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: ‎
  1. Regional anesthesia is the principal method of anesthesia.
  2. Prophylactic intravenous cephalosporin 2 g, or intravenous‎ clindamycin 900 mg in case of penicillin allergy, is given within 60 minutes of skin incision.
  3. The CD surgical site is prepared with chlorhexidine-alcohol scrub.
  4. The vagina is scrubbed with 4% chlorhexidine‎.
  5. A Pfannenstiel skin incision is performed.
  6. 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.
  7. The choice between a single or double layer for ‎hysterotomy site closure ‎is at the primary surgeons’ discretion.
  8. The peritoneum is not routinely approximated.
  9. We close the fascia layer with continuous sutures.
  10. 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.
  11. At the time of the study, the skin was closed with metal clips, covered with sterilized dressing,‎ and kept dry for approximately 24 hours. ‎
  12. Unless complications arise, women are hospitalized for 96 hours, during which evaluation ‎and care of the surgical wound site is made‎.
  13. 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