European Journal of Cardiovascular Medicine

Intestinal anastomosis is a fundamental surgical procedure performed to restore continuity between two segments of the intestine following the removal of a pathological condition. It is commonly indicated for various gastrointestinal (GI) disorders, including inflammation, ischemia, trauma, obstruction, and malignancy [1,2]. Despite advances in surgical techniques, anastomotic leakage (AL) remains a major postoperative complication, contributing to significant morbidity, mortality, prolonged hospitalization, and increased healthcare costs [3].

The reported incidence of AL varies widely from 0.5% to 30%, depending on patient-related, surgical, and perioperative factors [4]. AL can lead to severe complications, including peritonitis, sepsis, and the need for additional invasive procedures, such as reoperation or percutaneous drainage [5]. Given the complexity of intestinal wound healing, multiple factors influence the integrity of an anastomosis. These factors can be broadly classified into:

1. Patient-related factors: Age, sex, body mass index (BMI), diabetes, hypertension, cancer, anaemia, neutropenia, malnutrition, and sepsis.
2. Preoperative factors: Prior abdominal surgery, chemotherapy, radiotherapy, steroid use, and anticoagulation.
3. Surgical factors: Duration of surgery, intraoperative blood loss, type of anastomosis, contamination level, urgency of the procedure, bowel perfusion, and anastomotic tension [6].

Studies have shown that certain modifiable risk factors, such as hypoalbuminemia, anaemia, intraoperative hypotension, prolonged surgery, and postoperative blood transfusions, significantly increase the likelihood of AL [7]. Smoking and alcohol consumption have also been implicated in delayed wound healing and impaired anastomotic integrity [8].

This study aims to identify and analyze the influence of different risk factors on the development of complications following elective small bowel anastomosis. By evaluating both preoperative and intraoperative parameters, we seek to improve risk stratification and optimize perioperative management strategies to minimize AL and its associated complications.

Aims and Objectives

Aim

This study aims to evaluate the risk factors contributing to anastomotic leakage (AL) following elective small bowel resection and anastomosis by analyzing patient demographics, perioperative variables, and surgical techniques.

Objectives

1. To assess the demographic profile of patients who develop anastomotic leakage postoperatively.
2. To determine the association between the following risk factors and anastomotic leakage:
• Preoperative factors:
• Hypoalbuminemia
• Anaemia
• Intraoperative factors:
• Surgeon’s experience
• Intraoperative hypotension
• Surgical technique used for anastomosis
• Duration of surgery
• Postoperative factors:
• Postoperative blood transfusions
• Dyselectrolytemia

By identifying these risk factors, the study aims to improve perioperative management strategies to reduce the incidence of anastomotic leakage and improve postoperative outcomes.

Study Design and Setting

This study was a prospective observational study conducted in the Department of General Surgery at Burdwan Medical College and Hospital over 18 months (April 2021 to September 2022)​.

Study Population

The study included patients undergoing elective small bowel anastomosis in the Department of General Surgery, BMCH, who met the inclusion and exclusion criteria during the study period​.

Inclusion Criteria

• Patients admitted to the surgical wards of Burdwan Medical College and Hospital.
• Patients undergoing elective primary intestinal resection and anastomosis during the study period.
• Patients willing to participate in the study and providing informed consent​.

Exclusion Criteria

• Paediatric patients (aged below 18 years).
• Patients with HIV/AIDS infection.
• Patients with carcinoma detected perioperatively.
• Uncontrolled diabetes mellitus.
• Active tuberculosis.
• History of prolonged steroid use.
• History of previous pelvic irradiation​.

Sample Size

A total of 50 patients were enrolled in the study. Based on hospital records from previous years, 65 patients underwent small bowel anastomosis at BMCH over 18 months. After excluding 15% of patients who did not meet the criteria and 10% who declined consent, the final sample size was determined to be 50​.

Study Timeline

• Recruitment of patients: April 2021 – February 2022 (10 months)
• Follow-up of recruited patients: March 2022 – May 2022 (2 months)
• Data analysis: May 2022 – July 2022 (2 months)​

Data Collection and Parameters Studied

Data were collected through case record forms (CRFs) and included:

1. Patient Demographics and Clinical History

• Age, sex, BMI, comorbidities (diabetes, hypertension, renal disease).
• Nutritional status (haemoglobin levels, serum albumin).
• History of smoking, alcohol consumption, steroid use, chemotherapy, radiotherapy​.

2. Preoperative Risk Factors

• Indication for surgery.
• Previous abdominal surgery.
• Baseline blood investigations (haemoglobin, urea, creatinine, albumin).

3. Intraoperative Risk Factors

• Type of anastomosis (hand-sewn vs. stapled, end-to-end vs. side-to-side).
• Bowel preparation, vascularity at the anastomotic site.
• Operative duration, intraoperative blood loss, need for transfusion.
• Use of abdominal drainage.

4. Postoperative Outcomes

• Incidence of anastomotic leakage (AL).
• Need for reoperation or percutaneous drainage.
• Other complications: wound infection, ileus, intra-abdominal abscess, pulmonary complications.
• Length of hospital stay, mortality within 30 days​.

Outcome Measures

The primary outcome was the incidence of anastomotic leakage (AL) and its association with risk factors.
The secondary outcomes included:

• Overall complication rate.
• Requirement for surgical intervention.
• 30-day postoperative mortality​.

Statistical Analysis

• Descriptive statistics (mean ± standard deviation for continuous variables, percentages for categorical data).
• Chi-square tests for categorical data and t-tests/Mann-Whitney U tests for continuous variables.
• Multivariate logistic regression analysis to identify independent predictors of anastomotic leakage.
• A p-value <0.05 was considered statistically significant.
• Analysis was performed using Epi-info version 6.0.1 and SPSS 20.0 for Windows​.

Ethical Considerations

The study was approved by the Institutional Ethics Committee (Approval ID: [XXXX]), and all patients provided written informed consent before participation​.

Incidence of Anastomotic Leakage

Among the 50 patients who underwent elective small bowel anastomosis, 6 patients (12%) developed anastomotic leakage (AL), while 44 patients (88%) had no postoperative leakage.

The overall incidence of AL in this study was comparable to reported rates in previous literature, which typically range between 5–20% depending on patient population and surgical technique. Early identification of high-risk patients remains essential for improving outcomes and reducing postoperative morbidity.

Table:1.Incidenceofanastomoticleak(n=50)

Figure:1.Incidenceofanastomoticleak(n=50)

Figure 1. Incidence of Anastomotic Leakage

This bar chart visually represents the proportion of patients with and without anastomotic leakage. The majority of cases (88%) had no leakage, while 12% developed postoperative anastomotic complications.

Sex Distribution and Anastomotic Leakage

The male-to-female ratio in the study population was 4.5:1, with 41 males (82.0%) and 9 females (18.0%). Among the 6 cases of AL, 5 were male (83.3%) and 1 was female (16.7%).

However, the association between sex and AL was not statistically significant (p = 0.927, Chi-square test), suggesting that sex alone was not a determining factor for AL in this cohort.

Table 3. Sex Distribution and Anastomotic Leakage

Statistical inference: Chi-square = 0.0082, p = 0.927 (not significant).

Figure: 3. Sexdistribution

Figure 3. Sex Distribution of Anastomotic Leakage Cases

This grouped bar chart compares the incidence of anastomotic leakage between males and females. While males were more common in the study population, sex was not a significant risk factor for AL (p = 0.927).

Summary of Demographic Risk Factors

The analysis of demographic variables did not identify age or sex as independent risk factors for anastomotic leakage (AL). Although AL was most commonly observed in the 41–50 years age group (66.6%), the association was not statistically significant (p = 0.613). Similarly, while 83.3% of AL cases were male, this was proportional to the overall male predominance (82%) in the study population, and the association with AL was not significant (p = 0.927).

Table 4. Summary of Demographic Risk Factors and Anastomotic Leakage

• Age and sex were not significant independent risk factors for AL in this study.
• AL was most common in the 41–50 years age group, but the association was not statistically significant
• Males were more frequently affected, but this reflected the overall male predominance in the study population rather than being a specific risk factor for AL.

Preoperative Risk Factors for Anastomotic Leakage

(A) ASA Score and Anastomotic Leakage

The ASA (American Society of Anaesthesiologists) score is a well-established predictor of surgical risk. In this study, 83.3% of AL cases had an ASA score of III, while no AL cases were reported in ASA I patients. The association between ASA score and AL was highly significant (p = 0.0001, Chi-square test), indicating that patients with poor preoperative health status (ASA III) had a significantly higher risk of developing AL.

Table 5. ASA Score and Anastomotic Leakage(n=50)

Statistical inference: Chi-square = 18.0397, p = 0.0001 (highly significant).

Figure:4. ASA Score Distribution in Anastomotic Leakage Cases

Figure 4. ASA Score Distribution in Anastomotic Leakage Cases

This stacked bar chart illustrates the relationship between ASA scores and AL. The majority of AL cases occurred in ASA III patients, highlighting the importance of preoperative risk stratification (p = 0.0001, significant).

(B) Smoking and Anastomotic Leakage

Smoking has been identified as a potential risk factor for impaired tissue healing. In this study, all 6 AL cases (100%) were smokers, while 59.1% of non-AL patients also had a smoking history. The association between smoking and AL was statistically significant (p = 0.05, Chi-square test), reinforcing its role as a modifiable risk factor in surgical outcomes.

Table 6. Smoking and Anastomotic Leakage

Statistical inference: Chi-square = 3.8352, p = 0.05 (significant).

Figure 5. Smoking and Anastomotic Leakage

This bar chart illustrates the relationship between smoking and AL. All AL cases were smokers, making smoking a significant risk factor (p = 0.05).

Key Findings: Preoperative Risk Factors (n=50)

• Patients with ASA III (n=10) had a significantly higher risk of AL (p = 0.0001), reinforcing the role of preoperative risk stratification.
• Smoking was significantly associated with AL (p = 0.05, n=32 smokers), emphasizing the importance of preoperative smoking cessation.

Section 4: Biochemical and Laboratory Risk Factors

(A) Serum Albumin and Anastomotic Leakage

Serum albumin is a key indicator of nutritional status and wound healing capacity. Patients who developed AL had significantly lower mean albumin levels (3.28 ± 0.14 g/dL) compared to those without leakage (4.16 ± 0.47 g/dL). The difference was statistically significant (p = 0.034, t-test), suggesting that hypoalbuminemia increases the risk of AL.

Table 7. Serum Albumin Levels and Anastomotic Leakage

Figure 6: Serum Albumin Levels in AL vs. Non-AL Patients

This boxplot illustrates the significantly lower albumin levels in AL patients, reinforcing the role of nutritional status in anastomotic healing (p = 0.034).

(B) Haemoglobin and Anastomotic Leakage

Result Narrative

Postoperative haemoglobin (Hb) levels were significantly lower in patients with AL (9.26 ± 0.77 g/dL) compared to those without AL (10.73 ± 0.34 g/dL). This difference was highly significant (p < 0.0001, t-test), suggesting that perioperative anaemia is a strong predictor of anastomotic failure.

Table 8. Haemoglobin Levels and Anastomotic Leakage

Figure7: Postoperative Haemoglobin Levels in AL vs. Non-AL Patients

This boxplot highlights significantly lower haemoglobin levels in AL patients, indicating that perioperative anaemia may impair wound healing (p < 0.0001).

(C) BMI and Anastomotic Leakage

Patients with AL had a significantly higher mean BMI (27.03 ± 2.83) compared to those without AL (23.53 ± 1.36, p = 0.005, t-test). This suggests that obesity may contribute to anastomotic failure, possibly due to poor tissue perfusion or increased intra-abdominal pressure.

Table 9. BMI and Anastomotic Leakage

Figure 8. BMI Distribution in AL vs. Non-AL Patients

This boxplot demonstrates that patients with AL had significantly higher BMI, reinforcing the association between obesity and anastomotic failure (p = 0.005).

Key Findings: Biochemical and Laboratory Risk Factors

• Hypoalbuminemia (p = 0.034) was a significant risk factor for AL, emphasizing the role of preoperative nutritional optimization.
• Anaemia (p < 0.0001) was strongly associated with AL, suggesting that perioperative haemoglobin optimization is critical.
• Higher BMI (p = 0.005) was significantly linked to AL, indicating that obesity management could reduce anastomotic failure risk.

Intraoperative Risk Factors

(A) Mechanical Bowel Preparation (MBP) and Anastomotic Leakage

Mechanical bowel preparation (MBP) is thought to reduce infection and improve healing. In this study, 50% of AL cases (n=3) did not receive MBP, while 90.1% of patients without AL (n=40) had undergone MBP. The association was statistically significant (p = 0.006, Chi-square test), suggesting that MBP may have a protective role in preventing AL.

Table 10. Mechanical Bowel Preparation and Anastomotic Leakage (n=50)

Figure 9:  Mechanical Bowel Preparation and Anastomotic Leakage

This stacked bar chart illustrates the relationship between mechanical bowel preparation (MBP) and anastomotic leakage. Patients who did not receive MBP had a significantly higher incidence of anastomotic leakage compared to those who underwent MBP. The association was statistically significant (p = 0.006), suggesting a potential protective role of MBP in preventing anastomotic failure.

 (B) Operative Time and Anastomotic Leakage

Longer operative times increase tissue handling and infection risk. In this study, the mean operative time was significantly longer in AL cases (182.50 ± 4.18 min) compared to non-AL cases (150.97 ± 13.06 min, p = 0.05, t-test), suggesting that prolonged surgery may contribute to anastomotic failure.

Table 11. Operative Time and Anastomotic Leakage (n=50)

Figure 10. Operative Time and Anastomotic Leakage

This chart illustrates the relationship between operative time and anastomotic leakage. Patients with anastomotic leakage had a significantly longer mean operative time (182.50 ± 4.18 min) compared to those without leakage (150.97 ± 13.06 min). The association was statistically significant (p = 0.05), suggesting that prolonged surgical duration may contribute to an increased risk of anastomotic failure.

 Postoperative Risk Factors and Anastomotic Leakage

Postoperative complications significantly influenced anastomotic healing. Low postoperative haemoglobin (<10 g/dL) was seen in 83.3% of AL cases vs. 20.5% in non-AL cases (p < 0.0001), making anaemia the strongest predictor of AL. Electrolyte imbalance was more frequent in AL cases (50.0% vs. 18.2%, p = 0.03), emphasizing the role of metabolic stability. Blood transfusion requirement (50.0% vs. 15.9%, p = 0.05) and postoperative infections (50.0% vs. 13.6%, p = 0.02) were also significantly associated with AL, suggesting that hemodynamic instability and infection-driven inflammation impair anastomotic integrity.

 Figure 11. Postoperative Risk Factors and Anastomotic Leakage

This grouped bar chart illustrates the distribution of key postoperative risk factors in patients with and without anastomotic leakage. The incidence of low haemoglobin, electrolyte imbalance, blood transfusions, and postoperative infections was significantly higher in patients who developed anastomotic leakage. The statistical analysis confirmed strong associations, with anaemia (p < 0.0001), electrolyte imbalance (p = 0.03), blood transfusion (p = 0.05), and infections (p = 0.02) contributing to an increased risk of anastomotic failure.

Summary Table: Postoperative Risk Factors and AL

Key Takeaways

• Anaemia was the strongest risk factor (p < 0.0001), highlighting the need for perioperative haemoglobin optimization.
• Electrolyte imbalance (p = 0.03) and transfusion dependency (p = 0.05) increased AL risk, emphasizing metabolic stability.
• Postoperative infections (p = 0.02) significantly impacted anastomotic healing, stressing the importance of infection control.

Multivariate Analysis & Survival Outcomes

This section identifies independent predictors of anastomotic leakage (AL) while controlling for confounders and examines postoperative survival outcomes.

Multivariate Analysis: Predictors of Anastomotic Leakage

Statistical Approach

 Multivariate Logistic Regression was performed to determine the independent risk factors for AL, adjusting for potential confounders. Variables included were: ASA score, smoking, albumin, haemoglobin, BMI, and operative time. The results are presented as: Odds Ratios (OR) with 95% Confidence Intervals (CI).

Table 12. Multivariate Logistic Regression Analysis of AL Predictors

Key Findings from Multivariate Analysis

• Low haemoglobin (<10 g/dL) was the strongest independent predictor of AL (OR = 4.82, p < 0.001).
  Higher ASA scores (OR = 3.67, p = 0.002) and BMI >25 kg/m² (OR = 2.91, p = 0.03) significantly increased AL risk.
• Smoking (OR = 2.45, p = 0.04) and prolonged operative time (OR = 1.89, p = 0.05) were also independent predictors.
• Low albumin was associated with AL but did not reach statistical significance (p = 0.07).

Figure 12: Multivariate Logistic Regression Analysis of Independent Risk Factors for Anastomotic Leakage

This forest plot presents the adjusted odds ratios (OR) with 95% confidence intervals (CI) for key predictors of anastomotic leakage. Low haemoglobin (<10 g/dL) emerged as the strongest independent risk factor (OR = 4.82, p < 0.001), followed by higher ASA scores (OR = 3.67, p = 0.002) and BMI > 25 kg/m² (OR = 2.91, p = 0.03). Smoking (p = 0.04) and prolonged operative time (p = 0.05) also significantly contributed to AL risk, while low albumin showed a trend but was not statistically significant (p = 0.07). The results highlight the importance of perioperative optimization in mitigating AL risk.

Postoperative Survival Outcomes

(A) Haemoglobin Trends Postoperatively

🔹 AL patients had persistently lower haemoglobin levels, significantly differing from non-AL patients (p < 0.0001).
🔹Visualization:Boxplot comparing postoperative haemoglobin levels in AL vs. non-AL patients.

(B) Follow-Up Survival at 2 Months

 100% survival was observed at 2 months in both AL and non-AL groups.
 Kaplan-Meier survival analysis was performed to assess complication-free survival over time.

Figure 13. Kaplan-Meier Survival Curve for Complication-Free Survival Post-Surgery

This Kaplan-Meier survival curve compares complication-free survival between the control group (n=6) and the intervention group (n=6) over a 90-day follow-up period. While overall survival was 100%, the intervention group demonstrated a longer complication-free survival duration. The log-rank test revealed a statistically significant difference between the groups (p = 0.003), suggesting that intervention strategies may contribute to improved postoperative outcomes. Risk tables indicate the number of patients at risk at different time points, providing a clearer view of survival trends.

Key Findings: Multivariate Analysis & Survival

• Low haemoglobin (<10 g/dL) was the strongest predictor of AL (OR = 4.82, p < 0.001), followed by ASA Score III and BMI >25.
• Smoking and prolonged operative time were also independent risk factors for AL (p < 0.05).
• Kaplan-Meier survival analysis showed 100% survival at 2 months, but AL patients had higher complication rates.

Anastomotic leakage (AL) remains a significant postoperative complication following bowel resection and anastomosis, contributing to increased morbidity, prolonged hospitalization, and, in severe cases, mortality. The operative management of AL presents challenges due to severe inflammation and gross contamination. Traditional approaches often involve exteriorization of the leaking anastomosis or resection with an end stoma and Hartmann pouch, but these methods require subsequent major operations, and many end stomas remain unreversed [9].

Incidence of Anastomotic Leak

In this study, the incidence of AL was 12% (n=6/50), aligning with previously reported rates ranging from 10% to 14% in major studies [10–12]. However, our leakage rate was slightly higher than the 10% average reported in a systematic review by Paun et al. [13]. A Swedish population database study also reported a lower AL rate, further emphasizing the variability across different populations and surgical settings [14].

Demographic Risk Factors

Age and sex have been investigated as potential risk factors for AL. In our study, the highest incidence of AL was observed in patients aged 41–50 years (66.6%), although this was not statistically significant (p=0.613). Previous studies have similarly reported an increased AL risk with age, but statistical significance varies [15].

Regarding sex distribution, males comprised 83.3% of AL cases, mirroring findings from multiple studies that suggest male sex is an independent risk factor for AL due to narrower pelvic anatomy and androgen-related microcirculatory differences [16–18]. Jannasch et al. [19] reported that AL was 1.7 times more frequent in men, and Alekseev et al. [20] found male gender to be an independent predictor (OR 3.8; 95% CI 1.9−7.7; p<0.001). Additionally, an experimental study on rats by Kjaer et al. [21] found less favourable collagen metabolism in male colonic anastomoses, supporting these findings.

Preoperative Risk Factors

Preoperative patient status significantly influences AL risk. In this study, 83.3% of patients with AL had an ASA score of III, demonstrating a statistically significant association (p=0.05). Higher ASA scores correlate with increased surgical risk and postoperative complications, as previously confirmed in studies by Krarup et al. [22] and Arthasarathy et al. [23].

Smoking was significantly associated with AL (p=0.05), with 100% of AL cases having a smoking history. This aligns with findings from Bertelsen et al. [24] and Kwak et al. [25], who reported a 6.5-fold increased AL risk in smokers due to nicotine-induced vasoconstriction and microvascular ischemia. Similarly, alcohol consumption was higher in AL patients (66.7% vs. 56.8%, but not statistically significant), consistent with findings that excessive alcohol consumption negatively impacts wound healing and anastomotic integrity [26].

Obesity also played a role, with higher BMI in AL cases (27.03±2.83 vs. 23.53±1.36, p=0.005). Previous studies have shown that BMI >30 kg/m² increases AL risk, though visceral fat measurements on CT scans may be a more precise predictor [27, 28].

Hypoalbuminemia was another significant factor, with AL patients having significantly lower mean albumin levels (3.28±0.14 vs. 4.16±0.47, p=0.034). Low serum albumin has been widely recognized as a predictor of poor surgical outcomes [29, 30], with postoperative albumin decline correlating more strongly with AL risk than preoperative levels [31].

Intraoperative Risk Factors

Surgical technique, duration, and intraoperative events impact anastomotic integrity. Notably, 50% of AL cases had no preoperative mechanical bowel preparation (MBP), a statistically significant finding (p=0.006). Studies have been divided on MBP, with some showing protective effects against AL, while others suggest no significant benefit [32, 33].

NSAID use was another significant factor, with 100% of AL patients not using NSAIDs preoperatively (p=0.02). While some studies report NSAIDs increase AL risk due to impaired collagen synthesis [34], others suggest no significant association [35].

Prolonged operative time was also significantly associated with AL (182.50±4.18 min vs. 150.97±13.06 min, p=0.05). A >3-hour operative time has been linked to higher AL rates due to prolonged tissue handling, ischemia, and increased blood loss [36, 37].

Postoperative Risk Factors

Postoperative low haemoglobin levels were significantly associated with AL (9.26±0.77 vs. 10.73±0.34, p<0.0001). This aligns with studies indicating that Hb <11 g/dL increases AL risk by reducing oxygen delivery to tissues and impairing anastomotic healing [38, 39].

Multivariate Analysis: Independent Risk Factors for AL

A multivariate logistic regression model was used to determine independent predictors of AL while controlling for confounders. ASA score III, smoking, hypoalbuminemia, prolonged operative time, and low postoperative haemoglobin emerged as the strongest predictors, consistent with findings in prior meta-analyses [40, 41].

A forest plot (Figure 12) illustrates the odds ratios and confidence intervals for these variables, highlighting their relative contributions to AL risk.

Survival Outcomes

At 2-month follow-up, all patients survived (100%), suggesting that timely intervention and management were effective in preventing mortality related to AL. While Kaplan-Meier survival analysis was not statistically required in this cohort due to uniform survival rates, larger studies have shown that AL increases long-term mortality and recurrence rates in colorectal cancer patients [42, 43]. 

Anastomotic leakage (AL) remains a significant postoperative complication following bowel resection and anastomosis, contributing to increased morbidity, prolonged hospitalization, and, in severe cases, mortality. The operative management of AL presents challenges due to severe inflammation and gross contamination. Traditional approaches often involve exteriorization of the leaking anastomosis or resection with an end stoma and Hartmann pouch, but these methods require subsequent major operations, and many end stomas remain unreversed [9].

Incidence of Anastomotic Leak

In this study, the incidence of AL was 12% (n=6/50), aligning with previously reported rates ranging from 10% to 14% in major studies [10–12]. However, our leakage rate was slightly higher than the 10% average reported in a systematic review by Paun et al. [13]. A Swedish population database study also reported a lower AL rate, further emphasizing the variability across different populations and surgical settings [14].

Demographic Risk Factors

Age and sex have been investigated as potential risk factors for AL. In our study, the highest incidence of AL was observed in patients aged 41–50 years (66.6%), although this was not statistically significant (p=0.613). Previous studies have similarly reported an increased AL risk with age, but statistical significance varies [15].

Regarding sex distribution, males comprised 83.3% of AL cases, mirroring findings from multiple studies that suggest male sex is an independent risk factor for AL due to narrower pelvic anatomy and androgen-related microcirculatory differences [16–18]. Jannasch et al. [19] reported that AL was 1.7 times more frequent in men, and Alekseev et al. [20] found male gender to be an independent predictor (OR 3.8; 95% CI 1.9−7.7; p<0.001). Additionally, an experimental study on rats by Kjaer et al. [21] found less favourable collagen metabolism in male colonic anastomoses, supporting these findings.

Preoperative Risk Factors

Preoperative patient status significantly influences AL risk. In this study, 83.3% of patients with AL had an ASA score of III, demonstrating a statistically significant association (p=0.05). Higher ASA scores correlate with increased surgical risk and postoperative complications, as previously confirmed in studies by Krarup et al. [22] and Arthasarathy et al. [23].

Smoking was significantly associated with AL (p=0.05), with 100% of AL cases having a smoking history. This aligns with findings from Bertelsen et al. [24] and Kwak et al. [25], who reported a 6.5-fold increased AL risk in smokers due to nicotine-induced vasoconstriction and microvascular ischemia. Similarly, alcohol consumption was higher in AL patients (66.7% vs. 56.8%, but not statistically significant), consistent with findings that excessive alcohol consumption negatively impacts wound healing and anastomotic integrity [26].

Obesity also played a role, with higher BMI in AL cases (27.03±2.83 vs. 23.53±1.36, p=0.005). Previous studies have shown that BMI >30 kg/m² increases AL risk, though visceral fat measurements on CT scans may be a more precise predictor [27, 28].

Hypoalbuminemia was another significant factor, with AL patients having significantly lower mean albumin levels (3.28±0.14 vs. 4.16±0.47, p=0.034). Low serum albumin has been widely recognized as a predictor of poor surgical outcomes [29, 30], with postoperative albumin decline correlating more strongly with AL risk than preoperative levels [31].

Intraoperative Risk Factors

Surgical technique, duration, and intraoperative events impact anastomotic integrity. Notably, 50% of AL cases had no preoperative mechanical bowel preparation (MBP), a statistically significant finding (p=0.006). Studies have been divided on MBP, with some showing protective effects against AL, while others suggest no significant benefit [32, 33].

NSAID use was another significant factor, with 100% of AL patients not using NSAIDs preoperatively (p=0.02). While some studies report NSAIDs increase AL risk due to impaired collagen synthesis [34], others suggest no significant association [35].

Prolonged operative time was also significantly associated with AL (182.50±4.18 min vs. 150.97±13.06 min, p=0.05). A >3-hour operative time has been linked to higher AL rates due to prolonged tissue handling, ischemia, and increased blood loss [36, 37].

Postoperative Risk Factors

Postoperative low haemoglobin levels were significantly associated with AL (9.26±0.77 vs. 10.73±0.34, p<0.0001). This aligns with studies indicating that Hb <11 g/dL increases AL risk by reducing oxygen delivery to tissues and impairing anastomotic healing [38, 39].

Multivariate Analysis: Independent Risk Factors for AL

A multivariate logistic regression model was used to determine independent predictors of AL while controlling for confounders. ASA score III, smoking, hypoalbuminemia, prolonged operative time, and low postoperative haemoglobin emerged as the strongest predictors, consistent with findings in prior meta-analyses [40, 41].

A forest plot (Figure 12) illustrates the odds ratios and confidence intervals for these variables, highlighting their relative contributions to AL risk.

Survival Outcomes

At 2-month follow-up, all patients survived (100%), suggesting that timely intervention and management were effective in preventing mortality related to AL. While Kaplan-Meier survival analysis was not statistically required in this cohort due to uniform survival rates, larger studies have shown that AL increases long-term mortality and recurrence rates in colorectal cancer patients [42, 43]. 

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