The comparison of the effectiveness of tomography and Alvarado scoring system in patients who underwent surgery with the diagnosis of appendicitis

Abstract

Objective: The aim of this study is to compare the effectiveness of computed tomography and Alvarado scoring system in the diagnosis of acute appendicitis in patients who underwent appendectomy with the preliminary diagnosis of acute appendicitis.
Material and Methods: One hundred and one patients who underwent appendectomy with the diagnosis of acute appendicitis between January and December 2011 were included in the study. Alvarado scores were calculated, and abdominal tomography scans were obtained for each patient before surgery. Patients with Alvarado score ≥7 were considered to have appendicitis while patients with a score <7 were considered not to have appendicitis. Patients were classified into two groups based on the presence of appendicitis findings on abdominal tomography. Histopathological examination of the appendices was performed following appendectomy. All patients were classified into groups according to pathology results, Alvarado score and tomography findings. The effectiveness of Alvarado score and tomography were compared using the McNemar test.
Results: Sixty patients (59.4%) were male and 41 (40.6%) were female, with a mean age of 32 years (5-85 years). The rate of negative appendectomy was 3.9%. In 78 patients (77.3%) the Alvarado score was ≥7, while 23 patients (22.7%) had Alvarado scores <7. The presence of appendicitis was determined by histopathology in 22 out of 23 patients whose Alvarado score was <7. Tomography indicated appendicitis in 97 patients (95.9%) whereas four patients (4.1%) exhibited no signs of appendicitis by tomography. However, histopathological evaluation indicated the presence of appendicitis in those four patients as well.
Conclusion: The study results imply that tomography is a more effective means of diagnosing acute appendicitis as compared to the Alvarado scoring system.

Keywords: Appendicitis, Alvarado score, tomography

Introduction

Acute appendicitis (AA) is one of the most common causes of surgical abdominal pain. It can be confused with other diseases due to atypical complaints or variations in complaints by age and sex. If appendicitis cannot be correctly diagnosed, then either an unnecessary appendectomy is performed or complications such as perforation develop due to delay in diagnosis. Therefore, timely diagnosis of AA is imperative.
The Alvarado scoring system is a practical evaluation method used to diagnose acute appendicitis by scoring patient’s complaints and symptoms. It was first proposed in 1986 by Alvarado (1). Alvarado score of 1-4 points is considered as no risk of appendicitis, patients with a score of 5-6 require either observation or additional work-up, while patients with a score higher than 7 are considered as AA (2-5). The data used for Alvarado scoring are shown in Table 1. Acute appendicitis can be correctly diagnosed in 70% of patients by using Alvarado scoring alone (6). Despite Alvarado scoring, imaging methods such as ultrasound (US) and computed tomography (CT) are utilized to avoid an unnecessary appendectomy and diagnose AA before perforation.

Table 1. Alvarado score components

Material and Methods

This study was planned prospectively. One hundred-one patients who underwent surgery for acute appendicitis between January-December 2011 and underwent an abdominal CT were enrolled in the study. Fatih University Faculty of Medicine Hospital Ethics Committee approved the study. Patients who did not undergo surgery, and those who were diagnosed with appendicitis without a CT were excluded.
The complaints of patients along with physical examination and laboratory results were recorded. Alvarado score was calculated based on values presented in Table 1. All study patients were scanned with multi-slice CT for abdominal imaging. An appendiceal lumen larger than 7 mm, presence of an appendicolith, fluid accumulation in the appendix region, presence of inflammation at the meso-appendix were considered as significant signs of AA on CT. All patients were operated with the presumptive diagnosis of AA. Four patients were operated due to clinical suspicion although there were no signs of appendicitis on CT. Other findings and pathologies beside appendicitis were also recorded. The appendix was examined histopathologically after surgery.
All patients were divided into groups after histopathologic examination according to their Alvarado score and CT findings (Table 2).

Table 2. Patient distribution according to pathology, tomography and Alvarado results

Table 3. Correlation of Alvarado score and tomography results according to McNemar test

Results

The study enrolled 101 patients. 60 patients (59.4%) were male and 41 (40.6%) were female, with a mean age of 32 years (5-85). Four patients who underwent surgery with a preliminary diagnosis of AA and had an appendectomy did not have histological appendicitis. Two of these patients had epiploic appendicitis and the other two patients had normal appendix vermiformis. Based on this, our negative appendectomy rate was determined as 3.9% (4/101).
Appendicitis was detected in 97 patients according to histopathology results. The Alvarado score of 75 of the 97 patients (77.3%) with appendicitis was ≥7, and was <7 in 22 (22.7%). In 93 of these 97 patients (95.9%), appendicitis findings were observed on CT, while 4 patients (4.1%) showed no signs of appendicitis. Within the four patients without appendicitis on histopathologic diagnosis, three had an Alvarado score ≥7 and one <7. However, all four patients had appendicitis findings on CT (Table 2).
In patients with histopathologically proven appendicitis, there was a statistically significant discordance among patients with Alvarado score ≥7 and those with appendicitis findings on CT (p<0.01).
In our study, the positive predictive value of Alvarado score in the diagnosis of AA was determined as negative predictive value (PPV) = 0.9615, the negative predictive value (NPV) = 0.043, sensitivity as 0.7732, and specificity as 0.25. These values could not be calculated for tomography since there was no patient in whom the appendix could not be visualized or the appendix could not be detected on pathology.
For patients with no signs of appendicitis on histopathology, there was no significant difference in terms of diagnosis failure between patients with an Alvarado score ≥7 and those with appendicitis findings on CT (p<0.05).

Discussion

Acute appendicitis can often be diagnosed by a simple examination and laboratory tests, but confirming the diagnosis can be difficult if the signs and symptoms are atypical. Studies (11, 12) report the negative appendectomy rate as 16.5-22.8%, and perforated appendectomy rate as 15-23%. Thus, the timely and accurate diagnosis of AA is important. In our study, a negative appendectomy was performed in four patients and our rate of negative appendectomy was determined as 3.9% (4/101). This low rate can be attributed to the inclusion criteria of the study that enrolled only patients with CT, but it is also an indicator of the effectiveness of CT in the diagnosis of appendicitis.
Alvarado scoring is a method to assess the risk of AA in a particular patient. In a study by Inan et al (6), the sensitivity of the Alvarado score was reported as 70.4% and specificity as 71.4%, while Jalil et al. (13) reported these rates as 66% and 81%, respectively. In our study, 75 out of 78 patients with an Alvarado score ≥7 (96.1%) were pathologically identified to have appendicitis. Appendicitis was pathologically detected in 22 out of 23 patients with an Alvarado score <7 (95.6%). According to these results, an Alvarado score of ≥7 is quite an effective method for the diagnosis of AA, but a score <7 is not a reliable method to rule out appendicitis.
Despite implementation of the Alvarado scoring system that was based on clinical and laboratory results, negative appendectomy and perforated appendicitis have been reported. In a study using only the Alvarado score (14), the negative appendectomy rate was reported as 15.6% and the perforated appendectomy rate as 7.8%. The more frequent occurrence of atypical clinical symptoms especially in women, in children and the elderly makes it difficult to correctly diagnose AA. Imaging techniques are required more in such circumstances (11). Ultrasonography and CT are reported to decrease the negative appendectomy rate especially in women (15). As its availability, faster imaging opportunity, and diagnostic accuracy rate increased CT has been used more frequently in the diagnosis of AA.
Ultrasound has some advantages in the diagnosis of AA. It is a quick, cheap, and more available method with no radiation risk, but its success depends on the experience of the physician. In a meta-analysis, the sensitivity of sonography in the diagnosis of appendicitis was reported as 86% and the specificity as 81% (16), with different results reported in the literature. The false negative rate of US in the diagnosis of AA was determined as 14.7% in a study (6) stating that it should not be used as a stand-alone diagnostic test.
Computed tomography is superior to other imaging modalities in the diagnosis of appendicitis. It was found to be successful particularly in ruling out AA (17). The negative appendectomy rate declined after the introduction of computerized tomography (16, 18). The sensitivity of CT was reported as 86% (19), and the specificity as 66%. The sensitivity and specificity of CT in patients with an Alvarado score higher than 7 is 90.4% and 95%, respectively (3). In a meta-analysis (8), the negative appendectomy rate with only clinical evaluation was 16.7%, while this rate decreased to 8.7% in patients with CT.
In our study, appendicitis findings were observed on CT in 97 patients (95.9%), in 93 of these patients (95.8%) the pathologic diagnosis was appendicitis, while appendicitis was not detected in 4 (4.1%) patients by pathologic evaluation. Two of these patients had inflammation of the epiploic appendix that was mistaken for acute appendicitis on CT. The other two patients are those without appendicitis findings on CT but were determined to have AA based on histopathologic findings.
In all other 4 patients without signs of appendicitis on CT, appendicitis was identified pathologically. According to these results, CT is an effective method for diagnosing appendicitis. However, patients with clinical suspicion of appendicitis in whom CT findings of appendicitis are not detected should be evaluated cautiously.
In our study, the number of patients accepted as having AA according to the Alvarado score was 78 (77.2%). If the diagnosis was made only with the Alvarado score, 3 patients with a score of 1-4 would not be diagnosed as AA, and 20 patients with a score of 5-6 score would require further investigations with imaging methods or observation. But the number of patients who were diagnosed with AA by CT was 97 (95.9%). Following CT scan, patients were diagnosed without any further evaluation and were directly operated. Accordingly, we observed the significant superiority of CT in comparison to the Alvarado score in the diagnosis of AA.
If we evaluate error in AA diagnosis, three patients with an Alvarado score of 1-4 were histologically diagnosed with AA. But in CT, only four (4.1%) patients did not show any signs of appendicitis. According to these results, the failure rate of both methods in discriminating patients without AA were found to be similar.
As known, the Alvarado score that is based on clinical evaluation and laboratory measurements and CT are not alternatives to each other. In almost all patients, the values that the Alvarado score is based on are already being evaluated. However, because CT is now an easily accessible imaging method, with a shorter imaging time, and a fair cost with high diagnostic accuracy rate in AA, it is an analysis method that is being preferred quite more.
Our study was limited to “patients who were operated with the diagnosis of appendicitis”, and not “all patients with suspected appendicitis” were included. So, there are some limitations of our study. Data on patients who had CT for suspicion of AA, patients who were operated with the diagnosis of appendicitis without CT, and of patients who were followed-up with suspicion of appendicitis but did not undergo surgery were not included in the study. Comparison of the Alvarado score and CT findings in all patients with suspected AA may yield different results, and more reliable conclusions could be made regarding the diagnostic power of these two methods in appendicitis.

Conclusion

According to the results of this study, CT is more effective in the diagnosis of AA than the Alvarado score. Therefore, in addition to classic clinical evaluation and laboratory data, CT can reduce the rate of negative laparotomy or laparoscopy in patients with suspected appendicitis by providing more accurate and faster diagnosis of AA.

Ethics committee approval was received for this study from the ethics committee of Fatih University School of Medicine.

Additional informed consent was not taken because the diagnosis process and the intervention were routine for appendicitis.

Externally peer-reviewed.

Concept - A.Ö., Z.Y.; Design - A.Ö.; Supervision - Ö.F.A., A.Ö.; Funding - A.Ö., Z.Y.; Materials - A.Ö., T.A.; Data Collection and/or Processing - Z.Y., T.A.; Analysis and/or Interpretation - A.Ö., Ö.F.A.; Literature Review - T.A.; Writer - A.Ö., Z.Y.; Critical Review - Ö.F.A., A.Ö.

No conflict of interest was declared by the authors.

The authors declared that this study has received no financial support.

We would like to thank Dr. Fatma Fidan and Doç. Dr. Levent Sarı for his help with the statistical analyses of our data.

References

1. Alvarado A. A practical score for the early diagnosis of acute appendicitis. Ann Emerg Med 1986; 15: 557-564.
2. Pouget-Baudry Y, Mucci S, Eyssartier E, Guesdon-Portes A, Lada P, Casa C, et al. The use of the Alvarado score in the management of right lower quadrant abdominal pain in the adult. J Visc Surg 2010; 147: e40-44.
3. McKay R, Shepherd J. The use of the clinical scoring system by Alvarado in the decision to perform computed tomography for acute appendicitis in the ED. Am J Emerg Med 2007; 25: 489-493.
4. Sun JS, Noh HW, Min YG, Lee JH, Kim JK, Park KJ, et al. Receiver operating characteristic analysis of the diagnostic performance of a computed tomographic examination and the Alvarado score for diagnosing acute appendicitis: emphasis on age and sex of the patients. J Comput Assist Tomogr 2008; 32: 386-391.
5. Cağlayan K, Günerhan Y, Koç A, Uzun MA, Altınlı E, Köksal N. The role of computerized tomography in the diagnosis of acute appendicitis in patients with negative ultrasonography findings and a low Alvarado score. Ulus Travma Acil Cerrahi Derg 2010; 16: 445-448.
6. İnan M, Tulay SH, Besim H, Karakaya J. The value of ultrasonography and its comparison with Alvarado scoring system in acute appendicitis. Ulus Cerrahi Derg 2011; 27: 149-153.
7. Leite PN, Pereira JM, Cunha R, Pinto P, Sirlin C. Computed tomography evaluation of appendicitis and its complications: Imaging techniques and key diagnostic findings. Am J Roentgenol 2005; 185: 406-417.
8. Ohle R, O’Reilly F, O’Brien KK, Fahey T, Dimitrov BD. The Alvarado score for predicting acute appendicitis: A systematic review. BMC Med 2011; 9: 139.
9. Shrivastava UK, Gupta A, Sharma D. Evaluation of the Alvarado score in the diagnosis of acute appendicitis. Trop Gastroenterol 2004; 25: 184-186.
10. Menteş O, Eryılmaz M, Harlak A, Oztürk E, Tufan T. The value of serum fibrinogen level in the diagnosis of acute appendicitis. Ulus Travma Acil Cerrahi Derg 2012; 18: 384-388.
11. Scammell S, Lansdale N, Sprigg A, Campbell D, Marven S. Ultrasonography aids decision-making in children with abdominal pain. Ann R Coll Surg Engl 2011; 93: 405-409.
12. Yilmaz M, Akbulut S, Kutluturk K, Sahin N, Arabaci E, Ara C, et al. Unusual histopathological findings in appendectomy specimens from patients with suspected acute appendicitis. World J Gastroenterol 2013; 19: 4015-4022.
13. Jalil A, Shah SA, Saaiq M, Zubair M, Riaz U, Habib Y. Alvarado scoring system in prediction of acute appendicitis. J Coll Physicians Surg Pak 2011; 21: 753-755.
14. Khan I, ur Rehman A. Application of Alvarado scoring system in diagnosis of acute appendicitis. J Ayub Med Coll Abbottabad 2005; 17: 41-44.
15. Bendeck SE, Nino-Murcia M, Berry GJ, Jeffrey RB Jr. Imaging for suspected appendicitis: negative appendectomy and perforation rates. Radiology 2002; 225: 131-136.
16. Terasawa T, Blackmore CC, Bent S, Kohlwes RJ. Systematic review: computed tomography and ultrasonography to detect acute appendicitis in adults and adolescents. Ann Intern Med 2004; 141: 537-546.
17. Johansson EP, Rydh A, Riklund KA. Ultrasound, computed tomography, and laboratory findings in the diagnosis of appendicitis. Acta Radiol 2007; 48: 267-273.
18. Krajewski S, Brown J, Phang PT, Raval M, Brown CJ. Impact of computed tomography of the abdomen on clinical outcomes in patients with acute right lower quadrant pain: a meta-analysis. Can J Surg 2011; 54: 43-53.
19. Yildirim E, Karagülle E, Kirbaş I, Türk E, Hasdoğan B, Tekşam M, et al. Alvarado scores and pain onset in relation to multislice CT findings in acute appendicitis. Diagn Interv Radiol 2008; 14: 14-18.