Diagnostic accuracy of computed tomography and ultrasound for the diagnosis of acute appendicitis: A systematic review and meta-analysis

INTRODUCTION

The diagnosis of acute appendicitis remains challenging. This review determined the current diagnostic accuracy of CT and ultrasound for suspected acute appendicitis in adults.

METHODS

This systematic review adhered to the PRISMA for diagnostic test accuracy guidelines. A systematic search was undertaken in appropriate databases. Screening of potential titles and abstracts, full-text retrieval, methodological quality assessment using QUADAS, and data extraction was performed. Meta-analyses were performed for relevant subgroups, and sensitivity analysis was completed to account for outliers. GRADE was utilized to assess the certainty of findings.

RESULTS

31 studies evaluating CT, 10 evaluating US, and six evaluating both were included. Pooled sensitivity and specificity for CT was 0.972 [0.958, 0.981] and 0.956 [0.941, 0.967] respectively, and 0.821 [0.738, 0.882] and 0.859 [0.727, 0.933] for US, respectively. When analyzing subgroups based on the use of contrast enhancement, sensitivity and specificity was highest for CT with intravenous and oral contrast (0.992 [0.965, 0.998], 0.974 [0.936, 0.99]), compared to CT with intravenous contrast (0.955 [0.922, 0.974], 0.942 [0.916, 0.960]). Low-Dose CT produced comparable values (0.934 [0.885,0.963], 0.937 [0.911, 0.955]) relative to these subgroups and standard dose non-contrast CT (0.877 [0.774,0.937], 0.914 [0.827, 0.959]). US studies which excluded equivocal findings demonstrated significantly greater values than the remainder of US studies (p < 0.0001).

CONCLUSION

The updated diagnostic test accuracies of CT, US and relevant subgroups should be implemented in light of factors such as dose, cost, and timing.

IMPLICATIONS FOR PRACTICE

For diagnosis of adult acute appendicitis: • CT with intravenous plus oral contrast enhancement yields statistically significantly greater diagnostic accuracy than CT with intravenous contrast alone. • Low-dose CT yields comparable sensitivity and specificity to standard-dose CT. • Ultrasound studies which exclude equivocal results may overinflate sensitivity and specificity.

Predictive factors and outcomes of negative appendectomy

BACKGROUND

The aim of this study was to assess predictive factors for negative appendectomy and to evaluate the outcomes of negative appendectomy.

METHODS

A retrospective chart review of 4,878 patients who underwent appendectomy at our institution from January 2008 to December 2014 was performed.

RESULTS

Younger age (≤15 years), normal white blood cell count, appendix diameter of less than 6 mm on computed tomography (CT), and CT grade less than 3 were found to be independent predictive factors for negative appendectomy. When complications were investigated according to the results of pathologic diagnosis, negative appendectomy had more complications than appendectomy for nonperforated appendicitis, and this was statistically significant.

CONCLUSIONS

When CT findings are equivocal, in deciding to operate for acute appendicitis, additional ultrasonography can be performed. Furthermore, if the patient is younger than 15 years and the white blood cell count is normal, it is recommended to monitor changes in symptoms a little longer rather than operating hastily.

Acute appendicitis in children: ultrasound and CT findings in negative appendectomy cases

BACKGROUND

To decrease the negative appendectomy rate in children, knowledge of the misleading imaging findings on US and CT in negative appendicitis cases is important.

OBJECTIVE

To evaluate the negative appendectomy rate and describe the imaging findings of US and CT that lead radiologists to misdiagnose acute appendicitis in children.

MATERIALS AND METHODS

From 2007 to 2013, 374 children operated for suspected appendicitis were proved to either have acute appendicitis (n = 348) or to be negative for appendicitis (n = 26) on pathological reports. Negative appendectomy rates were compared among imaging modalities, age groups and genders. We retrospectively reviewed US and CT findings from negative appendectomy cases.

RESULTS

The overall negative appendectomy rate was 7.0% (26/374). There were no statistically significant differences among the subgroups. The most common misleading presentations on US were sonographic tenderness (9/16, 56%) and non-compressibility (9/16, 56%). The most common misleading finding on CT were the presence of an appendicolith or hyperdense feces (5/12, 42%). Periappendiceal fat inflammation was observed in only one case of negative appendicitis on US and on CT.

CONCLUSION

Radiologists can misdiagnose children with equivocal diameters of appendices as having acute appendicitis when sonographic tenderness or non-compressibility is present on US and when an appendicolith or hyperdense feces is noted on CT. The possibility of negative appendicitis should be borne in mind when periappendiceal fat inflammation is absent or minimal in indeterminate cases.

CT of acute appendicitis: can diagnostic accuracy serve as a practical performance metric for readers specialized in abdominal imaging?

PURPOSE

To investigate diagnostic accuracy for acute appendicitis at computed tomography (CT) as a performance metric for radiologists specialized in abdominal imaging.

MATERIALS AND METHODS

We retrospectively identified six attending abdominal imagers who each independently interpreted over 100 CT studies for suspected acute appendicitis.

RESULTS

The mean number of studies per reader was 311 (range, 129-386). Mean reader diagnostic accuracy was 95.0% (range, 91.4-97.1%). Only one had a diagnostic accuracy (91.4%) that was significantly lower than all others.

CONCLUSION

Diagnostic accuracy for acute appendicitis at CT may be an impractical performance metric for radiologists specialized in abdominal imaging.

Appendicitis: what does really make the difference between private and public hospitals?

Background

Appendicitis is one of the most common surgical emergencies and is also a time-sensitive condition. Delays in treatment increase the risk of appendiceal perforation (AP), and thus AP rates have been used as a proxy to measure access to surgical care. It is very well known that in Brazil there are big differences between the public and private healthcare systems. Those differences can reflect in the treatment of what are considered simple cases, like appendicitis. As far as we know, it has no known links to behavioral or social risk factors, and has only one treatment option – appendectomy. The purpose of this study was to compare treatment received by Brazilian people, both by those who depend on the public and private healthcare system, and how it affects their outcome.

Methods

Data was collected from the records of all patients submitted to appendectomy, in a public and in a private Sao Paulo city’s hospitals, during January to April of 2010.

Results

Patients admitted by the public hospital present symptoms for a longer period of time than those treated by the private one. It took a significantly higher amount of time for the patients from the public hospital undergo surgery, and their length of stay is also significantly higher.

Conclusions

Appendicitis in a public scenario is associated with increased time from onset of symptoms to operative intervention and the main reason is the delayed presentation. Clinical polices for abdominal pain should be instituted by the public healthcare system, based on population education, healthcare professionals training and establishment of strategies that can speed the diagnosis process up.

Diagnosing appendicitis at different time points in children with right lower quadrant pain: comparison between Pediatric Appendicitis Score and the Alvarado score

BACKGROUND

Acute appendicitis is the most common abdominal emergency in clinical surgery. This study was designed to compare the diagnostic value of the Pediatric Appendicitis Score (PAS) with that of the Alvarado score based on different time points in children with right lower quadrant (RLQ) abdominal pain.

METHODS

This prospective cohort study comprised 1,395 children (aged 3-18 years) with RLQ abdominal pain between 2005 and 2009. The patients were scored by the pediatric emergency physicians. Receiver operating characteristic (ROC) curves were used to determine the appropriate cutoff scores of the Alvarado and PAS systems. The sensitivity and specificity, and area under ROC curve were calculated for both systems.

RESULTS

The AUCs of the Alvarado system were all higher than those of the PAS system (day 1: 0.09 vs. 0.87; day 2: 0.87 vs. 0.84; day 3: 0.88 vs. 0.82). The best appropriate cutoff scores were seven (days 1 and 2) and six (day 3) on the PAS and six (days 1 and 2) and seven (day 3) on the Alvarado system.

CONCLUSIONS

The preliminary data show that the best cutoff score of Alvarado and PAS systems vary with the different time points of RLQ pain presentation. It may provide helpful information for primary or emergency physicians to determine whether the patient should undergo surgical consultation.

The negative appendectomy rate: who benefits from preoperative CT?

OBJECTIVE

The purpose of this article is to determine the negative appendectomy rates of patients who did and did not undergo preoperative CT and to determine, more specifically, whether men benefit from preoperative CT.

MATERIALS AND METHODS

We identified 512 patients who had a nonincidental appendectomy between July 1, 2002, and June 30, 2007. Pathology records were compared with a radiology records search to determine which patients underwent preoperative CT. Proportions of patients were compared between groups using the Fisher exact test.

RESULTS

Of 512 patients who had a nonincidental appendectomy, 465 (91%) underwent preoperative CT, and 47 (9%) underwent appendectomy only on the basis of clinical findings. Overall, 22 of 465 patients (4.7%) who underwent preoperative CT had a negative appendectomy compared with six of 47 patients who did not undergo preoperative imaging (negative appendectomy rate, 12.7%; p = 0.03). Among men, six of 237 (2.5%) with preoperative CT had a negative appendectomy, versus five of 42 without imaging (negative appendectomy rate, 11.9%; p = 0.01).

CONCLUSION

The negative appendectomy rate was decreased for adult patients who underwent preoperative CT compared with patients who did not undergo preoperative imaging. Although most prior studies have suggested that CT is efficacious only in decreasing the negative appendectomy rate among women, we found that men benefit from CT as well.