|Year : 2010 | Volume
| Issue : 2 | Page : 58-65
Acute perforated appendicitis: An analysis of risk factors to guide surgical decision making
Savio G Barreto1, Edward Travers1, Tudor Thomas1, Clare Mackillop1, Leong Tiong1, Michelle Lorimer2, Randall Williams2
1 Department of Surgery, Modbury Hospital, South Australia, Australia
2 Data Management and Analysis Centre, The University of Adelaide, South Australia, Australia
|Date of Web Publication||28-Mar-2012|
Head - Department of Surgery, Modbury Hospital, South Australia - 5092
Introduction: Acute perforated appendicitis is associated with increased post-operative morbidity and mortality. Avoiding delays in surgery in these patients may play a role in reducing observed morbidity. Objective: To analyze the clinico-pathological profile and outcomes in a cohort of patients undergoing emergency appendicectomies for suspected acute appendicitis and to determine factors influencing the risk of perforated appendicitis in order to aid better identification of such patients and develop protocols for improved management of this subset of patients. Materials and Methods: A retrospective analysis of patients undergoing emergency appendicectomies following presentation with acute appendicitis to the Modbury hospital, South Australia from March 2007 to April 2011 was conducted. Statistical analyses were performed in SAS 9.2. Results and Discussion: 506 patients underwent emergency appendectomy for acute appendicitis which included equal number of male and female patients with a median age of 25 years. Perforated appendicitis was found in 102 (20%) patients. Post-operative morbidity was significantly higher in patients with perforated appendicitis (28.4% vs 4.7%; P<0.0001). Male sex, patients older than 60 years, along with raised neutrophil counts and C-reactive protein levels were found to be significantly associated with the risk of perforation (P<0.05). Conclusions: Acute perforated appendicitis is associated with high morbidity. The increased risk of perforation in males and elderly patients appears unrelated to delays in presentation, diagnosis, or surgery. Patients with clinically diagnosed acute appendicitis and an elevation in neutrophil count and CRP level must be considered candidates for early surgery as they are likely to have an appendicular perforation.
Keywords: Carcinoids, male, tumors
|How to cite this article:|
Barreto SG, Travers E, Thomas T, Mackillop C, Tiong L, Lorimer M, Williams R. Acute perforated appendicitis: An analysis of risk factors to guide surgical decision making. Indian J Med Sci 2010;64:58-65
|How to cite this URL:|
Barreto SG, Travers E, Thomas T, Mackillop C, Tiong L, Lorimer M, Williams R. Acute perforated appendicitis: An analysis of risk factors to guide surgical decision making. Indian J Med Sci [serial online] 2010 [cited 2013 May 22];64:58-65. Available from: http://www.indianjmedsci.org/text.asp?2010/64/2/58/94401
| ¤ Introduction|| |
The incidence of complicated acute appendicitis, including perforated or gangrenous appendicitis, remains considerably high (28-29%) , despite the availability of modern imaging and the use of laparoscopic surgery, sometimes even as a diagnostic tool for suspected appendicitis.  And while appendectomy for acute appendicitis is one of the most common intra-abdominal surgical procedures performed by general surgeons, , morbidity rates in the post-operative period remain between 9% and 18%. 
There has been an increasing trend to delay "uncomplicated" acute appendicitis cases that present after hours to be performed the next morning  in order to avoiding disrupting operating room schedules and to reduce the number of patients being operated on after hours on the premise that sleep deprivation and fatigue were associated with technical errors.  However, the importance of an urgent appendectomy cannot be understated especially because of the disparity in morbidity and mortality rates between perforated and non-perforated appendicitis.
The aim of the current study was
- to analyze the clinico-pathological profile and outcomes in a cohort of patients undergoing emergency appendectomies for suspected acute appendicitis, and
- to determine the factors influencing the risk of perforated appendicitis in order to aid better identification of such patients so as to develop protocols for improved management of this subset of patients.
| ¤ Materials and Methods|| |
A retrospective search of a prospectively maintained electronic database of the Modbury Hospital, a teaching hospital in South Australia, was undertaken. International Classification of Diseases (ICD) codes for acute appendicitis for a 50-month period, from March 2007 to April 2011 were analyzed with the aim of identifying all patients admitted to the hospital with acute appendicitis who underwent emergency appendectomies. This resulted in a total of 506 patients being identified. Each admission was reviewed within the electronic database for patient admission details.
Patients presenting with right lower abdominal pain, consistent examination findings, with supporting blood investigations, such as raised white cell and neutrophil counts and/or the inflammatory marker serum C-reactive protein (CRP) levels, were considered to have acute appendicitis and proceeded for an appendectomy (open, laparoscopic, and laparoscopic converted to laparotomy).
In patients in whom the diagnosis was unclear, the use of imaging (ultrasonography or computed tomography (CT) scan) was considered prior to planning surgery. The use of ultrasonography was preferred in children with an unclear diagnosis owing to the larger relative size of appendix rendering better visualization in them. Similarly, in young women, ultrasonography was preferred as the initial investigation in undifferentiated right lower abdominal pain. In the case of failure to conclusively rule out appendicitis, a diagnostic laparoscopy was preferred over the use of a CT scan. Antibiotics (usually a cephalosporin) were administered at induction of surgery.
Laparoscopic appendectomies were performed using the standard three port technique. In patients in whom the laparoscopic procedure could not be completed safely, an audit of surgical outcomes within the department found that a midline laparotomy was the most effective approach for completing the procedure-overriding the often unsuccessful use of the McBurney incision. Hence, it is the department policy that in patients in whom the appendectomy cannot be completed laparoscopically by a trained laparoscopic surgeon, the surgeon should then resort directly to a midline laparotomy. The choice of surgical approach (laparoscopy versus open) in pediatric patients was based on the actual size of the patient. In smaller patients, the open approach via the McBurney incision was preferred. Patients were labeled as having a perforated appendix based on the findings of a perforation at the time of surgery and confirmed on histopathology.
All appendectomy specimens were routinely submitted for histopathological analysis as per the hospital protocol.
Post-operative morbidity was defined as any complication (medical or surgical) encountered which prolonged the hospital stay of the patient and/or complications occurring with 30-days following surgery requiring re-admission.
Statistical analyses were performed in SAS 9.2. The probability of perforation was modeled using separate logistic regressions for each predictor. Then a multivariate logistic regression model was considered. All analyses were tested for significance at the 5% level. Unadjusted and adjusted odds ratios and 95% confidence intervals for each predictor are presented.
| ¤ Results|| |
506 patients underwent emergency appendectomies in the study period. These included 253 male (50%) and 253 female (50%) patients with a median age of 25 years (range = 4-90). The presenting complaint was right iliac fossa pain in all patients with median duration of symptoms of 2 days (range: 0-30).
418 patients (82%) underwent laparoscopic appendectomies while 53 patients (11%) had an open procedure. In 35 patients (7%), the procedure needed conversion from laparoscopy to a laparotomy. The median duration of stay was 2 days (range: 0-21).
Of the 506 patients, 455 patients (90%) had acute appendicitis confirmed on histology. Thirty-five patients (7%) had a histologically normal appendix while 16 patients had a pathology other then appendicitis (3%). [Table 1] provides the complete pathological profile of the histology. Hundred and two patients (20%) had a perforated appendix noted at the time of surgery.
|Table 1: Pathological profile of the 506 patients who underwent emergency appendectomy for suspected acute appendicitis|
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The overall post-operative morbidity rate was 9.4% (48 patients).). In patients with perforated appendicitis, the morbidity rate was 28.4% (29 out of 102 patients) which was significantly higher as compared to a rate of 4.7% (19 out of 404 patients) without perforation (P<0.0001). The spectrum of complications is listed in [Table 2].
Fourteen patients required re-surgery for complications. These included 11 patients with collections (pelvic or other), 1 suprapubic port exploration, 2 diagnostic laparoscopies for abdominal pain (1 patient had a stump hematoma found which was managed conservatively and the other patients had necrotic mesoappendicular fat necessitating excision of the fat).
Fifteen patients (3%) required re-admission.
Risk factors predicting perforated appendicitis
A comparison of the demographic factors, symptom duration, and blood investigations between the patients with a perforated and non-perforated appendicitis is provided in [Table 3].
|Table 3: Comparison of factors between patients with and without perforation|
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The results of the univariate analysis for factors associated with the likelihood of patients presenting with perforated appendicitis have been summarized in [Table 4]. Males (P<0.001) and patients older than 60 years (P<0.001) were found to be at a significantly increased risk of developing perforated appendicitis. Similarly, patients presenting after the second day of onset of their symptoms were found to be at a significantly increased risk with the risk increasing depending on whether they presented between 2 and 3 days of onset of symptoms or 4 and 9 days following the onset of symptoms. While the white cell count had no significance on the presence of perforated appendicitis on univariate analysis, the neutrophil count was found to have a significant effect on the probability of perforation (P<0.001) with the risk of perforation increasing by 10% for every unit increase in the neutrophil count above normal. Similarly, CRP levels were also found to have a significant effect on the probability of perforation (P<0.001) with the risk of perforation increasing by 1.4% for every unit increase in the CRP level. Patients in the pediatric age group were less likely to have a perforated appendicitis although this was not statistically different from the patients aged 15 to 59 years.
|Table 4: Results from logistic regression analysis for factors associated with the risk for perforated appendicitis|
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On multivariate analysis, when all the terms were included in the model of analysis, duration of symptoms was the only term which was no longer significant at the 5% level (P=0.35).
| ¤ Discussion|| |
The present study on emergency appendectomies for acute appendicitis conducted in a community teaching hospital in South Australia indicates that acute appendicitis is more common in the young population affecting males and females, alike. The findings of the study also indicate that the male sex and advanced age (>60 years) are demographic factors associated with an increased risk of perforation, while blood investigations at admission such as neutrophil count and CRP levels were independent predictors of risk of perforation. A combination of an elevated neutrophil count and CRP level taken together were also indicative of the risk of an underlying perforated appendix.
Perforated appendicitis was found to account for 20% of the cases in this study which is not dissimilar to the rates reported in other parts of the world. , The significantly increased morbidity rate following surgery for perforated appendicitis has been previously noted by Styrud et al.  and remains a concern.
The impact of age and sex on the risk of perforation has been previously reported.
Extremes of age and advancing age as well as the male sex have been previously demonstrated to be linked to a risk of perforation. ,,,, Delays in diagnosis, and hence in the surgical management, have been reported to be the likely causes. In the pediatric age group, their inability to clearly communicate symptoms, and in the elderly, confounding medical conditions and a decreased index of suspicion have been linked to delays in diagnosis.  However, our own data has failed to demonstrate an increased risk of perforation and its attendant morbidity in the pediatric age group. The department policy of avoiding delays in surgery once the diagnosis of acute appendicitis was made (as observed by the lack of difference in the median duration of symptoms to surgery in [Table 3]) could have accounted for the observed the lower perforation rate noted even in the pediatric age group. It, however, fails to explain the higher risk of perforations encountered in the elderly (>60 years) and amongst males. This indicates that there may be factors other than delays in presentation, diagnosis, or surgery, which influence the risk of perforation in these two groups. Males have been found to have a higher incidence of appendicular faecoliths and calculi  which are in turn associated with an increased risk of perforation. This could be one potential explanation for the increased risk of perforation in males. Advanced age and male sex have been found to be risk factors for perforation even in diverticular disease.  Changes in the colonic wall mechanical strength have been noted with advancing age.  These changes have been postulated to be linked to the increased risk of diverticular perforations noted in advancing age. While this has not been previously studied in appendicular tissue, we can only hypothesize that such changes may occur in the appendicular wall, as well, increasing the susceptibility to perforation with advancing age.
Blood investigations serve as an adjunct to clinical findings in the diagnosis of acute appendicitis.  The most commonly performed blood investigations in patients presenting with right lower quadrant pain are a complete blood count and CRP. Our data confirm the added use of neutrophil counts and CRP in predicting an appendicular perforation as a result of acute appendicitis. In the rapidly changing surgical scenario wherein patients with "uncomplicated" acute appendicitis, admitted after hours, are delayed to the next morning,  in a patient with clinical signs of acute appendicitis and the findings of an elevation in the blood parameters, namely neutrophil count and CRP (which are associated with an increased risk of perforation) such patients should be strongly considered as for an urgent appendectomy even if this entails performing the surgery after hours.
Our departmental policy of conversion directly from laparoscopy to a midline laparotomy in patients in whom the appendectomy cannot be completed laparoscopically by a trained laparoscopic surgeon has helped us avoid an unnecessary additional wound/scar caused by the use of the McBurney incision.
| ¤ Conclusions|| |
Acute perforated appendicitis is associated with a high morbidity. The increased risk of perforation in males and elderly patients appears to be unrelated to delays in presentation, diagnosis, or surgery. Patients with clinically diagnosed acute appendicitis and an elevation in two laboratory parameters, namely neutrophil count and CRP level must be considered candidates for early surgery as they are likely to have an appendicular perforation.
| ¤ Acknowledgements|| |
The authors wish to acknowledge Martin Moyse, Heather Hills and Emma Venning for their assistance in the data collection.
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[Table 1], [Table 2], [Table 3], [Table 4]