Stability in incidence of acute appendicitis. A population-based longitudinal study

Hospitalization Trends for Acute Appendicitis in Spain, 1998 to 2017

The incidence of acute appendicitis decreased in Western countries from 1930 to at least the early 1990s, when epidemiological data started becoming scarcer. This study aimed to assess the trend in annual hospitalizations for acute appendicitis in all people Spain for a 20-year period between 1998 and 2017. This observational study analyzing direct age-standardized hospital admission rates by gender and age group (0–14 years, 15–34 years, 35–44 years, 45–64 years, and ≥65 years). Joinpoint regression models were fitted to evaluate changes in trends. There were 789,533 emergency hospital admissions for acute appendicitis between 1998 and 2017: 58.9% in boys and men and 41.1% in girls and women. Overall, there was a significant increase in admissions for this cause from 1998 to 2009, with an annual percent change (APC) of 0.6%. Following the peak in 2009, admission rates decreased by around 1.0% annually until 2017. The length of hospital stay gradually decreased from 4.5 days in 1998 to 3.4 days in 2017. The trends in hospital admissions for acute appendicitis in Spain changed over the study period, decreasing from 2009, especially in people younger than 35 years.

Changes in Incidence and Management of Acute Appendicitis in Children-A Population-Based Study in the Period 2000-2015

INTRODUCTION

 Recent studies suggest that the epidemiology and management of appendicitis have changed during the last decades. The purpose of this population-based study was to examine this in the pediatric population in Denmark.

MATERIALS AND METHODS

 Data were retrieved from the Danish National Patient Registry, the Danish Civil Registration System, and the Statbank Denmark. Patients aged 0 to 17 years diagnosed with appendicitis and appendectomized during the period 2000 to 2015 were included. The primary outcome was the annual incidences of appendicitis. Secondary outcomes were the annual percent of patients with appendicitis having a laparoscopic appendectomy, delay from admission to surgery, length of postoperative hospital stay, and 30-day postoperative mortality.

RESULTS

 A total of 24,046 pediatric cases of appendicitis were identified. The annual incidence steadily declined until 2008 (-29%, all ages) and then remained stable. The surgical approach of choice changed from being open appendectomy in 2000 (97%) to laparoscopic appendectomy in 2015 (94%). Simultaneously, the duration of postoperative hospital stay declined from 41 hours (median) to 17 hours. Delay from admission until surgery did not change during the period. Only one child died within the 30-day postoperative period.

CONCLUSION

 In accordance with other recent studies from Western countries, we found significant changes in the incidence of acute appendicitis including a decline in all age groups except those below 5 years of age, a shift toward laparoscopic appendectomy, and decreasing time spent in the hospital during the years 2000 to 2015.

Acute Appendicitis: Trends in Surgical Treatment

BACKGROUND

Appendectomy is the gold standard for treatment of acute appendicitis. However, recent studies favor primary antibiotic therapy. The aim of this observational study was to explore changes in the numbers of operations for acute appendicitis in the period 2010-2017, paying special attention to disease severity.

METHODS

Data from diagnosis-related group statistics were used to analyze the trends, mortality, and complication rates in the surgical treatment of appendicitis in Germany between 2010 and 2017. All cases of appendectomy after a diagnosis of appendicitis were included.

RESULTS

Altogether, 865 688 inpatient cases were analyzed. The number of appendectomies went down by 9,8%, from 113 614 in 2010 to 102 464 in 2017, while the incidence fell from 139/100 000 in 2010 to 123/100 000 in 2017 (standardized by age group). This decrease is due to the lower number of operations for uncomplicated appendicitis (79 906 in 2017 versus 93 135 in 2010). Hospital mortality decreased both in patients who underwent surgical treatment of complicated appendicitis (0.62% in 2010 versus 0.42% in 2017) and in those with a complicated clinical course (5.4% in 2010 versus 3.4% in 2017).

CONCLUSION

Decisions on the treatment of acute appendicitis in German hospitals follow the current trend towards non-surgical management in selected patients. At the same time, the care of acute appendicitis has improved with regard to overall hospital morbidity and hospital mortality.

Evaluation of Preoperative Clinical and Serological Determinations in Complicated Acute Appendicitis: A Score for Predicting Complicated Appendicitis

BACKGROUND

To analyze whether clinical and analytical parameters differ according to histopathology in cases of acute appendicitis (AA).

METHODS

This is a retrospective, observational study including patients (>14 years of age) admitted for suspicion of AA from 1 April 2014 to 31 July 2016. Histopathology was divided into complicated (including perforated and gangrenous AA) and uncomplicated appendicitis (phlegmonous). Sex, age, temperature of patients on admission to the Emergency Department, symptom duration, preoperative white blood cell (WBC) count, neutrophil percentage, mean platelet volume (MPV), platelet distribution width (PDW), C-reactive protein (CRP) and hospital stay were compared in the two groups.

RESULTS

Three hundred and thirty-five patients were analyzed, and 284 were included. Appendicitis was uncomplicated in 194 (68.3%) and complicated in 90 (31.7%). Age, symptom duration, neutrophil percentage, CRP and hospital stay were higher in the complicated AA group (P < .05). The mean differences between uncomplicated and complicated AA were: age 13.2 years (95% CI: 8.2-18.2), symptom duration 14.1hours (95% CI: 6.3-21.9), neutrophil percentage 5.0% (95% CI: 3.2-6.8), CRP 73.6mg/l (95% CI: 50.0-97.2) and hospital stay 2.2 days (95% CI: 1.4-3.0), with p<0.05 for all these variables. A model based on the preoperative parameters (age, symptom duration, neutrophil percentage and CRP) was calculated to predict the likelihood of complicated AA. The receiver operating characteristic (ROC) of the model had an area under the curve of 0.80 (95% CI 0.75-0.85).

CONCLUSION

This model is able to diagnose complicated AA without the need for imaging techniques, although it must be validated with prospective analysis.

Global incidence of surgical site infection after appendectomy: a systematic review and meta-analysis

BACKGROUND

Although surgical site infection (SSI) is one of the most studied healthcare-associated infections, the global burden of SSI after appendectomy remains unknown.

OBJECTIVE

We estimated the incidence of SSI after appendectomy at global and regional levels.

DESIGN

Systematic review and meta-analysis.

PARTICIPANTS

Appendectomy patients.

DATA SOURCES

EMBASE, PubMed and Web of Science were searched, with no language restrictions, to identify observational studies and clinical trials published between 1 January 2000 and 30 December 2018 and reporting on the incidence of SSI after appendectomy. A random-effect model meta-analysis served to obtain the pooled incidence of SSI after appendectomy.

RESULTS

In total, 226 studies (729 434 participants from 49 countries) were included in the meta-analysis. With regard to methodological quality, 59 (26.1%) studies had low risk of bias, 147 (65.0%) had moderate risk of bias and 20 (8.8%) had high risk of bias. We found an overall incidence of SSI of 7.0 per 100 appendectomies (95% prediction interval: 1.0-17.6), varying from 0 to 37.4 per 100 appendectomies. A subgroup analysis to identify sources of heterogeneity showed that the incidence varied from 5.8 in Europe to 12.6 per 100 appendectomies in Africa (p<0.0001). The incidence of SSI after appendectomy increased when the level of income decreased, from 6.2 in high-income countries to 11.1 per 100 appendectomies in low-income countries (p=0.015). Open appendectomy (11.0 per 100 surgical procedures) was found to have a higher incidence of SSI compared with laparoscopy (4.6 per 100 appendectomies) (p=0.0002).

CONCLUSION

This study suggests a high burden of SSI after appendectomy in some regions (especially Africa) and in low-income countries. Strategies are needed to implement and disseminate the WHO guidelines to decrease the burden of SSI after appendectomy in these regions.

PROSPERO REGISTRATION NUMBER

CRD42017075257.

Population-based cohort study on the epidemiology of acute appendicitis in children in Sweden in 1987-2013

Background

The long‐term incidence of acute appendicitis has been reported to be declining in Europe and North America. Recent reports, however, indicate stabilized or even increased rates. The aim of this study was to investigate the present epidemiology of acute appendicitis and appendicectomy in a population‐based cohort of Swedish children.

Methods

The Swedish National Patient Register was queried for all children with acute appendicitis and/or appendicectomy in 1987–2013. Population‐based incidence rates were calculated. Rates were age‐ and sex‐adjusted, and analysed for temporal and regional trends.

Results

Some 56 774 children with acute appendicitis were identified, of whom 53 478 (94·2 per cent) underwent appendicectomy. The incidence rate of acute appendicitis declined by 43·7 per cent over 26 years, from 177·7 to 100·1 per 100 000 person‐years between 1987 and 2013. The most significant reduction was for non‐perforated appendicitis, from 138·5 to 68·4 per 100 000 person‐years between 1987 and 2009. The incidence rate of perforated appendicitis decreased from 28·0 to 19·9 per 100 000 person‐years and negative appendicectomies reduced from 48·5 to 3·6 per 100 000 person‐years during the study interval.

Conclusion

The incidence rates of acute appendicitis and negative appendicectomy have reduced markedly in Swedish children over time, with significantly different trends amongst non‐perforated appendicitis and perforated appendicitis. The full explanation for the observed findings is unclear.

Mean platelet volume and red cell distribution width as a diagnostic marker in acute appendicitis

Background:

Acute appendicitis (AA) is one of the most common causes of emergent surgeries. Many methods are used for its diagnosis.

Objectives:

This study was conducted to investigate the diagnostic value of MPV and RDW in acute appendicitis.

Patients and Methods:

This study was a retrospective multi-center cross sectional planned study. The study included 260 patients operated for AA and 158 patients as the control group. Groups were compared in terms of MPV, RDW, white blood cell count (WBC), neutrophil predominance (NP) and platelet count (PC).

Results:

MPV was significantly lower in AA group, compared to the control group (P < 0.001). The best cut-off level for MVP in AA was ≤ 7.3 fL and the sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and overall accuracy ratio were 45%, 89.2%, 87.3%, 49.6% and 61.7%, respectively. There was no significant difference between the two groups in terms of RDW and platelet values.

Conclusions:

MPV is a routinely measured parameter in complete blood count (CBC) and requires no additional cost. It significantly decreased in AA, having a greater sensitivity and NPV when combined with WBC and NP.

Outpatient antibiotic use and the incidence of acute appendicitis in Finland: a nationwide study from 1990-2008

BACKGROUND

The incidence of acute appendicitis (AA) has decreased in Finland. We hypothesized that changing trends in outpatient antibiotic use might explain at least part of this declining incidence of AA.

METHODS

The number of all patients with AA in Finland was extracted from the national data base from 1990 to 2008. For comparison, the incidence of acute diverticulitis of the colon (AD) was also recorded. All outpatient prescriptions of antibiotics belonging to the major groups of these drugs were also recorded. We used unit root and co-integration analyses for statistical analysis of the data in the study.

RESULTS

The incidence of AA in Finland declined from 14.5 to 9.8 per 10,000 inhabitants (32%) and the incidence of AD increased by 47% between 1993 and 2007. The total outpatient use of antibiotics did not increase during this same period, but the use of antibiotics effective widely against colonic pathogens (macrolides, fluoroquinolones, and cephalosporins) increased significantly. No correlation was found between the incidence of AA, that of AD, and the use of different groups of antibiotics.

CONCLUSIONS

Our nationwide registry study indicated that changes in outpatient antibiotic use do not explain the decreasing trend in AA in Finland. Other factors, such as improved diagnosis of AA, may have some role in the decreasing incidence of AA.

Single institution's experience in laparoscopic appendectomy as a suitable therapy for complicated appendicitis

PURPOSE

Although laparoscopic appendectomy (LA) for acute appendicitis (AA) is widely performed, the value of LA for the treatment of complicated appendicitis (CA) is still controversially discussed.

METHODS

In a retrospective study, we analyzed the clinical records of 404 patients who underwent LA or conversion (intention-to-treat group) or open appendectomy (OA) for AA or CA at the Alfried Krupp Hospital Essen-Rüttenscheid, Germany between January 2007 and December 2010.

RESULTS

AA was treated in 64.2 % by LA and in 35.8 % by OA; the LA-to-OA conversion rate amounts to 3.7 %. CA was treated in 56 % by LA and in 44 % by OA. The LA-to-OA conversion rate here is 13.1 %, and compared to AA, it is significantly (P < 0.01) higher. Comparing LA with OA in both patient groups, we find no significant difference in the overall complication rate, the rate of postoperative intraabdominal abscesses and postoperative ileus. However, in both patient groups, the wound infection rate was significantly lower in patients who had undergone LA (AA P < 0.05 versus CA P < 0.01). In contrast to patients suffering from AA, patients with CA needed significantly less resurgery when treated by LA as compared to OA (P < 0.001). While the duration of surgery for the treatment of AA and CA was similar, the hospitalization time was significantly shorter with LA than with OA (AA P < 0.05 versus CA P < 0.001).

CONCLUSIONS

The data suggest that LA is advantageous not only in the treatment of AA, but also in the therapy of CA. Thus, LA may become a proper and safe routine method if performed by an experienced surgeon.

Clinical manifestations in children with ruptured appendicitis

OBJECTIVES

Appendicitis is the most common abdominal condition leading to urgent surgery in children. With the goal of identifying signs and symptoms that will allow prompt diagnosis of rupture of the appendix and thus decrease associated morbidities, our aim was to determine factors associated with ruptured appendicitis in children diagnosed with appendicitis.

METHODS

The medical records of children aged 17 years or younger with a postoperative diagnosis of acute appendicitis treated at Cathay General Hospital, Taipei, Taiwan, from January 2002 and May 2009, were retrospectively reviewed. The patients were divided into with and without ruptured appendicitis.

RESULTS

Of the 228 patients, 140 had a postoperative pathological diagnosis of a nonperforated appendix, and 88 had a diagnosis of perforated appendix, resulting in a perforation rate of 38.6%. Younger age, longer duration of abdominal pain, fever, muscle guarding, and elevated C-reactive protein level were significantly associated with a perforated appendix.

CONCLUSIONS

Younger age, longer duration of abdominal pain, fever, muscle guarding, and elevated C-reactive protein level are significantly associated with a perforated appendix; these factors should be closely considered in the evaluation of individuals with suspected appendicitis.

The process of treating pediatric appendicitis

BACKGROUND

A large service and distant geographical area can make the process of diagnosing and treating appendicitis a challenge.

METHODS

Hospital records of children treated for appendicitis between 2007 and 2009 were retrospectively analyzed, including time from emergency (ER) to operating room (OR), diagnostic imaging (DI) utilization, preoperative antibiotic usage, operating time, length of stay (LOS), and perforation rate.

RESULTS

The perforation rate was 34%, with longer LOS. Transfer time to the children's hospital between ER inside and outside the city was not different. ER to OR time was significantly shorter for patients assessed at the children's hospital directly. Ultrasound remained the most used DI modality (55%). Preoperative antibiotics were only fully administered in 42% of the cases.

CONCLUSION

A clinical pathway for pediatric appendicitis may address the challenges of the process of pre-ER, ER to OR, and OR care to maintain an acceptable perforation rate.

Changing incidence of acute appendicitis and nonspecific abdominal pain between 1987 and 2007 in Finland

BACKGROUND

The incidence of acute appendicitis has declined in many countries. The aim of this study was to determine the trends in incidence of acute appendicitis (AA), appendectomies for AA, and nonspecific abdominal pain (NSAP) in Finland between 1987 and 2007.

METHODS

We carried out a national register study. Demographic features were investigated. Diagnoses and procedures were classified according to the World Health Organization International Classification of Diseases. Data were analyzed for each of all five University Hospital districts (UHD) of Finland.

RESULTS

During the observation period of 21 years, 186,558 appendectomies were performed in Finland, of which 137,528 (74%) cases were reported as AA. The incidence of acute appendicitis declined 32%. The diagnostic accuracy improved from 73 to 82% and was higher in men. The accuracy rate among the male patients was stable throughout the two decades; among the female patients it rose from 63 to 75%. The incidence of appendicitis was highest in patients aged 15-24 years. The average incidence of NSAP was 34/10,000/year, and it was higher in older age groups. There was a large geographical disparity in the incidence of NSAP.

CONCLUSION

The incidence of acute appendicitis as well as the incidence of appendectomies is declining in Finland. The incidence of the NSAP has also been declining but we did not find any correlations between the incidences of the acute appendicitis and NSAP. There were clear geographical differences in the incidence of NSAP but not in the incidence of AA.

The epidemiology of appendicitis and appendectomy in South Korea: national registry data

Background

Appendicitis is one of the most frequent acute surgical conditions of the abdomen, and appendectomy is one of the most commonly performed operations in the world. However, epidemiological data on appendicitis have not been reported for South Korean or East Asian populations.

Methods

We analyzed the epidemiological features and lifetime risk of appendicitis and appendectomy in South Korea using data collected for the national health insurance database from 2005 through 2007.

Results

Appendectomy was performed in 59.70% of inpatients diagnosed with appendicitis. The overall incidences of appendicitis, total appendectomy, and perforated appendectomy were 22.71, 13.56, and 2.91 per 10 000 population per year, respectively. The incidence of appendicitis and appendectomy showed clear seasonality, with a peak in summer. The standardized lifetime risks of appendicitis and appendectomy were constant from 2005 through 2007. A life table model suggests that the lifetime risk of appendicitis is 16.33% for males and 16.34% for females, and that the lifetime risk of appendectomy is 9.89% for males and 9.61% for females.

Conclusions

As compared to results obtained in research on Western populations, appendicitis and appendectomy had a similar perforation rate and seasonality, but a higher overall incidence, in South Koreans. Between 2005 and 2007, the incidence of appendicitis and appendectomy was constant. Overall, an estimated 15 incidental appendectomies are performed to prevent 1 inpatient with suspected appendicitis, and 26 incidental appendectomies are performed to prevent 1 appendectomy. Incidental appendectomy may have greater preventive value in Koreans.

Pediatric appendicitis rupture rate: disparities despite universal health care

BACKGROUND/PURPOSE

Significant socioeconomic disparities have been observed in the rates of perforated appendicitis among children in private health care. We seek to explore if, in the Canadian system of public, universal health care access, pediatric appendicitis rupture rates are an indicator of health disparities.

METHODS

Using the Population Health Research Data Repository housed at Manitoba Centre for Health Policy, a retrospective analysis over a 20-year period (1983-2003) examined all patients aged less than 18 years with International Classification of Diseases, Ninth Revision, Clinical Modification diagnostic and procedural codes for appendicitis (N = 7475). Multivariate logistic regression analysis was used to calculate odds ratios in the association between appendiceal rupture rates and the patient's socioeconomic status (SES) based upon average household income of the census area adjusted for age, sex, area of residence, and treating hospital.

RESULTS

The overall appendiceal rupture rate was 28.8%. Significant positive predictors of appendiceal rupture were lower rural SES, lower urban SES, younger age, northern area of residence, and receiving treatment at the province's only pediatric tertiary care hospital.

CONCLUSION

Despite free, universal access health care, children from lower SES areas have increased appendiceal rupture rates. Seeking and accessing medical attention can be complicated by social, behavioral, and geographical problems.

Dramatic decline of acute appendicitis in Greece over 30 years: index of improvement of socioeconomic conditions or diagnostic aids?

BACKGROUND AND AIMS

There are several reports showing a continuing fall in the incidence of acute appendicitis in the western countries. Our aim was to study the trend of the incidence of acute appendicitis in the Greek population over 30 years.

METHODS

We analyzed the data referring to the years 1970-1999 on the incidence and mortality of acute appendicitis for the entire Greek population. Data were retrieved from the Annual Bulletin for the Social Welfare and Health Statistics of the National Statistics Service of Greece. In this database, acute appendicitis was a hospital discharge diagnosis.

RESULTS

Over the study period, there was a 75% decrease of the age-standardized incidence of acute appendicitis from 652/100,000 to 164/100,000. The median female-to-male ratio of hospitalized patients for appendicitis of the study period (1970-1999) fell progressively from 1.27 in the year 1970 to 0.93 in the year 1999. The case fatality rates remained constant, ranging below 0.09 deaths per 100 appendicitis cases.

CONCLUSION

There is a significant decline of the incidence of acute appendicitis in the Greek population over the years 1970-1999. This time trend is probably related to the improvement of the socioeconomic conditions over the same period and not to the introduction of new diagnostic aids.

Review of the pathological results of 2660 appendicectomy specimens

PURPOSE

Appendicitis is the most commonly performed emergency abdominal surgery. The appendix can also be the site of a variety of neoplasms and unusual inflammatory conditions. A retrospective review was performed to determine the pathological diagnoses in appendicectomy specimens.

METHODS

This study is a retrospective analysis of 2660 appendicectomies performed from 1997 to 2003. The reports were analyzed for the following parameters: age-related incidence of acute appendicitis, seasonal variation in presentation, perforation rate, rate of negative and incidental appendicectomy, and the incidence of other pathologies encountered.

RESULTS

Of the 2660 appendicectomy specimens, acute appendicitis was seen in 1718 patients (64.58%), with a peak in patients in their second decade (35.09% of cases of acute appendicitis). The perforation rate was 13.9% and was significantly higher in patients aged 70 years or more (P < 0.001). The negative appendicectomy rate was 28.8%, and was significantly higher in female patients (P < 0.001) and in the 11-30 year age group (P < 0.001). Other pathologies include carcinoid (0.52%), adenocarcinoma (0.39%), and mucinous cystadenoma (0.60%).

CONCLUSIONS

The high rate of negative appendicectomy among female patients and the increased incidence of perforation in elderly patients reinforce the validity of the judicious use of laparoscopy in these populations. There are still a number of unusual histologies found in appendicectomy specimens supporting the continued use of routine histology.

Familial Mediterranean fever (FMF) in Turkey: results of a nationwide multicenter study

Familial Mediterranean fever (FMF) is an autosomal recessive disease that is prevalent among eastern Mediterranean populations, mainly non-Ashkenazi Jews, Armenians, Turks, and Arabs. Since a large proportion of all the FMF patients in the world live in Turkey, the Turkish FMF Study Group (FMF-TR) was founded to develop a patient registry database and analyze demographic, clinical, and genetic features. The cohort was composed of 2838 patients (mean age, 23.0 +/- 13.33 yr; range, 2-87 yr), with a male:female ratio of 1.2:1. There was a mean period of 6.9 +/- 7.65 years from disease onset to diagnosis; the period was about 2 years shorter for each decade since 1981. Ninety-four percent of patients were living in the central-western parts of the country; however, their familial origins (70% from the central-eastern and Black Sea regions) reflected not only the ongoing east to west migration, but also the historical roots of FMF in Turkey. Patients' clinical features included peritonitis (93.7%), fever (92.5%), arthritis (47.4%), pleuritis (31.2%), myalgia (39.6%), and erysipelas-like erythema (20.9%). Arthritis, arthralgia, myalgia, and erysipelas-like erythema were significantly more frequent (p < 0.001) among patients with disease onset before the age of 18 years. Genetic analysis of 1090 patients revealed that M694V was the most frequent mutation (51.4%), followed by M680I (14.4%) and V726A (8.6%). Patients with the M694V/M694V genotype were found to have an earlier age of onset and higher frequencies of arthritis and arthralgia compared with the other groups (both p < 0.001). In contrast to other reported studies, there was no correlation between amyloidosis and M694V homozygosity in this cohort. However, amyloidosis was still remarkably frequent in our patients (12.9%), and it was prevalent (27.8%) even among the 18 patients with a disease onset after age 40 years. Twenty-two patients (0.8%) had nonamyloid glomerular diseases. The high prevalence of vasculitides (0.9% for polyarteritis nodosa and 2.7% for Henoch-Schonlein purpura) and high frequency of pericarditis (1.4%) were striking findings in the cohort. Phenotype II cases (those patients with amyloidosis as the presenting or only manifestation of disease) were rare (0.3% or less). There was a high rate of a past diagnosis of acute rheumatic fever, which suggested a possible misdiagnosis in children with FMF presenting with recurrent arthritis. To our knowledge, this is the largest series of patients with FMF reported from 1 country. We describe the features of the disease in the Turkish population and show that amyloidosis is still a substantial problem.

Role of appendicitis and appendectomy in the pathogenesis of ulcerative colitis: a critical review

Besides a genetic predisposition, a causal role of various environmental factors has been considered in the etiology of ulcerative colitis (UC). The association between appendectomy and UC has recently been the subject of intense scrutiny in the hope that it may lead to the identification of important pathogenetic mechanisms. Published data from animal models of colitis demonstrated reduction in experimental colitis after appendectomy, especially if performed at an early age. Several epidemiological case control and cohort studies have shown a strong and consistent relationship. The metaanalysis of 17 case-controlled studies showed an overall odds ratio 0.312 (95% confidence intervals = 0.261-0.373) in favor of appendectomy (p < 0.0001). One of the two recent large cohort studies is in agreement with these results, but the other failed to confirm them. All these studies have suggested that alterations in mucosal immune responses leading to appendicitis or resulting from appendectomy may negatively affect the pathogenetic mechanisms of UC. Further investigation of the role of appendectomy in UC is expected to open new fields for basic scientific research and may lead to the improvement of our understanding for the disease pathogenesis.