Predicting need for additional CT scan in children with a non-diagnostic ultrasound for appendicitis in the emergency department

doi:10.1016/j.ajem.2017.07.005

The American Journal of Emergency Medicine

Volume 36, Issue 1, January 2018, Pages 49-55

https://doi.org/10.1016/j.ajem.2017.07.005 Get rights and content

Abstract

Objective

This study aimed to determine which children with suspected appendicitis should be considered for a computerized tomography (CT) scan after a non-diagnostic ultrasound (US) in the Emergency Department (ED).

Methods

We retrospectively reviewed patients 0–18 year old, who presented to the ED with complaints of abdominal pain, during 2011–2015 and while in the hospital had both US and CT. We recorded demographic and clinical data and outcomes, and used univariate and multivariate methods for comparing patients who did and didn't have appendicitis on CT after non-diagnostic US. Multivariate analysis was performed using logistic regression to determine what variables were independently associated with appendicitis.

Results

A total of 328 patients were enrolled, 257 with non-diagnostic US (CT: 82 had appendicitis, 175 no-appendicitis). Younger children and those who reported vomiting or had right lower abdominal quadrant (RLQ) tenderness, peritoneal signs or White Blood Cell (WBC) count > 10,000 in mm³ were more likely to have appendicitis on CT. RLQ tenderness (Odds Ratio: 2.84, 95%CI: 1.07–7.53), peritoneal signs (Odds Ratio: 11.37, 95%CI: 5.08–25.47) and WBC count > 10,000 in mm³ (Odds Ratio: 21.88, 95%CI: 7.95–60.21) remained significant after multivariate analysis. Considering CT with 2 or 3 of these predictors would have resulted in sensitivity of 94%, specificity of 67%, positive predictive value of 57% and negative predictive value of 96% for appendicitis.

Conclusions

Ordering CT should be considered after non-diagnostic US for appendicitis only when children meet at least 2 predictors of RLQ tenderness, peritoneal signs and WBC > 10,000 in mm³.

Introduction

Acute appendicitis is the most common abdominal emergency in children [1], and early diagnosis is critical in preventing perforation, abscess formation and postoperative complications [2]. History and physical examination alone has a low sensitivity and specificity [3], so imaging may play a key role in the accurate and prompt diagnosis of suspected appendicitis. Computerized tomography (CT) has high sensitivity for diagnosis of appendicitis, and has been used more frequently in the pediatric population in recent years [4]. However, due to radiation exposure [5], providers in the emergency department (ED) are preferring ultrasound (US) as imaging modality [6], [7]. Point of care ultrasound for appendicitis performed in ED has high effectiveness in clinical decision making of ED physicians [8]. Although the specificity of US is high, the sensitivity is variable (50–100%) depending on the operator [9]. It is unclear which children should have advanced imaging after US is considered non-diagnostic when performed by the ED physician [10]. Performing selective CT only for children with non-diagnostic US [11], [12] may reduce CT utilization, but a significant proportion of these children may still have a negative test for appendicitis on CT [11]. The purpose of this study was to determine a method for identification of children who will benefit from a CT scan after a non-diagnostic US.

Section snippets

Methods

We conducted a retrospective study at an urban, tertiary-care hospital in Japan with about 40,000 ED visits per year. Our hospital ethics committees approved the research protocol. We obtained data from the electronic medical record (EMR) system and the hospital electronic administrative system for the period January 1, 2011 through December 31, 2015 in order to identify patients who presented to the ED with complaints of abdominal pain and while in the hospital had both an US exam and

Results

A total of 473 patients with complaints of abdominal pain had both US and CT during the study period. We excluded 129 patients who had [1] imaging studies due to trauma (34, 7.2%), [2] history of appendicitis (11, 2.3%), [3] US or CT documented before presenting to our ED (63, 13.3%), [4] CT performed before US (10, 2.1%), [5] US findings not found in the EMR (11, 2.3%) and [6] suspected other diagnoses than appendicitis based on physical examination, clinical history and US (16, 3.4%). Thus, a

Limitations

Our study has several limitations. This is a retrospective, single-center non-randomized study, where decisions on type of imaging modality were left to the clinician, and practice variation may play a role in our findings. However, we included results from over 50 physicians and findings represent practice in many other EDs. Also, it is possible that some children were discharged after an US and went to another facility where they were diagnosed with appendicitis. Patients who presented with

Discussion

We found that for children with suspected appendicitis and a non-diagnostic US exam by an emergency physician, CT is likely needed only when children have at least two of the following; RLQ tenderness, peritoneal signs or WBC > 10,000 in mm³. If we had applied this decision rule to our study group, we could have avoided about 65% of CT scans that were negative for appendicitis with a much lower false negative rate of 4% (Fig. 3).

Acute appendicitis is the most common cause of abdominal surgical

Author contribution

TN, SM, RG and HH conceived the study, designed the trial. SM, RG and HH supervised the conduct of the trial and data collection. TN, SM, RG, and HH undertook recruitment of patients and managed the data, including quality control. RG provided statistical advice on study design and analyzed the data; SM, RG and HH chaired the data oversight committee. TN drafted the manuscript, and all authors contributed substantially to its revision. TN takes responsibility for the paper as a whole.

Conflicts of interest

Nothing.

Acknowledgement

We would like to thank Mr. Boris Kuzeljevic for his dedicated work on the statistical portion of this work.

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Cited by (7)

Bedside ultrasonography for acute appendicitis: An updated diagnostic meta-analysis
2019, International Journal of Surgery
Citation Excerpt :
The diagnosis of this emergency can be challenging due to atypical symptoms, variable clinical presentation and shared clinical features with other disease status [3]. Recently, modern diagnostic imaging techniques, such as CT scan and ultrasonography are regarded as pivotal diagnostic approaches in acute appendicitis which are shown to improve diagnostic accuracy and patient prognosis [4–7]. Since the application of those imaging modalities, the rate of negative appendectomy and other complications such as appendiceal perforation has considerably decreased.
Bedside ultrasonography is a promising tool for identification of acute appendicitis. We assessed the accuracy and clinical value of bedside ultrasonography for diagnosis of acute appendicitis in the emergency department.
Pubmed, Embase and Cochrane Library were searched from inception to November 2018. The diagnostic accuracy of bedside ultrasonography was compared with that of surgery and/or CT scan, which was used as reference standard. Pooled summary estimates of sensitivity, specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), and diagnostic odds ratio (DOR) from each included study were estimated using bivariate logistic regression model. Inter-study heterogeneity was examined using I² statistic. Meta-regression was performed to further investigate the source of heterogeneity. Deeks's funnel plot was used to test publication bias.
Our search yielded 5394 citations, of which 27 satisfied the inclusion criteria. Bivariate analysis yielded a mean sensitivity of 90% (95% CI 82%–0.95%) and specificity of 95% (95% CI 89%–98%). The area under the receiver operating characteristic curve was 0.97 (95% CI 0.95–0.98). There was significant inter-study heterogeneity (I² = 96%, 95% CI 94%–99%). Meta-regression analysis suggested that study region and patient sample size could attribute to the heterogeneity. Deeks's funnel plot did not indicate the existence of publication bias (P = 0.15).
Bedside ultrasonography, a radiation-free and noninvasive modality, provides superior diagnostic performance in the diagnosis of acute appendicitis, but its value in different abdominal emergencies warrants further development and research.
Utility of applying white blood cell cutoffs to non-diagnostic MRI and ultrasound studies for suspected pediatric appendicitis
2019, American Journal of Emergency Medicine
Citation Excerpt :
A study analyzing this approach provides evidence that it is more cost-effective for ultrasound to be the first-line imaging test despite its shortcomings [11]. Several investigations have combined laboratory test results or other clinical parameters with non-diagnostic ultrasound studies to improve their negative predictive values (NPVs) and thereby avoid the need for additional imaging or admission for observation [6,7,12,13]. No one has investigated whether combining laboratory test results with non-diagnostic MRI studies improves their NPVs.
Non-contrast magnetic resonance imaging (MRI) and ultrasound studies in pediatric patients with suspected appendicitis are often non-diagnostic. The primary objective of this investigation was to determine if combining these non-diagnostic imaging results with white blood cell (WBC) cutoffs improves their negative predictive values (NPVs).
A retrospective chart review was conducted including patients ≤18 years old with suspected appendicitis who had MRI performed with or without a preceding ultrasound study in a pediatric emergency department. Imaging results were sorted into 2 diagnostic and 5 non-diagnostic categories. NPVs were calculated for the non-diagnostic MRI and ultrasound categories with and without combining them with WBC cutoffs of <10.0 and <7.5 × 10⁹/L.
Of the 612 patients with MRI studies included, 402 had ultrasound studies performed. MRI with incomplete visualization of a normal appendix without secondary signs of appendicitis had an NPV of 97.9% that changed to 98.1% and 98.2% when combined with WBC cutoffs of <10.0 and <7.5, respectively. Ultrasound studies with incomplete visualization of a normal appendix without secondary signs had an NPV of 85.3% that improved to 94.8% and 96.5% when combined with WBC cutoffs of <10.0 and <7.5, respectively.
In pediatric patients with suspected appendicitis, MRI studies with incomplete visualization of a normal appendix without secondary signs have a high NPV that does not significantly change with the use of these WBC cutoffs. In contrast, combining WBC cutoffs with ultrasound studies with the same interpretation identifies low-risk groups.
Reliability of standardized reporting system of acute appendicitis in adults at low-dose 320-rows CT
2019, European Journal of Radiology Open
Citation Excerpt :
Ultrasound is favored by some physicians but it has lower sensitivity and limited by operator dependence, patient body habitus [9]. Many researchers have also tried to use color Doppler imaging to detect blood flow in the wall of the appendix, but this has shown only a marginal increase in the sensitivity to 87 % for detecting acute appendicitis [10]. Elastography is recently applied to assess appendicitis but it is in early stages [11].
To assess the reliability of a standardized reporting system of acute appendicitis at low-dose 320-rows CT.
Retrospective analysis CT of 78 patients with pathologically proven acute appendicitis. The study was performed at a low-dose 320-rows CT. The image analysis was performed by 2 radiologists according to a standardized reporting system of acute appendicitis.
There was an excellent overall of the inter-observer agreement of both observers for the standardized reporting system of acute appendicitis (K = 0.89, 95 % CI = 0.87-0.92, P = 0.001). There was good inter-observer agreement for visualization of the appendix (K = 0.78, P = 0.001), the tip diameter (K = 0.75, P = 0.001), and a single wall thickness of appendix (K = 0.77, P = 0.001). There was excellent inter-observer agreement for outer to outer wall diameter (K = 0.82, P = 0.001), mucosal hyper-enhancement (K = 0.80, P = 0.001), appendicolith (K = 0.86, P = 0.001), gas in the appendix (K = 0.82, P = 0.001), surrounding fat stranding (K = 0.81, P = 0.001), focal cecal thickening (K = 0.85, P = 0.001), peri-appendiceal air (K = 0.87, P = 0.001), peri-appendicular fluid collection, phlegmon, or abscess (K = 0.82, P = 0.001), and right ovary cyst (K = 0.83, P = 0.001).
we concluded that excellent reliability of a standardized reporting system of acute appendicitis in the adults using low-dose 320-rows CT.
Magnetic Resonance Imaging Provides Useful Diagnostic Information Following Equivocal Ultrasound in Children With Suspected Appendicitis
2021, Canadian Association of Radiologists Journal
Proper pre-operative observation time reduces the incidence of unnecessary appendectomy in managing suspected acute appendicitis in children
2020, Pakistan Journal of Medical and Health Sciences
Are We Doing Enough to Reduce Ionizing Radiation Exposure in Children?: An Analysis of Current Approaches to Pediatric Appendicitis Imaging at a Major Urban Medical Center
2020, Pediatric Emergency Care

View all citing articles on Scopus

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Original ContributionPredicting need for additional CT scan in children with a non-diagnostic ultrasound for appendicitis in the emergency department☆

Abstract

Objective

Methods

Results

Conclusions

Introduction

Section snippets

Methods

Results

Limitations

Discussion

Author contribution

Conflicts of interest

Acknowledgement

Ann Emerg Med

Ann Emerg Med

Lancet

J Pediatr Surg

J Emerg Med

J Pediatr

Ann Emerg Med

J Pediatr

J Surg Res

Ann Emerg Med

J Am Coll Surg

The epidemiology of appendicitis and appendectomy in the United States

Am J Epidemiol

Does this child have appendicitis?

JAMA

Diagnostic accuracy of emergency physician performed graded compression ultrasound study in acute appendicitis: a prospective study

J Ultrasound

Bedside ultrasonography as an adjunct to routine evaluation of acute appendicitis in the emergency department

West J Emerg Med

Diagnostic value and effect of bedside ultrasound in acute appendicitis in the emergency department

Acad Emerg Med

US or CT for diagnosis of appendicitis in children and adults? A meta-analysis

Radiology

Effectiveness of a staged US and CT protocol for the diagnosis of pediatric appendicitis: reducing radiation exposure in the age of ALARA

Radiology

Original Contribution
Predicting need for additional CT scan in children with a non-diagnostic ultrasound for appendicitis in the emergency department☆