JSUR Journal

Introduction

There is no evidence regarding the optimal timing for non-surgical treatment of Adhesive Small Bowel Obstruction (ASBO), but the latest guidelines from Bologna (2017) indicate that a 72-hour period is safe and appropriate [1]. Continuing non-operative treatment for more than three days in cases with persistent high output from a decompression tube, but no other signs of clinical deterioration, however, remains subject to debate. However, there is evidence that surgical intervention after this period increases the odds of prolonged mechanical ventilation, infectious, thromboembolic, and acute cardiac complications [2]. Other guidelines recommend surgical consultation for any ASBO patient that does not improve after 24 - 48 hours of non-operative management [3]. According to Behman study, operative management of ASBO is associated with significantly reduced risk of recurrence [4]. Thus, it is evident that the selection of a specific time frame for surgical intervention in ASBO remains an unresolved and highly relevant issue. The objective of this study was to determine the relationship between surgical timing and clinical outcomes in patients with ASBO. We hypothesized that patients undergoing earlier surgical intervention would experience better clinical outcomes.

Method

This study was approved by the Helsinki Committee of Soroka University Medical Center (approval number: 0131-21-SOR). This is a retrospective cohort study of patients who underwent surgery for adhesive bowel obstruction at Soroka University Medical Center, Israel, from 2000 to 2021 (Figure 1). The patients were divided into three groups based on the timing of surgery: within 12 hours of admission (Group 1), between 12 and 24 hours (Group 2), and more than 24 hours after admission (Group 3). Inclusion criteria for the study were non-elective patients over 18 years of age, admitted with a primary diagnosis of small bowel obstruction (SBO), identified by the ICD-10 code. Exclusion criteria included patients with bowel obstruction caused by strangulated hernia, neoplastic processes, internal hernia, inflammatory process and infections (Crohn disease, tuberculosis etc.), intussusception, intraluminal obstruction due to a foreign body, as well as patients with signs of strangulated bowel obstruction (persistent severe pain, elevated blood lactate levels greater than 2 mmol/L). These criteria effectively excluded any other causes of bowel obstruction except adhesive small bowel obstruction. Patient data were obtained from electronic medical records at a single medical center. The dependent variables examined in the study were sex, age, length of hospital stay, postoperative complications, operation time, need for reoperation, emergency room readmission and mortality within 30 and 60 days. The postoperative complications analyzed included wound infections (surgical site infections, sepsis, pneumonia, urinary tract infections), cardiovascular events (pulmonary edema, arrhythmia, myocardial infarction, venous thromboembolism), acute kidney injury and wound dehiscence.

Statistical Analysis

Descriptive statistics were used to summarize the data through summary tables. For continuous variables, the median along with the first and third quartiles (Q1 and Q3) were presented, supplemented by means and standard deviations where applicable. Categorical variables were described using counts and percentages, rounded to one decimal place. Between-group comparisons were conducted using 95% confidence intervals and/or p-values, with percentages rounded to one decimal place. The Mann-Whitney test was employed for non-normally distributed continuous variables, while the chi-square test was utilized for categorical variables. Separate logistic regression models were constructed for each dependent variable, including second SBO surgery, complications after surgery, Deep Vein Thrombosis (DVT), and Urinary Tract Infection (UTI). The independent variables analysed included age at the time of surgery, gender, and the urgency of the SBO surgery (categorized as non-urgent if more than 12 hours). The results were reported as odds ratios (ORs) with 95% Confidence Intervals (CIs). All analyses were conducted using RStudio, version 1.1.423.

Figure 1: Cohort diagram of patient selection criteria. SBO = small bowel obstruction, ASBO = adhesive small bowel obstruction.

Results

According to the inclusion criteria, 2210 individuals were included in the study. Of these, 114 (5.2%) underwent surgical intervention within the first 12 hours of admission, 426 (19.2%) patients underwent surgery between 12 and 24 hours, and 1670 (75.6%) patients were operated on after 24 hours (Table 1). A total of 814 (36.8%) men and 1396 women (63.2%) were included in the study. There is a statistically significant difference in gender distribution across the three groups. Males comprised 33.3% of those operated within 12 hours, 43.7% in the 12-24-hour group and 35.3% in the >24 - hour group (p= 0.0046). Female made up a larger portion of patients, particularly in the >24-hour group (64.7%). The median age significantly increases with delay in surgery: 34.9 years for patients in the first group, 40.3 years in the second group and 50.3 years in the third group (p < 0.001). The need for reoperation is low in all groups, but it increases with surgical delay (0% within 12 hours, 5.6% for 12-24 hours, and 2.4% for>24 hours, p<0.001). Overall, 29.1% of patients experienced ER readmission with no statistically significant difference between groups (p=0.44). Mortality rates within 30 and 60 days are very low, with only one death reported in each timeframe across all groups, showing no significant difference (p=1.000). The median duration of surgery does not significantly vary across groups, ranging around 1.22 to 1.34 hours (p= 0.211). Hospital stay duration (Figure 2) increases notably with delayed surgery, with mean stay of 0.95 days for surgeries within 12 hours, 1.25 days for 12-24 hours, and 4.48 days for >24 hours (p<0.001). The percentage of patients undergoing laparoscopic surgery is higher thazln patients underwent open surgery, from 60.5% within 12 hours to 58.5% in the 12-24-hour group, and 64.6% in the >24-hour group (p=0.051). Complication rates increase with surgical delay (Figure 2). Patients operated within 12 hours had an 11.4% complication rate, compared to 24.6% in the 12-24-hour group and 20.1% in the >24-hour group (p=0.005). According to a multivariate analysis of parameters such as reoperation (Table 2), a statistically significant correlation with patient age was observed (OR 1.02; 95% CI 1.00-1.03; p=0.007).

For each additional year of age, the odds of reoperation increase by 2%, like the risk of postoperative complication increases by 1% (OR 1.01; 95%CI 1.00-1.01; p=0.005). Surgical interventions performed more than 12 hours after patient admissions were associated with more than twice complication rate than those operated on within the first 12 hours (OR 2.48; 95%CI 1.384.82; p=0.004). Surgeries performed more than 24 hours after admission have 82% higher odds of complications compared to surgeries done within the first 12 hours (OR 1.82; 95%CI 1.043.45; p=0.049). Laparoscopic surgery was associated with 31% lower odds of complications compared to open surgery (OR 0.69; 95%CI 0.56-0.86; p=0.001). Additionally, a statistically significant association was identified between postoperative complications and reoperation (OR 1.9; 95%CI 1.09-3.60; p=0.033). Patients who need reoperation have significantly higher odds of developing complications.

Table 1: Patient and hospital characteristics.

Figure 2: Distribution of Length of Hopsital Stay (LOS) and postoperative complication for Adhesive Small Bowel Obstruction (ASBO) in three surgical group of patients.

Table 2: Multivariate analysis of predictors for reoperation and complications parameters.

Table 3: Postoperative complications.

According to postoperative complications (Table 3), the risk of developing deep vein thrombosis (DVT) in the lower extremities was observed in 3 patients (2.6%) in the first group, 1 patient (0.2%) in the second group, and 15 patients (0.9%) in the third group (p=0.045). The other presented parameters did not demonstrate statistical significance. Based on multivariate analysis (Table 4), the risk of lower extremity thrombosis was dependent on the timing of the surgery, indicating that patients who undergo surgery after a 12-hour delay have a lower risk of DVT compared to those operated on <12 hours. (OR 0.27; CI 0.08-1.19; P=0.044). Urinary tract infection were identified in 4 (3.5%), 7 (1.6%) and 65 (3.9%) in the three groups respectively, with the highest rate observed in the >24 hour group (Table 3). This trend approached but did not reach statistical significance (p=0.075). But urinary tract infection was dependent on the patient’s age in multivariate analysis (OR 1.02; CI 1.00-1.03; P= 0.005). This result is statistically significant, suggesting that increasing age is associated with a slightly higher risk of developing UTI. Each additional year of age increases the odds of UTI by 2%. There is no statistical significance among postoperative complications such as sepsis (p=0.403), pneumonia (p=0.112), pulmonary edema (p=0.872), surgical site infection (p=0.109), dehiscence (p=0.637), arrhythmia (p=0.260) and myocardial infarction (p=0.197) between three groups of patients.

Table 4: Multivariate analysis of predictors for Deep Vein Thrombosis (DVT) and Urinary Tract Infection (UTI).

Discussion

Duration of the period in which non-operative management of ASBO can be tried is subject to debate. Evidence for the optimal duration of non-operative is absent, but consider a 72-h period consider as safe and appropriate [1], while others authors noted observation of adhesive SBO to be appropriate for no more than 5 days [5]. Th eEAST Practice Management Guidelines for Small Bowel Obstruction also suggest that non operative management can be attempted for up to 3 to 5 days [6]. Cox et al. demonstrated in their study involving 123 patients with SBO that 88% of the obstructions were resolved within 48 hours. They suggested that a majority of this patients can be managed conservatively within this time frame [7]. In our study, we hypothesized that earlier surgical intervention in patients with adhesive small bowel obstruction (ASBO), performed in the earlier time out of 72 hours of nonoperative management window, improves clinical outcomes and reduces postoperative complications. Accordng to our data, a significant proportion of surgical interventions were performed in female patients (63.2% vs 36.8%, p=0.005), that also observed by several other authors [2,5]. Our results indicate that the mean age of patients selected for the study was 46.8 years. It can also be noted that older patients (mean age 50.3 years) underwent surgery at later time points, after 24 hours (p <0.001). Our study demonstrated that older patients and females are more likely to experience delayed surgery. Table 1 shows that the need for reoperation is time dependent, with 0% of patients requiring reoperation when surgery performed within 12 hours of admission, compared to 5.6% and 2.4% patients who underwent surgery after 12 and 24 hours, respectively (p<0.001). This demonstrates a reduction in the need for reoperation in patients who underwent early surgical intervention. In the study by Texeira, conducted on 4,163 patients with ASBO, early surgical intervention within the first 24 hours and beyond this time frame did not show a significant association with the need for reoperations (p=0.264) [8]. But in a study of Bickell performed on 141 patients, it demonstrated that the risk of bowel resection significantly rises when surgery is delayed for more than 24 hours. The risk of resection was 4% among patients with 24 hours of unresponsive symptoms and it increased to 10% to 14% through 96 hours [9]. Our data demonstrate a 2-fold increase in postoperative complications in patients who underwent surgery after 24 hours (11.4% vs 20.1%, p=0.005). Delayed surgery more than 12 hours from admissions was significant predictor for postoperative complications in surgery in both delayed surgeries > 12-hours (OR 1.82; CI 1.04-3.45; p=0.049) and > 24-hours (OR 2.48; CI 1.38-4.82; p=0.004) in multivariate analysis. Prolonged surgery may lead to increased physiological stress, tissue trauma, and anesthesia-related complications. These are confirmed with the findings by Joseph et al. where a retrospective analysis of 91 patients undergoing laparotomy for ASBO in which a delay of more than 48 hours was associated with a 2-fold increase in the rate of postoperative complications [10]. Our data indicate a statistically significant association between postoperative complications and patient age (OR 1.01; CI 1.00-1.01; p=0.005).