The medical charts of 145 patients, who underwent colonic perforation surgery between April 2010 and May 2019 in a single center, Dankook University Hospital, were reviewed retrospectively. The exclusion criteria were perforations caused by a malignancy (23.4%), trauma (20.0%), diverticulitis (17.2%), iatrogenic causes (9.6%), necrosis following vasculopathy (4.1%), inflammatory bowel disease (2.1%), anastomosis leak-age after colonic surgery (1.3%), and idiopathic causes (6.9%) (Table 1). After applying the exclusion criteria, 22 cases were enrolled in the study based on the radiologic features, intra-operative findings, and histopathological criteria (Table 2) (Fig. 1).⁶ The Institutional Review Board of Dankook University Hospital reviewed and approved this study (IRB No. 2020-07-020).

Data on the demographic parameters, perioperative findings, and pathology examination results were gathered for analysis. The demographic parameters included age, sex, BMI, comorbidities, chronic constipation, and bedridden status. The preoperative vital signs, laboratory and radiology findings, intraoperative findings, postoperative complications, and mortality were reviewed as the perioperative data. APACHE II scores were calculated as described by Knaus et al.⁷, and the present study referred to Ochiai et al.’s study⁸ for the sequential organ failure assessment (SOFA) scores. Mortality was defined as death within three months postoperatively. Moreover, the time it took to start the operation from symptom onset was also included.

A Chi-squared and Fisher’s exact test were used to analyze the categorical variables, whereas a Mann-Whitney test was applied to compare the continuous variables. Logistic regression analysis was performed to identify the risk factors for postoperative death. A p-value of more than 0.05 was considered significant. All analyses were performed using the IBM SPSS Statistics 20.0 software (SPSS Inc., Chicago, IL, USA).

Among all the patients enrolled (n=22), the mean age was 75.7±9.0 years, with a female predominance (female patients, n=19, 86.4%) and a mean BMI of 20.42±3.34 kg/m². Patients with two or more diseases, including diabetes mellitus, hypertension, ischemic heart disease, cerebrovascular accident, and chronic kidney disease treated with dialysis, were 12 (54.5%), whereas two patients had none of these diseases. Twenty-one patients (95.4%) were identified as having the physical status of American Society of Anesthesiologists (ASA) class 3 or above in this study. Among the patients, 16 (72.7%) had chronic constipation with medications and five (22.7%) were bedridden. Fifteen patients had oral laxatives, such as magnesium hydroxide and lactulose syrup, for more than one month. Only one patient with constipation was medicated for 2 weeks. Three of five bedridden patients had chronic constipation and received rectal stimulation by suppositories or enema.

Fourteen patients (63.6%) had symptoms for more than a day, and the mean time from symptom onset to operating room transfer was 25.3±15.18 hours. A perforation site assessment revealed the sigmoid colon (n=16, 72.7%) to be the most common site, followed by the recto-sigmoid junction (n=3, 13.6%), rectum (n=2, 9.1%), and descending colon (n=1, 4.5%). The mean perforation size was 2.3±1.1, and only one patient had multiple perforations (three sites).

The patients were divided into the following two groups according to their survival after surgery: alive group A and dead group B. The alive and dead groups were statistically similar in terms of sex (female sex in group A 93.3% vs. 71.4% in group B; p=0.227), age (mean 77.0±9.0 years vs. 73.0±9.1 years; p=0.407), and BMI (mean 20.15±1.94 vs. 21.02±5.45 kg/m²; p=1.000) (Table 3). There were no differences in co-morbidity ≥2 (46.7% vs. 71.4%; p=0.381) and chronic constipation (27.3% vs. 72.7%; p=0.334) between the two groups, but the rate of preoperative bedridden status was significantly higher in group B (6.7% vs. 57.1%; p=0.021).

The time from symptom onset to surgery was similar in the two groups (mean 24.3±16.7 hours vs. 27.5±11.9 hours; p=0.616). Regarding the intraoperative findings, except for three patients who underwent a loop colostomy without resection, all surgeries (n=19, 86.4%) were performed using Hartmann’s procedure. The perforation size was similar in both groups (mean 2.3±1.3 cm vs. 2.2±0.7 cm; p=0.535).

The preoperative initial vital signs, including the mean arterial pressure, heart rates, respiratory rates, and body temperature, were similar in the two groups (Table 4). Regarding the initial laboratory findings, most of the values were similar in both groups, but the serum lactate levels were significantly higher in group B (2.96±3.17 mmol/L vs. 5.22±4.50 mmol/L; p=0.021).

An analysis of the postoperative mortality causes revealed septic shock (n=4) to be the most common cause, and the mean postoperative hospital stay of deceased patients was 8.7 days. Other reasons for death were hospital-acquired pneumonia (n=2) and acute cerebral infarction (n=1).

Univariate analysis revealed the factors associated with an increased risk of death in the postoperative period: immobility, SOFA scores, and serum lactate levels of more than 2.0 mmol/L (Table 5). Multivariate analysis revealed abnormal lactate levels to be the only factor related to mortality (hazard ratio 16.50, 95% CI 1.48-183.07, p=0.022).

Furthermore, two prognostic scoring systems were used, including APACHE II score and SOFA score. On the other hand, both scoring systems were similar in the two groups according to the multivariate analysis.

SPC is rare and commonly observed in elderly adults, particularly those with chronic constipation. Fecaloma from chronic constipation, which may cause SPC, expands the large bowel lumen gradually, and increases the intraluminal pressure, which results in a decrease in blood supply to the bowel wall. If not treated appropriately and the condition continues, bowel wall ulceration or perforation can occur due to ischemia.¹ This is observed frequently in the sigmoid colon at a rate of 47%, followed by the rectosigmoid colon (30%) and other parts of the colon (33%).¹¹

In the sigmoid and the rectosigmoid segments, the liquidity of feces is low, blood circulation is weak, and there is an increase in pressure due to the narrowing of the intraluminal diameter of the bowel.¹² In a systematic review, 111 out of 137 (72.7%) SPC patients had chronic constipation,³ whereas in the present study, 16 out of 22 patients (72.7%) had preoperative constipation.

Except for chronic constipation, the previously identified SPC risk factors included female sex, old age, nursing facility residence, use of constipation medicine (opiates, non-steroidal anti-inflammatory drugs, anticholinergics, tricyclics), and evidence of fecal impaction.^3,13-16

In this study, 86.4% of patients were female. Nam et al.⁴ analyzed SPC for the first time in South Korea; all eight enrolled patients were female. This trend can be explained by the following: chronic constipation is more common in the female population, and the average age of women was higher than that of men in the cohort. Women are 2-3 times more likely to have constipation than men in terms of prevalence or physical symptoms. Various theories have been proposed to explain this phenomenon. One theory states that this phenomenon is caused by a slower gut transit in women due to the changing levels of progesterone and estrogen, or damage to the pelvic floor in a women’s obstetric history.¹⁷ On the other hand, the exact cause of the higher likelihood of constipation in women is unclear. Several individuals had undergone recent surgical procedures, which may be a unifying etiology, by exacerbating constipation and contributing to nursing home stays and opiate use.

The present study showed that the patients’ mean age was 75.7 years, and the rate of emergency surgery was 100%, but the mortality rate was not higher in patients aged over 75 years. Emergency surgery is associated with high mortality rates and remains a considerable global disease burden.¹⁸ Moreover, evidence has shown that older patients have a poorer prognosis postoperatively, with the mortality rates of patients aged over 74 years being twice that of patients aged 65-74 years in one UK study.¹⁹ Physiological reserves, which are robust in younger populations, are diminished significantly in elderly patients, and cardiovascular, pulmonary, endocrine, and renal comorbidities are common. The postoperative prog-nosis may be poor, given that most SPC surgeries were performed for elderly patients in emergency settings.

Except for one patient with ASA class 2, most of the patients were identified as having ASA class 3 or 4. Univariate and multivariate analyses of emergency surgical patients and mortality revealed the ASA class to be a good predictor of death postoperatively.²⁰ On the other hand, this is subjective and may be applied inconsistently by different anesthetists. The presence of underlying chronic conditions may deteriorate the prognosis of patients undergoing emergency surgery and may be responsible for the increased perioperative risk and mortality. The present study showed that comorbidity was not a significant prognostic factor for patients with SPC in univariate analysis (p=0.286).

Univariate analysis revealed the bedridden status before surgery to be associated with mortality after surgery (p=0.023). One recent US study developed a prediction model based on a nationwide dataset.²¹ A combination of risk factors associated with a more than 10% probability of survival included patients aged more than 90 years, an ASA score of 5, septic shock, and dependent functional status.

Neurological decline resulting in dementia and immunodeficiency, further complicates the diagnosis of intra-abdominal sepsis, often resulting in delays in presentation and diagnosis. Elderly or immobile patients would have recognition deficiency, dementia, and difficult communication. Therefore, some invasive procedures must be avoided. Furthermore, an enema procedure may cause colonic wall ulceration or perforation due to collisions with hard stools.²² Therefore, the role of enemas or suppositories in causing perforation and mortality must not be disregarded.

In this analysis, the times from the onset of symptoms to the transfer to admission or operating rooms were similar in the two groups. The long time interval from symptom onset to hospital admission and severe intra-abdominal contamination, resulting in increased evaporative losses and ex-tensive resuscitation, was associated with higher rates of postoperative complications.^23,24 Fukuda et al.²⁴ reported that the prognosis of patients admitted after more than 24 hours after symptom onset worsened compared to that of patients admitted within 24 hours.

Given that elderly patients with acute abdominal disease tend to have a delayed diagnosis, surgical treatments, rapid access to the hospital, adequate diagnostic measures, and quick and proper decision-making are required to prevent postoperative complications and improve the prognosis.

The systemic inflammatory response syndrome criteria assess the body temperature, heart rate, respiratory status, and leukocyte count. There were no differences in these factors. Several studies have shown that systemic inflammatory response syndrome factors cannot predict pathological changes, such as organ failure and acute circulatory failure. On the other hand, the practicality of the risk number score systems has been reported in this field. Acute physiology and chronic health evaluation II (APACHE II) scores are used as an index for patient severity assessments when admitted to the intensive care unit. Knaus et al.⁷ developed the APACHE II scoring system in 1985, which is comprised of 12 parameters, including blood pressure, body temperature, respiratory rate, and several laboratory data. The SOFA scores quantify the degree of organ failure and determine the mortality rate based on six aspects, including the function of respiratory, coagulation, cardiovascular, and central nervous systems as well as renal and hepatic functionalities.⁸ Komatsu et al.²⁵ reported that the mortality rate was significantly higher in patients with higher APACHE-II and SOFA scores than in patients with colonic perforation. In the present study, there were no significant differences in the APACHE II and SOFA scores between the two groups.

On the other hand, the preoperative serum lactic acid levels were significantly higher in patients who did not survive than in those who did. The serum lactic acid levels reflect organ failure owing to the lack of tissue oxygenation. Therefore, they are used for a prognostic assessment of septic shock and acute respiratory distress syndrome and are useful for determining the therapeutic outcomes and changes in the pathological conditions. Many studies have reported a higher mortality associated with acidosis caused by elevated lactic acid levels than acidosis caused by other underlying causes in severe illness.^26-28 In terms of colonic perforation, one study reported that the postoperative arterial blood lactic acid levels are useful for predicting the mortality rates.²⁹

The present study had several limitations. First, this was a retrospective study performed in a single center. Therefore, selection bias may be inevitable. Obtaining accurate in-formation in emergency and operating rooms is difficult because of the retrospective nature of the study. Second, the number of enrolled cases was small (n=22), so generalizing these results to the entire population should be carefully conducted. Third, other factors associated with a postoperative prognosis, such as mental status, operative time, grade, or type of complications, were not adjusted in this study. SPC is prevalent in older patients and women with chronic constipation. Preoperative abnormal serum lactate levels are a postoperative mortality risk factor for stercoral perforation. Further research will be needed to identify the postoperative prognostic SPC factors.