Risk Assessment of Surgical Site Infections After Cesarean Delivery in Patients with Gestational Diabetes Cases

Introduction

Surgical site infections (SSIs) remain a significant postoperative complication following cesarean section, contributing to increased maternal morbidity, prolonged hospital stays, and elevated healthcare costs [1,2]. Patients with gestational diabetes mellitus (GDM) – a condition characterized by glucose intolerance first recognized during pregnancy – are particularly vulnerable to SSIs due to immune dysfunction, hyperglycemia-induced impairment of wound healing, and the increased likelihood of macrosomia and polyhydramnios that complicate surgical management [3,4].

Despite advances in perioperative care, the incidence of SSIs in patients with GDM remains concerning, with reported rates higher than in non-GDM populations [5]. While previous studies have identified potential risk factors such as obesity, poor glycemic control, and the frequency of vaginal examinations, the literature is fragmented and sometimes contradictory [6,7]. Many studies lack robust multivariate analyses or failed to simultaneously consider procedural variables – such as surgical duration and antibiotic prophylaxis – alongside patient-specific factors, limiting the generalizability of their conclusions. Furthermore, variations in diagnostic criteria and infection surveillance practices across studies contribute to inconsistencies in reported SSI rates.

This study aims to address these gaps by comprehensively analyzing both patient-related and procedure-specific risk factors for SSIs in GDM patients undergoing cesarean section. We seek to provide a clear understanding of the independent predictors of infection, with the goal of informing targeted preventive strategies to improve surgical outcomes in this high-risk population.

Material and Methods

STUDY DESIGN:

A comprehensive retrospective analysis was undertaken at our institution to elucidate the risk factors associated with surgical site infections subsequent to cesarean sections in individuals diagnosed with GDM. This inquiry spanned a period from January 2020 to December 2023. Within the 30-day postoperative window, incisional infections were diagnosed through a set of specific criteria, including observable signs of infection such as redness, pain, or swelling at the incision site, the successful cultivation of pathogens from the superficial incisional tissues or fluid samples, and the presence of pus or purulent discharge emanating from the wound. A total of 60 patients who experienced surgical site infections subsequent to their surgical procedures were categorized into the infection group for detailed evaluation. To facilitate a robust comparison, a control group was constituted, comprising 120 patients from the same timeframe who did not manifest surgical site infections, thus ensuring a level of comparability and control between these 2 distinct cohorts. Patient data were obtained through systematic screening of the hospital’s electronic medical records database. Informed consent was obtained from all subjects. The study was approved by the Ethics Committee of Xi’an People’s Hospital (Xi’an Fourth Hospital) (approval number: 2024-KY-132(K)) and conducted in accordance with relevant guidelines and the Declaration of Helsinki. All procedures adhered to ethical standards for medical research involving human subjects. Participant data were handled confidentially, with personal identifiers removed prior to analysis to ensure privacy.

INCLUSION AND EXCLUSION CRITERIA:

Inclusion criteria encompassed patients diagnosed with GDM according to the American Diabetes Association (ADA) guidelines, confirmed via oral glucose tolerance tests (OGTT) during pregnancy. Participants included must have undergone a cesarean section, either elective or emergency, within the study period from January 2020 to December 2023. Only those with comprehensive medical records, facilitating a thorough evaluation of their gestational and surgical history, were considered. All participants provided informed consent, demonstrating their understanding and voluntary participation in the study, after being fully briefed on its scope, methodologies, and potential implications.

We excluded individuals whose conditions might introduce confounding factors or biases into the study’s outcomes, such as patients with pre-existing chronic infectious diseases (eg, chronic hepatitis or HIV/AIDS) that might skew the assessment of surgical site infections. Those with multiple gestations, such as twins or triplets, were excluded due to the added complexity and risk factors these cases entail. Patients with a history of wound infections following previous cesarean sections were also excluded to prevent potential predisposition biases. Patients with missing or incomplete clinical records essential for the assessment of study variables were excluded to preserve data integrity and ensure the validity of statistical analyses. Lastly, individuals with systemic diseases that significantly impair immune function, such as systemic lupus erythematosus or chronic steroid use, were excluded, as these conditions might independently elevate the risk of surgical site infections.

DATA COLLECTION:

To elucidate factors influencing surgical outcomes, we meticulously collected extensive patient data [8,9]. The variables assessed were prophylactic antibiotics use, intraoperative blood loss, incision length, BMI, number of anal or vaginal examinations, amniotic fluid contamination, genital tract inflammation, and premature rupture of membranes.

Prophylactic antibiotics use was determined based on medication administration records, specifically whether antibiotics were administered within 30–60 minutes prior to skin incision. Intraoperative blood loss was estimated by the surgical team and recorded in operative notes, based on suction volume and sponge count. Incision length was documented by the surgeon in operative reports. BMI was calculated using height and weight recorded at hospital admission. The frequency of anal or vaginal examinations was extracted from labor and delivery nursing records. Amniotic fluid contamination was assessed intraoperatively by the attending obstetrician based on visual inspection, and classified according to standard clinical grading (eg, clear, meconium-stained grade I–III). Genital tract inflammation was diagnosed based on clinical findings such as purulent discharge, vulvovaginal erythema, and confirmed where applicable by laboratory testing (eg, leukocyte count in vaginal secretions). Premature rupture of membranes (PROM) was defined as spontaneous rupture of membranes prior to the onset of labor, confirmed through patient history, sterile speculum examination, and/or positive amniotic fluid tests (nitrazine, ferning, or Amnisure).

STATISTICAL ANALYSIS:

For variables adhering to normal distribution, the independent-sample t test was used to assess inter-group differences, with outcomes expressed as means±standard deviations. Categorical variables were depicted through frequencies and percentages, and the chi-square (χ²) test was used to examine their associations or independencies. Following the identification of significant determinants in univariate analyses, these variables underwent further scrutiny through multivariate logistic regression analysis, enabling the estimation of odds ratios and confidence intervals. To account for potential confounders, multivariate logistic regression was performed. Variables with a P value <0.1 in univariate analysis or considered clinically relevant (eg, BMI, prophylactic antibiotic use, genital tract inflammation, amniotic fluid contamination, premature rupture of membranes, and frequency of vaginal examinations) were included in the model. This approach facilitated adjustment for confounding and identification of independent predictors of surgical site infection. A stepwise selection method was applied to enhance model parsimony and fit. Statistical hypotheses were evaluated bidirectionally, adopting a significance level of P<0.05 to determine statistical relevance. All statistical analyses were performed using IBM SPSS Statistics for Windows, Version 27.0 (IBM Corp., Armonk, NY, USA).

Results

PATIENT DEMOGRAPHICS:

In the postoperative wound infection group, there were 60 patients, with a mean age of 33.56±4.86 years and a mean BMI of 25.21±1.86 kg/m2. The non-infection (control) group comprised 120 patients, with a mean age of 33.69±5.86 years and a mean BMI of 25.15±1.98 kg/m2. The fasting blood glucose levels were 6.9±1.5 mmol/L in the infection group and 6.6±1.3 mmol/L in the non-infection group. The mean surgery duration was 68±10.5 minutes for the infection group and 65±9.8 minutes for the non-infection group. Statistical analysis revealed no significant differences between the 2 groups in terms of age, BMI, fasting blood glucose, or surgery duration (all P>0.05) (Table 1).

UNIVARIATE ANALYSIS OUTCOMES OF POST-CESAREAN INFECTION RISK FACTORS:

Univariate analysis identified several variables with statistically significant differences between the infection and non-infection groups. Prophylactic antibiotic use was observed in 43.3% of the infection group and 83.3% of the non-infection group (χ2=28.601, P<0.001). BMI ≥25 kg/m2 was present in 65.0% of the infection group and 47.5% of the non-infection group (χ2=4.244, P=0.039). Anal or vaginal examinations ≥3 times were documented in 73.3% of the infection group and 35.0% of the non-infection group (χ2=22.046, P<0.001). Amniotic fluid contamination was noted in 65.0% of the infection group versus 17.5% of the non-infection group (χ2=38.503, P<0.001). Genital tract inflammation was present in 70.0% of the infection group and 20.0% of the non-infection group (χ2= 40.936, P<0.001). Premature rupture of membranes occurred in 70.0% of the infection group and 17.5% of the non-infection group (χ2=46.181, P<0.001). No significant differences were observed for intraoperative blood loss ≥300 mL (χ2=0.0029, P=0.957) or incision length ≥10 cm (χ2=0.0034, P=0.954) between the 2 groups. Detailed results are presented in Table 2.

MULTIVARIATE LOGISTIC REGRESSION ANALYSIS OF POST-CESAREAN INFECTION RISK:

Multivariate logistic regression analysis was conducted to identify independent risk factors for SSIs among cesarean section patients with GDM. The following variables were entered into the model: BMI ≥25 kg/m², prophylactic antibiotic use, frequency of anal or vaginal examinations (≥3 times), amniotic fluid contamination, genital tract inflammation, and premature rupture of membranes.

The analysis revealed that prophylactic use of antibiotics was independently associated with a reduced risk of SSI (OR=0.449, 95% CI: 0.212–0.952, P=0.037), indicating a protective effect. In contrast, the frequency of anal or vaginal examinations ≥3 times (OR=2.213, 95% CI: 1.020–4.803, P=0.045), amniotic fluid contamination (OR=3.060, 95% CI: 1.071–8.745, P=0.037), premature rupture of membranes (OR=2.555, 95% CI: 1.038–6.289, P=0.041), and genital tract inflammation (OR=3.153, 95% CI: 1.239–8.025, P=0.016) were all independently associated with an increased risk of SSI (Table 3).

POST HOC POWER ANALYSIS:

To evaluate the adequacy of the sample size in detecting meaningful associations, a post hoc power analysis was performed for all 12 independent variables assessed in the univariate analyses. This included 8 binary variables (prophylactic antibiotic use, BMI ≥25 kg/m², ≥3 anal/vaginal examinations, amniotic fluid contamination, genital tract inflammation, premature rupture of membranes, intraoperative blood loss ≥300 mL, and incision length ≥10 cm) and 4 continuous variables (age, BMI (continuous), fasting blood glucose, and operative time). Cohen’s h was used to quantify the standardized effect sizes for binary variables, while Cohen’s d was applied for continuous variables. Individual post hoc power calculations were weighted by the absolute value of their respective effect sizes to reflect their contribution to overall detection ability. When all variables were combined, the overall weighted power was approximately 90%, suggesting that the sample size was adequate to detect most clinically relevant associations in this study.

Discussion

Cesarean section, while essential in managing obstetric complications, poses a heightened risk of SSIs, particularly in patients with GDM, whose impaired glucose metabolism compromises immune function and wound healing. Despite the clinical relevance, risk factors for SSIs in this vulnerable population remain under-characterized. This study aims to fill this gap by systematically evaluating both host-related and procedure-specific determinants of SSIs in GDM patients undergoing cesarean delivery [10,11]. By identifying independent predictors of infection, we seek to inform evidence-based strategies for targeted perioperative management and infection prevention. This study offers novel insights by specifically investigating SSI risk factors in cesarean section patients with GDM – a population under-represented in the literature. While prior research has explored general SSI predictors in obstetrics, few studies have conducted a focused multivariate analysis within the GDM subgroup, which is uniquely predisposed to infection due to immune dysfunction and altered wound healing dynamics associated with hyperglycemia [12,13]. The clinical significance of these findings lies in their potential to inform targeted perioperative strategies. By identifying modifiable risk factors such as the frequency of vaginal examinations and the timing of antibiotic prophylaxis, this study provides actionable guidance for reducing SSI incidence. Moreover, the data support enhanced intrapartum infection control protocols and risk stratification in GDM patients, contributing to improved maternal outcomes, reduced postoperative morbidity, and more efficient allocation of healthcare resources.

Univariate analysis revealed significant associations between SSIs and multiple clinical factors in cesarean section patients with GDM. Patients with ≥3 anal or vaginal examinations, amniotic fluid contamination, genital tract inflammation, and premature rupture of membranes had higher infection rates. Conversely, prophylactic antibiotic use was significantly more common in the non-infection group, indicating a potential protective effect. Elevated BMI (≥25 kg/m2) showed a moderate association with infection risk, whereas intraoperative blood loss ≥300 mL and incision length ≥10 cm were not significantly associated with SSIs. Multivariate logistic regression further identified independent predictors of infection. Prophylactic antibiotic use remained significantly protective (OR=0.449, P=0.037), while frequent vaginal examinations (OR=2.213, P=0.045), amniotic fluid contamination (OR=3.060, P=0.037), genital tract inflammation (OR=3.153, P=0.016), and premature rupture of membranes (OR=2.555, P=0.041) were independently associated with increased SSI risk. These results highlight the importance of targeted intrapartum infection control strategies and underscore the role of early antibiotic prophylaxis in reducing postoperative complications in GDM patients undergoing cesarean delivery.

The findings from the current study provide critical insights into the risk factors associated with surgical site infections following cesarean section in patients with GDM. The use of prophylactic antibiotics emerged as a significant protective factor, aligning with previous research that underscores antibiotic prophylaxis as an effective strategy in reducing the risk of surgical site infections across various types of surgeries [14,15]. The reduction of microbial load before surgery may explain the observed decrease in surgical site infections, thus emphasizing the importance of antimicrobial stewardship in obstetric surgical care. Conversely, factors such as multiple anal or vaginal examinations, amniotic fluid contamination, genital tract inflammation, and premature rupture of membranes were identified as increasing the risk of infection [16,17]. The association between frequent examinations and higher infection rates may be attributed to the increased opportunity for introducing pathogens to the genital tract and potentially disrupting the integrity of the natural barrier against infection.

The association between amniotic fluid contamination and SSIs may result from direct bacterial inoculation at the operative site, a risk potentially amplified in patients with GDM due to impaired immune responses and hyperglycemic conditions that facilitate bacterial growth [18]. Genital tract inflammation and PROM similarly indicate compromised mucosal barriers, increasing susceptibility to ascending infections. Specifically, genital tract inflammation may involve pro-inflammatory mediators that impair wound healing, thereby predisposing surgical sites to infection [19]. PROM contributes to extended exposure to pathogens and prolonged labor, both recognized as critical periods for microbial ascension. Additionally, the moderate correlation between elevated BMI and SSI risk likely reflects complex interactions involving altered immune function and impaired wound healing associated with adiposity [20,21]. Patients with GDM are more prone to surgical site infections due to hyperglycemia-induced impairments in innate immunity, including reduced neutrophil function and oxidative burst activity. Elevated glucose also facilitates the formation of advanced glycation end products, promoting endothelial dysfunction and delayed wound healing. Additionally, microvascular impairment limits tissue perfusion and antibiotic delivery, while the glucose-rich environment supports bacterial proliferation. These synergistic mechanisms underscore the need for targeted infection prevention strategies in this high-risk population.

Our findings align with and extend previous research on SSIs following cesarean delivery. The protective effect of prophylactic antibiotics observed in our study (OR=0.449, P=0.037) corroborates prior evidence supporting antibiotic prophylaxis as a cornerstone of infection prevention in obstetric surgery. However, unlike the randomized trials by Connery et al and Tuuli et al, which focused on postoperative wound dressing strategies (eg, silver nylon dressings, negative-pressure therapy) and found no significant reduction in SSI rates [22,23], our study emphasizes preoperative and intrapartum clinical factors as stronger predictors of infection risk in GDM patients. This suggests that optimal outcomes may depend more on upstream infection control rather than postoperative interventions alone. Furthermore, consistent with the population-based analysis by Tuuli et al [24], we identified premature rupture of membranes (PROM) and GDM as independent risk factors for SSIs. However, our study adds granularity by isolating a GDM-specific cohort and identifying additional modifiable variables (eg, frequent vaginal examinations and genital tract inflammation) not previously highlighted as independent predictors. This contributes novel insights into the multifactorial nature of SSIs in this high-risk population and supports the implementation of preventive measures targeting both microbial exposure and host susceptibility.

This study has several limitations. Firstly, the retrospective design introduced potential biases, including selection bias, as the data were limited to patients treated at a single institution, which may affect the generalizability of the results. Secondly, certain clinically relevant variables, such as labor-related factors (eg, duration of labor, induction, and type of anesthesia), were not included due to incomplete documentation. Future prospective studies with standardized data collection protocols are necessary to incorporate these variables and explore their impact on SSI risk in patients with GDM undergoing cesarean delivery. Moreover, the single-center design may limit the external validity of the findings. To improve generalizability and reduce biases, multi-center prospective studies are warranted. Lastly, while the homogeneity of surgical techniques at a single institution provides consistency, it may not reflect the variability seen in broader surgical practices, which could have influenced the results. Future research should focus on investigating the underlying mechanisms of infection susceptibility in GDM patients, particularly the roles of hyperglycemia and immune dysfunction. Additionally, exploring novel preventive interventions, such as alternative antibiotic regimens, modified surgical protocols, or advanced wound care techniques, could help further reduce the risk of SSIs in this high-risk population.

Conclusions

Frequent anal or vaginal examinations, amniotic fluid contamination, premature rupture of membranes, and genital tract inflammation significantly elevate the risk of surgical site infections following cesarean section in patients with GDM. Conversely, the prophylactic use of antibiotics is a protective factor. Recognizing and addressing these factors through preventive measures is crucial for reducing the incidence of surgical site infections.

Availability of Data and Materials

The datasets used and/or analyzed during the present study are available from the corresponding author on reasonable request.