Complications During Surgical Treatment of Incarcerated Inguinal Hernia

Introduction: An incarceration of inguinal hernia is a life-threatening condition and represents the most frequent complication, particularly in the elderly patients. It may compromise vascularisation of the contents of the hernia. A surgical treatment of the incarcerated inguinal hernia represents one of the most frequent surgical interventions in elderly patients and it grows proportionally with the age. Aim of the Study: The aim of the study is to investigate some of the factors that may have an impact on the incarcerated inguinal hernias surgical treatment outcome in elderly patients. Patients and Methods: The study included 149 patients classified in two groups: the study group (> 60 years of age), which included 96 patients, and the control group (≤ 60 years of age) , which included 53 patients, treated in the period from January 1st, 2012 to December 31st, 2016 at the Clinic of General and Abdominal Surgery UCC RS Banja Luka. Results: Most of the patients had right inguinal hernia (51.16% in the study group, 60.37% in the control group). 82 patients (85.41%) of the study group suffered from some of the accompanying chronic diseases, opposite to 20 patients (37.73%) of the control group. Polypropylene mesh was implanted in 105 (70.47%) patients, while the tension technique was performed in 44 (29.53%) patients. The duration of incarceration longer than 24 h (p=0.015), previous abdominal surgery (p=0.001), the American Society of Anaesthesiologists physical status classification system (ASA classification) (p=0.033) and the presence of chronic diseases (p=0.01) appeared to be statistically significant risk factors for performing intestinal resection in the study group, while in the control group, they represented risk factors, but not at the level of statistical significance (p > 0.05), except for the duration of incarceration (p=0.007). A higher ASA stage (p=0.001), is the most important risk factor for lethal outcome in both groups of patients. Conclusion: Incarcerated inguinal hernia is a very serious and demanding surgical problem, particularly in elderly patients. A higher ASA score and the presence of bowel resection are the most important risk factors related to very difficult complications.


Introduction
Due to abdominal wall weakness and conditions that increase intra-abdominal pressure, external hernia is more frequently seen in elderly patients. [1][2][3][4] The estimated incidence of the inguinal hernia in patients more than 60 years old is 13 per 1000. 5 Incarcerated external hernia repairs are one of the most common emergency procedures performed in elderly patients. 6 Males predominate among the patients up to 75 years of age, while females prevail in the older age. 7,8 The most recent data indicate that incarcerated inguinal hernia account for about 20% of all small bowel obstructions. Due to the fact that up to 30% of bowel incarcerations require intestinal resection, it is also associated with significant morbidity and mortality. 5 Up to 75 years of age, 10-15 % of men underwent surgical treatment of inguinal hernia.

Aim of the Study
The aim of the study is to examine some of the most important factors that may affect the outcome of incarcerated inguinal hernias surgical treatment in elderly patients.

Patients and Methods
SThe study included 149 patients that underwent surgery in the period from January 1 st , 2012 to December 31 st , 2016 at the at the Clinic of General and Abdominal Surgery UCC RS Banja Luka. The patients were divided into two groups: a study group (> 60 years of age) and a control group (≤ 60 years of age). During the research, the following parameters were followed: age, gender, type of incarceration (direct/indirect), the ratio of right to left incarcerated inguinal hernia, related chronic diseases, the duration of incarceration (0-24 h, > 24 h), The American Society of Anaesthesiologists (ASA) classification 6,16,20 , type of surgical procedure (tension technique or tension-free technique).
In statistical analysis for comparing values of study and control group, parametrical tests (Student's t-test and ANOVA) were used. Analysis of variables not sorted by the type of normality was made by comparing the nonparametrical tests (Mann-Whitney, U-test, Spearmen Correlation, χ2 test, Fisher exact probability tests the null hypothesis). Analysis of the influence of some factors was made by inivariant logistic regression and the analysis of survival was made through Cox Regression models, where the invariant ''Enter'' method was used to determine hazard rate (HR). By means of this method (Enter), the level of risk factors was defined. The statistical analysis was implemented by software package SPSS (version 19) with a statistical probability of p < 0.05.

Results
The study included a total of 149 patients of whom 96 were in the study group and 53 in the control group. The patients in the study group (the average age of 68.23 ± 7.11 years), were significantly older than those in the control roup whose average age was 51.47 ± 13.87 years.
As expected, there was a statistically significant difference in the age of the study group and control group (p = 0,008). Out of 96 patients in the study group, 19 had direct and 75 indirect hernia. Out of 56 patients in the control group, 8 had direct and 45 indirect hernia. In both analyzed groups, no statistically significant differences was noticed in the frequency of occurence of the hernia (χ2: p > 0,5). The highest number of patients had a right inguinal hernia (84 or 56.38 % of the total number of patients, from which 52 or 61.9 % in the study and 32 or 38.1% in the control group). 82 patients in the study group (80.39 %) had some chronic diseases, which was significantly more than in the control group -20 patients (37.73 %). (Table 1 Table 3.). Table 4. shows the summary statistics of Cox regression model and log rank test of patients survival length. The patients' age in the study group did not represent a statistically significant risk factor for lethal outcome (p = 0,657). The length of survival in both groups did not seem to differ in age (p = 0,584). In the study group, gender did not represent a statistically significant risk factor for lethal outcome (p = 0,542). Also, there was no difference between the groups in terms of the length of survival by gender (p = 0,384). By increasing ASA stage for one, a chance for lethal outcome was increased 8,541 times at the level of significance (p = 0,016). The presence of intestinal resection was a statistically significant risk factor for lethal outcome, increasing the chance 7,358 times (p = 0,002). The duration of incarceration over 24h was a statistically significant risk factor, increasing the chance by 26 times (p = 0,04) and the patients with resection had significantly shorter survival time than the patients without resection (p = 0,043).

Discussion
Strangulation hernia is a condition in which the hernia cannot be returned to the abdomen. By putting emphasis on the increased risk of intestinal obstruction, strangulation incarceration is of a great importance. 8 Incarcerated external hernias are the second most important cause of intestinal obstruction. 9 In elderly people, about 40 % of inguinal hernias are surgically treated due to incarceration or intestinal occlusion. Although some earlier studies have presented data that only 5 % of all inguinal hernias require urgent surgical care 10 , others have suggested that this percentage is slightly higher and amounts up to 13 %. 11 Since the anterior abdominal wall hernia incarceration, followed by incarceration of intestinal curves, is associated with high percentage of morbidity and mortality [10][11][12] , urgent surgical intervention is necessary. There is a generally accepted view that hernia should be electively managed in order to avoid later complications. 13 However, many patients are undiagnosed, or consciously reject the proposed surgery, that resulting in occurrence of many emergency surgeries, because of ''neglected" cases of hernia. The incarceration percentage increases also by the waiting lists for elective surgery 1 , as well as the fact that non-surgical medical staff did not provide enough information to the patients regarding the danger of incarceration. There were no significant differences in the occurrence frequency of inguinal hernia between the groups, as reported also by other published studies. 1,11 The published studies have shown that indirect herniasdominate over the direct ones in the proportion ranging from 7 : 3 : 10 : Our study has also shown that there was not more frequent occurrence of indirect hernia than direct incarcerated inguinal hernia concerning sex. Another important factor, contributing to the unwanted outcome in the patients with incarcerated inguinal hernia, is related to comorbidity of chronic diseases. 17,18 The chronic diseases are even more important factor when talking about mortality. 19 Most of the patients in the study group had some chronic diseases, that is, 82 (85.41 %), which was statistically more significant that 20 (37.73 %) patients in the control group. Symptoms duration in the study group was accompanied by incarceration duration and lasted from one to three days. Duration increases with the age, which could be observed in other studies, too. 1 Late hospitalization is generally considered as an important factor for determining the level of intestinal resection and subsequent morbidity and mortality. 10,[20][21][22] Incarceration and strangulation with or without intestinal obstruction are major complications. 23 Roughly speaking, about 15 % of all patients with incarcerated intestinal curve require resection due to intestinal necrosis caused by strangulation. 20,24 Manual reposition may be the method of choice without resection in incarcerated inguinal hernia, although there are no strict criteria to clearly differentiate strangulation, except for the obvious peritonitis. 24 Higher number of patients studied in both groups who were without intestinal resection and had incarceration that lasted less than 24h (p = 0,002) is statistically significant.
Our study showed that, according to Cox's regression model and log-rank test on the patients with and without intestinal resection, the presence of intestinal resection was a statistically significant risk factor for lethal outcome, increasing the chance 7,4 times and the patients with resection had a significantly shorter survival time than those without resection. Open tension-free technique was the most common surgical technique type as in all previous studies, [25][26][27] and in both tested groups of our study.
This technique contributed to managing a total of 105 (70.47 %) patients. Considering a general attitude that synthetic material should not be implanted in patients younger than 30 years of age, because of the netting deformation during a young organism development, as well as because of the surgeons' fear to implant synthetic material in intestinal resection cases due to possible complications, we can argue with the level of error (p = 0,003), that much higher number of patients in the control group -44 (83.02 %) had a built-in synthetic material, while the number of patients in the study group was 61 (63.55 %). In previous studies on patients with incarcerated inguinal hernias, it has been observed that a high ASA score is an independent predicting factor for small bowel gangrene. 28 Alvarez et al. 19 not only confirmed the higher rate of complications, but also showed a higher rate of mortality in patients with higher ASA grade. In our study, ASA grade was a risk factor for performing intestinal resection, but not at the level of statistical significance.

Conclusion
Our study showed that the incarcerated inguinal hernia is a very serious problem. If the inguinal hernia is not operated and managed at the right time, there is a risk that easy surgical problems may lead to various serious complications with a lethal outcome. The risk is higher in elderly patients because of the presence of associated chronic diseases. Statistically significant risk factors for performing intestinal resection in the study group patients were duration of incarceration longer than 24 h, previous abdominal surgery, higher ASA classification, whereas in the control group, the only risk factor was duration of incarceration more than 24h.