted subcutaneous tissue
closure technique during cesarean delivery.
Design: Retrospective study.
Setting: Tertiary, university-affiliated medical center.
Population: Term pregnant women who underwent elective or
emergent cesarean delivery at our center during the years 2008-2018.
Methods: Group allocation was based on type of subcutaneous
tissue closure. The study group included women who underwent either
elective or emergent cesarean delivery with continuous subcutaneous
tissue closure, while the control group comprised those with interrupted
subcutaneous tissue closure. We excluded women with suspected infectious
morbidity prior to cesarean delivery.
Main outcome measures: Rate of surgical site infection (SSI)
comparing women who had undergone continuous as compared to interrupted
subcutanous suturing.
Results: Final analysis included 6,281 women. We performed
continuous subcutaneous tissue closure in 37.4% (1,867/4,988) of
scheduled cesarean deliveries, and 45.8% (592/1,293) of emergent
cesarean deliveries. The rate of SSI was significantly lower following
continuous as compared to interrupted subcutaneous tissue closure, in
both elective (2.7% vs. 4.5%, respectively, P=0.031) and emergent
cesarean delivery (3.2% vs. 5.4%, respectively, P=0.036), in
nulliparous and multiparous women. Similarly, secondary outcomes such as
re-admission rates within 6 weeks due to SSI, post-operative maternal
fever, and need for antibiotic treatment were significantly lower
following continuous subcutaneous closure technique.
Conclusions: Continuous subcutaneous closure technique during
cesarean delivery yields a lower rate of surgical site infections
compared to the interrupted technique.
Key words: Cesarean delivery (CD), subcutanous suturing,
surgical site infection (SSI).
Introduction
Cesarean delivery (CD) rates continues to rise worldwide
.1–3, accounting for more than 26% of births in the
United Kingdom in 2015 . Although considered safe, CD is still
associated with both short- and long-term maternal
morbidities.4
Postpartum surgical site complications such as hematomas, seromas,
surgical site infection (SSI), and wound breakdown develop in 1% - 2%
of both scheduled and emergency primary CDs.6–8 Risk
factors for wound complications include high body mass index (BMI) and
comorbidities.9 One of the preventive measures for
reducing the incidence of wound complications following CD is
approximation of the subcutaneous tissue.10 A 2004
Cochrane review addressed this surgical step and demonstrated a
significant one-third reduction in all surgical site complications
following suturing of the subcutaneous layer.11 A
later meta-analysis further supported a reduction in the odds of
developing any type of wound complication following this intervention,
particularly in women with obesity and subcutaneous tissue depth ≥ 2
cm.12
Despite the above evidence of subcutaneous tissue closure superiority,
the preferred surgical technique for subcutaneous tissue closure has not
been adequately studied. A single randomized controlled trial, comparing
continuous to interrupted suturing in women with a BMI > 30
kg/m2, showed lower rates of all wound complications
when using interrupted suturing.13 However, it appears
that results of this study were insufficient to make a clear decision
about subcutaneous tissue closure technique. In recent years, specific
guidelines addressing each of the pre, intra, and post-CD steps have
been developed in an attempt to improve patient
outcome.14-18 These guidelines, which include the
Enhanced Recovery After Surgery (ERAS) program, also did not provide a
clear statement about the preferred suturing technique for subcutaneous
approximation following CD.
Therefore, the current study aimed to report the rate of SSI when
comparing two surgical techniques, continuous versus interrupted, of
subcutaneous tissue closure during CD.
Materials and Methods
Study procedures
This was a retrospective study of women delivered by CD at our tertiary
care center, during 2008-2018. Our Obstetrics and Gynecology department
provides care to approximately 15,000 patients annually, including
nearly 5,500 births. The study was approved by our local Research
Ethics Board (0361-19-RMB). Informed consent was waived for acquisition
of de-identified patient data. Patient information was accessed through
the hospital’s computerized database, including patients’ demographics
and general medical and obstetric characteristics, in addition to both
intrapartum and postpartum maternal and neonatal variables. Furthermore,
known associated factors and morbidities relevant to surgical site
complications were also identified, such as BMI, total time duration of
the CD, diabetes of pregnancy, and number of prior CDs. The data were
used for multivariable regression analysis.
The study group was comprised of women with known pregnancy outcomes at
or beyond 37 weeks’ gestation who underwent either elective or emergent
CD with continuous subcutaneous tissue closure (c-STC), while the
control group was comprised of those with interrupted subcutaneous
tissue closure (i-STC). Gestational age was confirmed by first trimester
ultrasound. Exclusion criteria included patients who received any
antibiotic regimen other than the routine prophylactic cephalosporin (or
clindamycin in cases of drug allergy) before the CD or GBS prophylaxis.
We follow the risk factor-based approach and provide intrapartum
chemoprophylaxis to prevent early-onset GBS neonatal disease after ≥ 18
hours of prolonged rupture of membranes. Wide spectrum intravenous
antibiotics are also prescribed to women with suspected intrapartum
clinical chorioamnionitis, defined as isolated maternal fever with one
or more of the following: maternal tachycardia, fetal tachycardia,
leukocytosis, uterine tenderness, and malodorous amniotic fluid, or
patients with postpartum endometritis. In addition, we excluded women
who underwent CD due to multiple gestation, as these have been shown in
a previous studies to have increased rates of SSI.19
Our institutional general CD technique is in alignment with the ERAS
guideline15 and consists of the following steps:
- Regional anesthesia is the principal method of anesthesia.
- Prophylactic intravenous cephalosporin 2 g, or intravenous
clindamycin 900 mg in case of penicillin allergy, is given within 60
minutes of skin incision.
- The CD surgical site is prepared with chlorhexidine-alcohol scrub.
- The vagina is scrubbed with 4% chlorhexidine.
- A Pfannenstiel skin incision is performed.
- Exposure of the subcutaneous tissue layer, opening of the underlying
fascia, bluntly or sharply, is done while maintaining hemostasis, and
creating a bladder flap. This is followed by low uterine segment
transverse incision and delivery of the newborn.
- The choice between a single or double layer for hysterotomy site
closure is at the primary surgeons’ discretion.
- The peritoneum is not routinely approximated.
- We close the fascia layer with continuous sutures.
- Since we cannot measure reliably the subcutaneous tissue layer
thickness, it is our department routine to suture this layer with 2-0
Vicryl (Ethicon). The choice between c-STC or i-STC is at the primary
surgeon’s discretion. c-STC sutures were placed approximately 1 cm
from the edge of the incision and 1 cm apart, without excessive
tension.
- At the time of the study, the skin was closed with metal clips,
covered with sterilized dressing, and kept dry for approximately 24
hours.
- Unless complications arise, women are hospitalized for 96 hours,
during which evaluation and care of the surgical wound site is made.
- Metal clips are removed in community health care facilities, usually
within 5-7 days postoperatively.
The primary outcome of the study was the rate of postpartum SSI, defined
as localized abdominal/wound tenderness with or without maternal body
temperature > 38°C, and at least one of the following:
purulent drainage from the superficial incision, culture positive, or
incision opened by the surgeon. Secondary outcomes included the rate of
re-admission within 6 weeks postpartum due to SSI, rate and duration of
maternal fever and antibiotic use, CD-to-SSI time interval, rate of
bacteremia/sepsis, and post-op duration of hospitalization.
Statistical analysis
Descriptive variables were reported as means (±SD) for continuous
variables and numbers (percentages) for categorical variables. Study
variables were compared based on the student t-test, χ2 test, and ANOVA.
A multivariable regression model was used while controlling for
significant univariate factors found to be associated with a positive or
a negative outcome for surgical site infection including maternal age,
BMI, gestational diabetes and duration of CD. A 95% confidence interval
was considered statistically significant. SPSS for Windows, version 26
(SPSS, Inc., Chicago, IL), was used for data management and statistical
analysis. Separate sub-analyses were performed for both the elective and
emergent surgery groups.
Results
Maternal demographic characteristics, depicted in Table 1, were
comparable between the groups. Figure 1 presents a flow chart of
patients whose subcutaneous tissue layer was closed with either c-STC or
i-STC, and provides the primary outcome of the study. During the 10-year
study period, 12,896 pregnant women underwent CDs (incidence 23.4%),
of whom 6,281 women were eligible
for the final analysis. We performed c-STC in 37.4% (1,867/4,988) of
the scheduled CDs, and in 45.8% (592/1,293) of the emergent CDs. The
rate of SSI was significantly lower following c-STC compared with i-STC,
in both elective (2.7% vs. 4.5%, P<0.0001) and emergent
(3.2% vs. 5.4%, P=0.031) CDs.
Secondary outcomes are presented separately for elective and emergent
CDs in Tables 2 and 3, respectively. Among the scheduled CDs, we
observed that rates of readmission (0.9% vs. 1.7%, P=0.0025),
post-operative maternal fever (3.2% vs. 5.3%, p=0.021), and need for
antibiotic treatment (2.7% vs. 4.3%, P=0.038) were significantly lower
in the c-STC group as compared to the i-STC group. Similar findings were
observed for emergent CDs. No differences were found in the mean
duration of maternal fever, mean duration of antibiotic treatment,
CD-to-SSI latency interval, rates of bacteremia and/or sepsis, or
duration of hospitalization.
In a separate parity-based sub-analysis, significant findings were in
favor of the c-STC group as well. The rate of SSI in nulliparous women
was significantly reduced following c-STC as compared to i-STC in
elective (2.4% vs. 4.2%, P=0.029) and emergent (3.1% vs. 5.6%,
P=0.033) CDs. A lower rate of SSI was also noted among multiparous women
after c-STC as compared to i-STC, in both elective (2.8% vs.
4%,P=0.045) and emergent (3.7% vs. 6.5%, P=0.034) CDs. Re-admission
rates due to SSI were also significantly lower in nulliparous and
multiparous women following c-STC as compared to i-STC both in
elective (0.9% vs. 1.7%, P=0.0025) and emergent (1.5% vs. 3.1%,
P<0.0001) CDs.
Discussion