The incidence of benign diseases of the large intestine, including diverticulitis, vascular disease, and trauma, as well as malignant tumors is likely increasing as a result of the changes in dietary habits and the increase in life expectancy [1,2].

Surgical treatment is necessary for colorectal diseases accompanied by perforation, obstruction, ischemic necrosis, and massive hemorrhage, despite the use of nonsurgical treatment as a result of advancements in endoscopic technology, and antibiotics. The majority of these cases require emergency surgery [3,4].

In previous studies, it has been reported that the mortality rate following emergency colonic surgery is 10%–25% and the incidence of complications is 30%–50% [5]. The high mortality and complication rates are because preoperative risk assessment and preoperative treatment are not properly performed, and many patients often undergo surgery although they have demonstrated poor vital signs before surgery [6,7]. Mortality and complication rates are also affected the aging population, and the relatively large number of patients with underlying diseases.

Adequate critical care support and resources are necessary during the patient’s recovery period following surgery [8]. This includes medical equipment for intensive care units [including mechanical ventilators and deliver of Continuous Renal Replacement Therapy (CRRT)], experienced staff (including nurses, and intervention teams), and supporting departments to consult with. This is a burden on medical institutions and surgeons, and the likelihood of needing to use mental compulsion for the patients welfare, and the legal issues a surgeon may encounter is also on the rise as a result of high postoperative mortality rates [9].

The prognosis in colorectal emergency surgery is influenced by a variety of factors, including the diversity of the disease, the characteristics of the patient group, and the clinical features such as perforation, hemorrhage, obstruction, and ischemia. Consequently, it is exceedingly challenging to predict the outcome of colorectal disease following emergency surgery [10,11].

This study aimed to identify the predictive risk factors, following colorectal emergency surgery, associated with mortality, by comparing and analyzing survivor and non-survivor data.

This was a retrospective study that analyzed clinical information collected on patients who were diagnosed with colorectal disease and underwent emergency surgery at Pusan National University Yangsan Hospital from June 2019 to December 2021. There were 164 patients included in the analysis who visited the emergency room, required emergency colorectal surgery (within 24 hours), and underwent emergency colorectal surgery performed by a single surgeon. Excluded from this study were pediatric patients, appendicitis-related surgery, stoma-only surgery, and cases of reoperation due to complications following elective surgery were. This study was approved by the Institutional Review Board of Pusan National University Yangsan Hospital (IRB no.: 55-2024-092).

The patient’s age, gender, American Society of Anesthesiologist (ASA) classification, cause of disease, type of surgery, presence of underlying disease, initial white blood count (WBC), C-reactive protein (CRP) level, hospitalization period, complications, and mortality rates were analyzed. Postoperative complications were classified into sepsis, pneumonia, and surgical site infection, and there was further evaluation using the Clavien-Dindo (CD) classification. In addition, the Mannheim peritonitis index (MPI) score was used to predict the prognosis of patients with colorectal disease. The MPI is a scoring system established in 1983 that predicts the severity and mortality of peritonitis by considering age, sex, organ dysfunction, and peritoneal exudate character. It is a widely applied index because it is simple and quick measure to predict mortality during surgery.

Among the clinicopathological factors related to the patients and their surgery, the independent samples t test was used to compare continuous variables, including age, WBC count, CRP, and length of surgery, between the survivor and non-survivor groups. Categorical variables, such as sex, ASA classification, comorbidities, surgical indication, CD classification, and complications, were analyzed using the chi-square test to assess whether there was an association with survival status. Statistical significance was reached when p < 0.05 (2-tailed). Only univariate analysis was performed in this study.

A total of 164 patients underwent emergency colorectal surgery during the study period. There were more males (90 men) than females (74 women). The age distribution showed that 86 patients were ≥ 70 years, and 78 patients were < 70. Using to the ASA Physical Status Classification Grade, 89 patients (54.3%) were classified as Grade 3 or higher. Preoperative initial lab results indicated that leukocytosis was observed in 40.2% of the patients, and leukocytopenia in 14.0%. The average CRP level, which increases during inflammatory responses, was 10.0 ± 10.8 mg/dL. Regarding comorbid conditions, 42 patients (25.6%) had 2 or more comorbidities, 54 patients (32.9%) had 1 comorbidity, and 68 patients (41.5%) had no comorbidities. The most common site of colonic lesions was the sigmoid colon (72 patients, 43.9%), followed by the ascending colon, rectum, and descending colon. Perforation was the most common type of lesion (88 patients, 53.7%), and 35 patients had lesions with 2 or more characteristics among perforation, obstruction, and ischemia. The MPI score measured during surgery was most commonly in the range of 14–21 points (50 patients, 30.5%), with 49 patients scoring ≥ 30 points (Table 1).

The most common underlying condition was malignancy, which affected 86 patients. The surgical procedure was selected in accordance with the location of the lesion and the intraabdominal condition. Postoperative complications were categorized using the CD classification, resulting in 19 patients with Grade 2, 21 with Grade 3a, 5 with Grade 3b, 15 with Grade 4a, and 24 with Grade 5 postoperative complications. The average total length of hospital stay following surgery was 18.0 days, and 24 patients (14.6%) died postoperatively (Table 2).

To identify factors influencing mortality, statistical analysis was conducted using Version 21 SPSS (SPSS Inc., Chicago, IL, USA) and patient data were assigned to survival and non-survival groups. There were no significant differences between the survival and non-survival groups in terms of gender (p = 0.269), age (p = 0.514), preoperative first WBC (p = 0.236), CRP level (p = 0.659), and location of lesion (p = 0.571). However, ASA classification, comorbid diseases, indication for surgery, CD classification, and the MPI scores had a statistically significant impact on mortality rates (Tables 3 and 4).

Specializing in colorectal emergency surgery comes with significant burdens [12]. Surgeons must contend with the high complexity of the procedures, the difficulties in postoperative care, and the legal risks associated with high mortality rates [13,14]. Moreover, the nature of emergency surgery leads to irregular working hours and challenging conditions. Nevertheless, the sense of fulfillment and duty in saving lives drives many surgeons to persevere despite these difficulties. Among the challenges, the inherently high mortality rate of these conditions is particularly tough for those dedicated to colorectal emergency surgery [15,16].

The perioperative mortality rate for colorectal emergency surgeries has been reported to be around 10%–25% in studies from 1990 and 2000 [5]. In this current study it was determined that there was a mortality rate of 14.6% amongst the 164 patients who underwent colorectal emergency surgery. However, in South Korea, sufficient data on perioperative mortality rate for colorectal emergency surgery is lacking [17,18]. While risk factors and evaluation criteria for general postoperative mortality are known, it is expected that there are significant differences in colorectal emergency surgery mortality. Understanding these differences is crucial for reducing postoperative mortality.

Typically, postoperative mortality risk assessment involves evaluating the patient’s age, comorbid conditions, and ASA classification [19,20]. Comparing data from the survival and non-survival groups, there was no significant difference in mortality rates between patients aged ≥ 70 and those < 70. However, patients with 2 or more comorbid conditions, such as diabetes, hypertension, and renal failure, showed higher mortality rates in the non-survivor group than the survivor group. The ASA classification is used to predict patient outcomes during and after surgery. The results from this current study also indicated that patients classified as an ASA IV or higher had the highest mortality rate in the study, making it a useful predictor of postoperative mortality in colorectal emergency surgery. However, unlike elective surgery, emergency surgery often proceeds without the complete preoperative preparation and evaluation, and this limits the healthcare team in their ability to fully assess the patient prior to surgery. Therefore, it was hypothesized that using intraoperative, objectively measurable information to predict postoperative mortality would be more advantageous in the context of emergency surgery. Surgical indications, lesion locations, and the MPI scores were investigated to study their impact on postoperative mortality. No significant difference in mortality was observed based on the location of the lesions, and there was no difference in the results between the left colon and the right colon. This is thought to be attributable to the short-term postoperative period which did not include a long-term prognosis of mortality and complication rates. However, indications and the MPI scores showed statistically significant differences between mortality and survival groups. Among patients with perforations, 8 out of 88 died, while there were no deaths among those with obstructions alone. Mortality was high among patients with ischemic necrosis, likely due to the colon’s vulnerability to ischemia. In cases of systemic hypoperfusion, the colon may necrotize first, leading to symptoms and continued systemic issues despite surgery, thus increasing mortality. Patients with multiple combined indications also showed high mortality. The MPI, a simple scoring system predicting outcomes in patients with peritonitis, assigns points based on 8 criteria [21]. It was easy to measure during surgery, and most deaths occurred in patients with the MPI score > 30. Patients with perioperative hypotension requiring vasopressors had higher postoperative mortality and complication rates. Patients exhibiting postoperative septic shock also had a statistically significantly higher mortality rate.

High mortality and complication rates following colorectal emergency surgery are more influenced by patient factors than by surgical quality or duration [22]. For any major surgery or sepsis, elderly patients with comorbid conditions require appropriate postoperative intensive care to improve their outcomes [23]. This requires a sufficient number of Intensive Care Unit beds and skilled nursing staff. In addition, postoperative major complications (including pneumonia, infective fluid collections, and renal failure, necessitating mechanical ventilation, CRRT), need an intervention team to deliver treatment. Diagnostic imaging tools like computed tomography and ultrasound machines are also essential. However, many healthcare facilities lack adequate resources and staff [24]. Thus, effectively categorizing high-risk and low-risk patients, and the allocation of resources and personnel covering intensive care for high-risk patients is necessary for efficient utilization of medical resources. For patients with high MPI scores or ischemic necrosis (or combined indications), arranging intensive care postsurgery and preparing the necessary medical equipment is advisable.

In this current study, colorectal emergency surgery due to colorectal cancer was the most common (52.4%) cause, often presenting as obstructions or perforations. Obstructions frequently involved ischemic necrosis. In South Korea, colorectal cancer screening is conducted using fecal occult blood tests. Given that a colonoscopy is the best diagnostic method for detecting colorectal cancer, changes in the screening approach may be necessary.

This current study determined that 14.6% of patients undergoing colorectal emergency surgery died during hospitalization. Factors assessed using the ASA classification, surgical indications, comorbidities, and the MPI scores statistically significantly influenced postoperative mortality. Particularly, the MPI scores which can be measured during surgery and provides an objective criterion for predicting postoperative mortality in emergency surgery scenarios where preoperative evaluation may be insufficient. Identifying patients with these risk factors for postoperative intensive care could help allocate limited resources more effectively and reduce mortality rates.

If it were possible to categorize a patient undergoing emergency colorectal surgery who was expected to have a high risk of mortality, before the surgery, it would allow for more efficient allocation of limited intensive care resources. Adequate intensive care following surgery is particularly beneficial in reducing mortality rates. Among the factors associated with mortality following colorectal surgery, the MPI score has proven to be particularly significant in predicting mortality. Given the nature of emergency surgery, where preoperative evaluation is challenging, the MPI score could be valuable as it allows the surgeon to quickly and easily assess the patient during surgery.