In 2016, approximately 1.3 million cesarean deliveries were performed in the United States.1 The most common complication after cesarean delivery is surgical site infection, occurring in 2–15% of women and representing a major cause of maternal morbidity and mortality.2–10 Surgical site infections result in prolonged hospital stays and increased financial burden to the health care system.3 In one study, attributable costs of wound infection and endometritis per affected woman were $3,700 and $4,000, respectively (in 2008 U.S. dollars).11 Evidence for a bundled approach using perioperative strategies and surgical techniques for cesarean delivery has not been adequately developed as previous studies were limited by small sample size, a meta-analysis of a variety of surgical bundles, or secondary analysis of a clinical trial for a different purpose.12,13 Further, newer evidence has made methods and results of previous studies obsolete.4,14
The Accreditation Council for Graduate Medical Education implemented a requirement within all graduate medical education curricula for residents to perform patient safety and quality improvement projects.15 Encouraged by this requirement, a resident-driven quality initiative using an evidence-based surgical bundle for cesarean delivery was implemented in December 2016 at MedStar Washington Hospital Center.10 We hypothesized that this quality improvement initiative would reduce the rate of cesarean surgical site infections. We sought to examine the rate of surgical site infections before and after the implementation of the quality initiative.
This was a quasi-experimental, preintervention and postintervention study of all women at 23 weeks of gestation or greater who underwent cesarean delivery at MedStar Washington Hospital Center between January 2015 and June 2018. All cesarean deliveries were covered by residents. MedStar Institutional Review Board approved this analysis. Women who underwent an emergency cesarean delivery, defined as such a rapid cesarean delivery that skin preparation was not completed owing to time constraints from the emergent nature of the surgery, or developed chorioamnionitis, defined as fever at least 38.0°C plus fetal tachycardia (greater than160 beats per min) or purulent fluid from the cervical os,16 were excluded.
The idea of an evidence-based surgical bundle was initially presented by a chief resident (T.K.) at a morbidity and mortality conference, followed by a literature review and publication of the epidemiology, prevention, and treatment for cesarean surgical site infections.10 A multidisciplinary team of attending obstetrician-gynecologists, maternal–fetal medicine specialists, anesthesiologists, and labor and delivery nurses reviewed the surgical bundle and assessed the feasibility of this quality initiative. Interventions that were common but were not standardized before the surgical bundle included use of clippers instead of a razor for hair removal,17 suture closure of subcutaneous tissue if wound thickness exceeded 2 cm,18 and dressing removal between 24 and 48 hours.19 Preoperative cefazolin, typically a 2-g intravenous dose, was administered before skin incision,20 though a 3-g dose was considered for women with body mass index (BMI, calculated as weight in kilograms divided by height in meters squared) at or above 40.
Components of our surgical bundle were developed based on published literature (Box 1). We chose to expand the use of preoperative azithromycin to all patients undergoing cesarean delivery. This decision was based on the randomized controlled study by Tita et al21 that demonstrated the effectiveness of adding azithromycin in women undergoing nonelective cesarean delivery4 and the lower rate of endometritis reported in their 2008 study of women having elective cesarean delivery. We implemented postpartum 2% chlorhexidine gluconate showers because this intervention has been included in previous perioperative bundles22–24 and it could easily be established into routine postpartum care though strong evidence is lacking. Postpartum nurses reviewed proper wound care before discharge.
Throughout the study period, residents organized formal and informal education to the operating staff regarding details of the bundle. Compliance was tracked for six bundle elements (intravenous cefazolin, intravenous azithromycin, chlorhexidine alcohol skin preparation, vaginal cleansing, placental removal, and suture skin closure) was reviewed monthly, and written feedback was given to the labor and delivery team. Compliance with the other elements (use of clippers instead of a razor, suture closure of subcutaneous tissue, dressing removal between 24 and 48 hours, and chlorhexidine shower) was not consistently documented in the chart. Therefore, these elements were not tracked.
The preimplementation period spanned January 1, 2015, through August 30, 2016. Bundle planning, adaptation, and implementation occurred between September 1, 2016, and November 30, 2016. The postimplementation period was from December 1, 2016, to June 30, 2018. The electronic medical record was used to identify all women who underwent cesarean delivery. Chart review was conducted to obtain outpatient, inpatient, and anesthesia data. We abstracted data on a broad variety of maternal demographic and clinical factors. Our primary outcome was predefined as surgical site infections (superficial incisional, deep incisional, and organ or space surgical site infections) using Centers for Disease Control and Prevention definitions occurring up to 6 weeks after cesarean delivery.19 Superficial incisional surgical site infection was defined as an infection of the skin or subcutaneous tissue with at least one of the following: purulent wound discharge, pathogenic organisms isolated from the incision, or erythema, induration, or tenderness. Deep wound infection was defined as an infection of deep soft tissues with at least one of the following: purulent wound discharge, spontaneous dehiscence, or evidence of deep tissue abscesses. Organ or space surgical site infection was defined as infection involving organs or space other than the incision, which was opened or manipulated during an operation and the presence of at least one of the following: purulent drainage, organisms isolated from organ or space, and evidence of abscess involving the organ or space.
We performed Cochran-Armitage Trend test to calculate the trend of quarterly compliance rates of the tracked bundle elements in the postimplementation period. Outcomes were compared between the preimplementation and postimplementation periods. The closure of obstetric units at two local hospitals during the postimplementation period may have resulted in a change of our patient demographics, because many women previously delivering at those hospitals delivered at MedStar Washington Hospital Center. To account for the potential demographic change, we performed Coarsened Exact Matching with k-to-k solution based on predefined factors including age, race–ethnicity, BMI, rupture of membranes, and labor.25 These factors were chosen because these were known risk factors for surgical site infections.10,26 The Coarsened Exact Matching coarsens each variable into substantively meaningful groups, exact match on these coarsened data, and then only retain the original uncoarsened values in the matched data. We used Coarsened Exact Matching over other techniques such as Mahalanobis distance or the propensity score because other methods require multiple iterations and re-matching.25 We used the χ2 test to analyze categorical variables and Student t-test for continuous variables. Odds ratios (ORs) with 95% CIs were also calculated. All statistical analyses were performed using Stata/IC 15.1.
A total of 3,942 women underwent cesarean delivery between January 2015 and June 2018: 312 were excluded owing to delivery during the implementation period (September–November 2016) and 483 because the cesarean was performed emergently or in the setting of chorioamnionitis. Using Coarsened Exact Matching, 1,100 women in the postimplementation period were matched to 1,100 women in the preimplementation period (Fig. 1).
In the postimplementation period, compliance with the six tracked components was more than 70% (Table 1). As expected, use of all six tracked components was higher in the postimplementation period compared to the preimplementation period (P<.01). Compliance with intravenous azithromycin, chlorhexidine alcohol skin preparation, vaginal preparation, and placenta delivery by cord traction improved during the postimplementation period (P for trend <.01, Fig. 2).
In the unmatched cohort, women who underwent cesarean delivery in the postimplementation period were more likely to be older and were less likely to be non-Hispanic black compared to those in the preimplementation period (P<.01). In the matched cohort, demographics were similar (Table 2).
In the unmatched cohort, women who underwent cesarean delivery in the postimplementation period compared to those in the preimplementation period were less likely to have surgical site infections (2.2% [33/1,523] vs 4.5% [73/1,624]; OR 0.47 [95% CI 0.31–0.71]; P<.001), superficial surgical site infections (1.0% [15/1,523] vs 2.4% [39/1,624]; OR 0.40 [0.22–0.74]; P<.01), and organ or space surgical site infections (1.3% [20/1,523] vs 2.5% [41/1,624]; OR 0.51 [0.30–0.88]; P=.01). This decrease in the rate of surgical site infections remained statistically significant after matching (1.9% [21/1,100] vs 4.1% [45/1,100]; OR 0.46 [0.27–0.77]; P<.001, Table 3).
In this cohort of women undergoing cesarean delivery, we found that a resident-driven quality initiative using a well-defined surgical bundle was associated with a statistically significant decrease in the rate of surgical site infections. This decrease in surgical site infections remained statistically significant even after Coarsened Exact Matching.
Previous studies have shown surgical bundles are associated with a reduction in surgical site infections after cesarean delivery.12,13 However, those studies are outdated owing to the emerging new evidence such as vaginal cleansing and preoperative intravenous azithromycin.4,5,14 A secondary analysis of a randomized controlled trial found that women who had four evidence-based interventions (preoperative cefazolin before skin incision, chlorhexidine-alcohol skin antisepsis, closure of subcutaneous layer, and suture subcuticular skin closure) compared to those who did not have all four interventions had 67% lower odds of surgical site infections.12 However, the randomized controlled trial was conducted for a different purpose. In the meta-analysis of six abstracts and eight published cohort studies, surgical bundles for cesarean delivery containing at least three of the evidence-based interventions such as chlorhexidine skin preparation, routine preoperative cefazolin, hair clipping, and placental removal with gentle traction were associated with decreased risk of surgical site infection by 67%.13 However, this study was limited by the inclusion of varying types of surgical bundles.
The Accreditation Council for Graduate Medical Education requirement for residents to participate in quality-improvement projects encouraged our residents to champion this quality initiative.15 There were a number of challenges during the implementation period, especially a resistance to altering workflow in the operating room and for postpartum care. However, the residents continued to educate the operating room staff with the support of the attending physicians. Continued reminders of the purpose behind the quality initiative and monthly compliance reports were helpful to encourage compliance with the new workflow.
Strengths of the study include the demonstration of a successful resident-driven quality initiative, which can serve to encourage residents in other residency programs and other disciplines. We demonstrated that our evidence-based bundle approach was associated with standardization of our clinical practice and reduced surgical site infections by 50%. We believe the quality of our data is high: Data were obtained from a chart review of outpatient, inpatient, and anesthesia records, and we used strict criteria for defining surgical site infections by using objective clinical data. Therefore, we are confident that rates of surgical site infections are accurate. In addition, Coarsened Exact Matching was used to account for potential demographic change owing to the closure of two local hospitals.
Our study is not without limitations. We may have underestimated the number of surgical site infections because some women may have gone to institutions outside the MedStar network for the care of surgical site infections. Information regarding a loss of follow-up was not available in our data. However, this condition would apply to all time frames of the study. Owing to the study design, it was not possible to identify which interventions (if any), alone or in combination, contributed to the reduction of surgical site infections. Because our study was not a randomized controlled trial, we can only infer correlation but not causation. It is possible that only the addition of preoperative azithromycin or vaginal cleansing is responsible for the reduced rate of surgical site infections. No adverse short-term neonatal outcomes have been reported with the use of preoperative maternal azithromycin administration.4 However, little is known regarding the long-term outcome. Emerging evidence has shown that intrapartum antibiotics may be associated with an infant gut microbiota imbalance, and this area warrants further investigation.27 Approximately 30% of women in the postimplementation period did not have vaginal cleansing or placenta removal by cord traction. In cases of urgent cesarean delivery, attending physicians may have opted out of vaginal cleansing or decide to perform manual removal of placenta, which may explain lower rates of vaginal cleansing or placenta removal by cord traction. We observed improving compliance on vaginal cleansing and placenta removal by cord traction during the postimplementation period.
In summary, our resident-driven quality initiative was associated with a statistically significant reduction in cesarean delivery surgical site infections. We also succeeded in standardizing our clinical practice and introducing new evidence-based interventions. Our resident-driven quality initiative may provide a template for other residents and residency programs in their development of quality improvement initiatives.
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