Anatomic Reasons for Failure to Visualize the Appendix With Graded Compression Sonography: Insights From Contemporaneous CT

"Rule out appendicitis": a Canadian emergency radiology perspective on medicolegal risks, imaging pitfalls, and strategies to improve care

We provide a unique Canadian perspective on the medicolegal risks associated with imaging acute appendicitis, incorporating data requested from the Canadian Medical Protective Association (CMPA) on closed medicolegal cases over the past decade. We include a review of current clinical and imaging guidelines in the diagnosis and management of this common emergency room presentation. A case-based approach is implemented in this article to explore ways to mitigate potential errors in the diagnosis of acute appendicitis.

Factors Contributing to Nonvisualization of the Appendix on Ultrasound in Children With Suspected Appendicitis

OBJECTIVE

This study aimed to identify the patient characteristics, history factors, physical examination findings, and sonographic findings, which contribute to a higher risk of the appendix not being visualized on ultrasound evaluation (ie, nondiagnostic or equivocal study) in patients being evaluated for appendicitis. Secondarily, this study assessed the utility of an equivocal ultrasound, specifically in the ability to predict the absence of appendicitis.

METHODS

A retrospective case review was performed, of children (age, 0-18 years) presenting to a pediatric emergency department with clinical suspicion for appendicitis, who underwent sonographic studies during the 12-month study period.

RESULTS

Five hundred forty-three cases were reviewed, of which 75 (14%) were diagnosed with appendicitis. The sensitivity of ultrasound diagnosis of appendicitis was 62.7% and specificity was 79.1%. The appendix was not visualized in 398 (73%) cases. Of the cases where the appendix was not visualized, 370 did not have appendicitis (negative predictive value, 93%). In cases where the appendix was not visualized and the white blood cell count was less than 10,000, the negative predictive value rose to 97%. The patient's age (odds ratio [OR], 1.049), weight (OR, 1.015), presence of appendicolith (OR, 0.426), presence of right lower quadrant fat stranding on sonography (OR, 0.081), and presence of hyperemia on sonography (OR, 0.094) were found to be significant in affecting the visualization of the appendix on ultrasound.

CONCLUSIONS

Increasing patient's age and weight leads to increased likelihood that the appendix will not be visualized on ultrasound, whereas the presence of an appendicolith, right lower quadrant fat stranding or hyperemia will increase the likelihood of visualization. The sensitivity and specificity of ultrasound for the diagnosis of appendicitis are moderate but the negative predictive value of an equivocal study is high. Clinicians can use supporting clinical examination and laboratory findings, in conjunction with a nondiagnostic ultrasound evaluation of the appendix to exclude the diagnosis of appendicitis, without the need for further imaging.

Pre-Coronavirus Disease 2019 Pediatric Acute Appendicitis: Risk Factors Model and Diagnosis Modality in a Developing Low-Income Country

PURPOSE

Pediatric acute appendicitis has a stable incidence rate in Western countries with an annual change of -0.36%. However, a sharp increase was observed in the Asian region. The Indonesian Health Department reveals appendicitis as the fourth most infectious disease, with more than 64,000 patients annually. Hence, there is an urgent need to identify and evaluate the risk factors and diagnostic modalities for accurate diagnosis and early treatment. This study also clarifies the usage of pediatric appendicitis score (PAS) for children <5 years of age.

METHODS

The current study employed a cross-sectional design with purposive sampling through demographic and PAS questionnaires with ultrasound sonography (USG) results. The analysis was performed using the chi-square and Mann-Whitney tests and logistic regression.

RESULTS

This study included 21 qualified patients with an average age of 6.76±4.679 years, weighing 21.72±10.437 kg, and who had been hospitalized for 4.24±1.513 days in Siloam Teaching Hospital. Compared to the surgical gold standard, PAS and USG have moderate sensitivity and specificity. Bodyweight and stay duration were significant for appendicitis (p<0.05); however, all were confounders in the multivariate regression analysis. Incidentally, a risk prediction model was generated with an area under the curve of 72.73%, sensitivity of 100.0%, specificity of 54.5%, and a cut-off value of 151.

CONCLUSION

PAS outperforms USG in the sensitivity of diagnosing appendicitis, whereas USG outperforms PAS in terms of specificity. This study demonstrates the use of PAS in children under 5 years old. Meanwhile, no risk factors were significant in multivariate pediatric acute appendicitis risk factors.

Classification of acute appendicitis (CAA): treatment directed new classification based on imaging (ultrasound, computed tomography) and pathology

PURPOSE

Acute appendicitis (AA) is amongst the most common causes of acute abdominal pain. In spite of progress based on risk stratifications, "negative" appendectomies are performed in up to 30% of patients whilst the appendix perforates in others. Preoperative classification of AA based on imaging is therefore recommended. The aim was to classify AA based on imaging (ultrasound/US, computed tomography/CT), surgical pathology, and/or histopathology in order to differentiate between complicated and uncomplicated AA. A new classification of acute appendicitis (CAA) shall be illustrated by typical US and CT images and be employed in a diagnostic and therapeutic algorithm.

METHODS

Medline, Embase, and the Cochrane Library were searched. Any study after 1970, which investigated clinical scores, pathology, US, CT, magnetic resonance imaging, and treatment of AA, was included. Typical images were taken from the author's image database.

RESULTS

Five main types of AA are defined, normal appendix (type 0), nonvisualised appendix (type X), uncomplicated AA (type 1), complicated AA without perforation (type 2), and complicated AA with perforation (type 3). The imaging modality is indicated by an additional letter, e.g., type p3b for free perforation on pathology. Standardised reporting of the appendix evaluation by US and CT is presented, as well as algorithms for AA management. Imaging features indicating imminent perforation, as well as likely recurrence, were both classified as complicated AA.

CONCLUSION

Imaging is mandatory in suspected AA. The CAA clearly separates uncomplicated from complicated forms of AA allowing nonoperative management in selected patients with uncomplicated forms of AA.

Diagnostic performance of US for suspected appendicitis: Does multi-categorical reporting provide better estimates of disease in adults, and what factors are associated with false or indeterminate results?

PURPOSE

To identify factors associated with false or indeterminate US result for suspected appendicitis, and assess whether multi-categorical reporting of US yields more precise estimates regarding the probability of appendicitis.

METHODS

562 US examinations for suspected appendicitis between May 2013-April 2015 were categorized as true (77/562 true positives or true negatives) or false/indeterminate (485/562 false negatives, false positives or indeterminates) based on results from a prior study. Of 541 examinations with images available retrospectively, a category of A-E was assigned as follows: non-visualized appendix with secondary findings (A) absent or (B) present; appendix visualized and considered (C) negative, (D) equivocal, or (E) positive for appendicitis. The following factors were recorded: age; sex; scan time (daytime vs. off-hours); resident/fellow involvement; abdominal subspecialty radiologist; radiologist experience (>5 years or not); and tenderness on interrogation. Associations between factors and US result were assessed (t-tests, Fisher's exact test and multivariate logistic regression).

RESULTS

The true group had proportionally more males (18/77 (23.4%) vs. 66/485 (13.6%), p = 0.04) and patients with sonographic tenderness (43/77 (55.8%) vs. 132/353 (27.3%), p < 0.0001). There was no significant difference or association with other factors. On multivariate logistic regression, false/indeterminate results were 1.9 times (95% CIs 1.0-3.5) more likely among females and 3.8 times more likely in the absence of tenderness (95% CIs 2.3-6.4). The proportion of patients with appendicitis in categories A-E was 34/410 (8.3%), 24/44 (54.5%), 0/18 (0%), 0/3 (0%) and 61/66 (92.4%), respectively.

CONCLUSIONS

Females and absence of tenderness were associated with a false/indeterminate US. Categorical reporting provides more granular estimates of the post-test probability of appendicitis.

Sonographic diagnosis of appendicitis: A pictorial essay and a new diagnostic maneuver

While many cases of appendicitis are easy to diagnose clinically, a significant number need further workup in the form of imaging. Ultrasound and CT are both used extensively to diagnose or exclude appendicitis, or arrive at an alternate diagnosis. Ultrasound has many advantages but can be a difficult modality to use due to, among other reasons, the anatomical variations in appendicial location. The true retrocolic appendix is particularly difficult to diagnose with ultrasound. This pictorial essay examines the ultrasound features of normal and diseased appendix and proposes a new examining station, the prone view, for visualizing true retrocolic appendicitis.

The Borderline-Size Appendix: Grayscale, Color Doppler, and Spectral Doppler Findings That Improve Specificity for the Sonographic Diagnosis of Acute Appendicitis

Diagnostic criteria for acute appendicitis using graded compression sonography have been well established based on the maximum outer diameter (MOD) of the appendix, with MOD values of <6 mm nearly always indicating normal appendices and MOD values of >8 mm nearly always indicating appendicitis. However, the "borderline-size" appendix, meaning one whose MOD lies between these ranges (ie, an appendix with MOD of 6-8 mm), presents a diagnostic dilemma because appendices in this size range are neither clearly normal nor abnormal when diagnosis is based on the MOD alone; accordingly, such borderline MOD values are diagnostically equivocal, and sonographic diagnosis must rely on sonographic findings other than the MOD. The goal of this review was to examine the additional sonographic findings that can add specificity and help enable an accurate diagnosis to be made in patients with borderline-size appendices.

Suspicion of acute appendicitis in adults. The value of ultrasound in our hospital

OBJECTIVE

To evaluate the accuracy of ultrasonography for the diagnosis of acute appendicitis in adults, to calculate the negative appendicectomy rate in operated patients and the accuracy of pre-defined diagnostic categories and to identify statistically significant signs and symptoms of acute appendicitis in ultrasonography.

MATERIAL AND METHODS

Descriptive prospective study in which we collected the findings of the urgent ultrasonographies ordered in a one-year period for adult patients with pain in the right iliac fossa (RIF), along with their symptoms. We classified them in 5 different diagnostic categories presented in the radiological report: normal appendix, non-visible appendix and no secondary signs, non-conclusive, probable appendicitis, certain appendicitis. By mean of the Stata14 software descriptive analysis, T-test and Chi-square were performed and the data were compared with the final pathological report.

RESULTS

Population: 139 patients (45% men, 55% women), mean age: 32,68 (15-84). Prevalence of acute appendicitis: 50,35% (70/139). Negative appendicectomy rate: 0%. Negative predictive value for the categories 1,2 and 3 taken together: 90,78%. Positive predictive value for the categories 4 and 5 taken together: 100%. Ultrasound sensibility and specificity 90% and 100%, respectively. Statistically significant signs and symptoms (p<0.05): RIF pain, fever, leukocytosis, left shift, visible appendix, non-compressibility, hyperechogenic fat, appendicolith and free fluid.

CONCLUSION

Ultrasound is very accurate for the diagnosis of acute appendicitis in adults.