Ultrasound and CT in the Diagnosis of Appendicitis: Accuracy With Consideration of Indeterminate Examinations According to STARD Guidelines

Machine-learning-assisted Preoperative Prediction of Pediatric Appendicitis Severity

PURPOSE

This study evaluates the effectiveness of machine learning (ML) algorithms for improving the preoperative diagnosis of acute appendicitis in children, focusing on the accurate prediction of the severity of disease.

METHODS

An anonymized clinical and operative dataset was retrieved from the medical records of children undergoing emergency appendectomy between 2014 and 2021. We developed an ML pipeline that pre-processed the dataset and developed algorithms to predict 5 appendicitis grades (1 - non-perforated, 2 - localized perforation, 3 - abscess, 4 - generalized peritonitis, and 5 - generalized peritonitis with abscess). Imputation strategies were used for missing values and upsampling techniques for infrequent classes. Standard classifier models were tested. The best combination of imputation strategy, class balancing technique and classification model was chosen based on validation performance. Model explainability was verified by a pediatric surgeon. Our model's performance was compared to another pediatric appendicitis severity prediction tool.

RESULTS

The study used a retrospective cohort including 1980 patients (60.6 % males, average age 10.7 years). Grade of appendicitis in the cohort was as follows: grade 1-70 %; grade 2-8 %; grade 3-7 %; grade 4-7 %; grade 5-8 %. Every combination of 6 imputation strategies, 7 class-balancing techniques, and 5 classification models was tested. The best-performing combined ML pipeline distinguished non-perforated from perforated appendicitis with 82.8 ± 0.2 % NPV and 56.4 ± 0.4 % PPV, and differentiated between severity grades with 70.1 ± 0.2 % accuracy and 0.77 ± 0.00 AUROC. The other pediatric appendicitis severity prediction tool gave an accuracy of 71.4 %, AUROC of 0.54 and NPV/PPV of 71.8/64.7.

CONCLUSION

Prediction of appendiceal perforation outperforms prediction of the continuum of appendicitis grades. The variables our models primarily rely on to make predictions are consistent with clinical experience and the literature, suggesting that the ML models uncovered useful patterns in the dataset. Our model outperforms the other pediatric appendicitis prediction tools. The ML model developed for grade prediction is the first of this type, offering a novel approach for assessing appendicitis severity in children preoperatively. Following external validation and silent clinical testing, this ML model has the potential to enable personalized severity-based treatment of pediatric appendicitis and optimize resource allocation for its management.

LEVEL OF EVIDENCE: 3

CAR/CETARS/CSAR Practice Guideline on Imaging the Adult Patient With Right Lower Quadrant Pain

In 2023, the Canadian Society of Abdominal Radiology (CSAR) and Canadian Emergency, Trauma, and Acute Care Radiology Society (CETARS) received Canadian Association of Radiologists (CAR) member feedback that there was an unmet educational need for guidance in the imaging investigation of right lower quadrant (RLQ) pain. Members requested specific guidance on how to handle controversial scenarios including which test to order when, specifics of imaging protocols, and managing pregnant patients who have RLQ pain-all from a Canadian perspective. After conducting an exhaustive literature review, the working group agreed that a Canadian-specific set of guidelines was warranted. The management recommendations presented in this guideline were discussed as a group to achieve expert consensus. As the workup for RLQ pain can vary considerably in the paediatric population, the scope of this paper was restricted to adults (18 years of age or older). Whenever possible, the best evidence was used to inform the clinical guidance, and where gaps existed, the guidelines reflect consensus among experts in the field. The result is a framework to aid in this process of managing patients with RLQ pain across various clinical scenarios while addressing current questions and controversies, particularly those most relevant to the Canadian healthcare system.

Open-Access 12-Minute MRI Screening for Acute Appendicitis: A Five-Year Retrospective Observational Study of Diagnostic Accuracy

Objective: This retrospective observational diagnostic accuracy study aims to demonstrate that open-access rapid-sequence non-contrast magnetic resonance imaging (MRI) is accurate for exclusion or confirmation of acute appendicitis (AA). Methods: In 2017, a locally designed 12 min MRI protocol was made available as a new open-access option (no booking needed) for any emergency department (ED) or acute surgical patient with any clinical presentation at the authors' sites. Uninterrupted single-radiologist reporting availability was provided. A 5-year consecutive report list from 1 January 2019 to 31 December 2023 was recorded in an activity log, from which 3478 eligible reports were identified as ED-based referrals assessing for possible AA. There was "appendicitis possibility" in 581/3478 (17%) reports and "no evidence of appendicitis" in 2897/3478 (83%). These were retrospectively compared with the medical record findings of 557/3478 proven cases of AA (16%). Report availability and reliability metrics have been assessed. Results: Overall, 2583/3478 reports (74%) were finalized within 2 h of MRI study completion, 3254/3478 (94%) within 4 h. The 3478 reports combined had 98% sensitivity, 98% specificity, 98% accuracy, 94% positive predictive value, and 99% negative predictive value for AA (φ = 0.95). The largest 5-year subgroup, females 15-19 years old, 66/440 with proven AA, had 98% report accuracy. Pregnant women, 21/171 with proven AA, had 99% report accuracy. Conclusions: The described MRI protocol is accurate for appendicitis assessment and is a suitable first-imaging choice for children, young adults, and pregnant women. It does not require intravenous contrast and poses no radiation risk.

2024 Clinical Practice Guideline Update by the Infectious Diseases Society of America on Complicated Intra-abdominal Infections: Diagnostic Imaging of Suspected Acute Appendicitis in Adults, Children, and Pregnant People

This paper is part of a clinical practice guideline update on the risk assessment, diagnostic imaging, and microbiological evaluation of complicated intra-abdominal infections in adults, children, and pregnant people, developed by the Infectious Diseases Society of America (IDSA). In this paper, the panel provides recommendations for diagnostic imaging of suspected acute appendicitis. The panel's recommendations are based on evidence derived from systematic literature reviews and adhere to a standardized methodology for rating the certainty of evidence and strength of recommendation according to the GRADE (Grading of Recommendations Assessment, Development, and Evaluation) approach.

Evaluating the Diagnostic Efficacy of Computed Tomography in Appendicitis Cases With Negative Ultrasound Findings

INTRODUCTION

Acute appendicitis (AA) is a prevalent cause of abdominal pain, and accurate diagnosis is critical to prevent complications such as perforation. While ultrasound (USG) is often the first imaging modality, its limitations necessitate alternative approaches, particularly in cases where USG results are negative.

OBJECTIVES AND AIMS

This study aims to evaluate the diagnostic accuracy of computed tomography (CT) in identifying appendicitis in patients presenting with negative USG findings.

MATERIALS AND METHODS

A prospective observational study was conducted at a tertiary care hospital in Pondicherry, India, involving 70 patients with clinically suspected appendicitis and negative USG results. All patients underwent CT imaging, and findings were analyzed to determine sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and overall accuracy.

RESULTS

Of the 70 patients, 35 were diagnosed with appendicitis based on CT findings, yielding a sensitivity of 100%, a specificity of 65.71%, a PPV of 74.47%, an NPV of 100%, and an overall accuracy of 82.86%. The study also identified other conditions, such as mesenteric lymphadenitis and ureteric calculus, in patients with negative appendicitis diagnoses.

CONCLUSIONS

CT is a highly effective imaging modality for diagnosing appendicitis in patients with negative USG results. The use of CT significantly aids in clinical decision-making, reducing the rates of unnecessary surgeries and complications.

ACR Appropriateness Criteria® Acute Pelvic Pain in the Reproductive Age Group: 2023 Update

This review focuses on the initial imaging in the reproductive age adult population with acute pelvic pain, including patients with positive and negative beta-human chorionic gonadotropin (β-hCG) levels with suspected gynecological and nongynecological etiology. For all patients, a combination of transabdominal and transvaginal pelvic ultrasound with Doppler is usually appropriate as an initial imaging study. If nongynecological etiology in patients with negative β-hCG is suspected, then CT of the abdomen and pelvis with or without contrast is also usually appropriate. In patients with positive β-hCG and suspected nongynecological etiology, CT of the abdomen and pelvis with contrast and MRI of the abdomen and pelvis without contrast may be appropriate. In patients with negative β-hCG and suspected gynecological etiology, CT of the abdomen and pelvis with contrast, MRI of pelvis without contrast, or MRI of pelvis with and without contrast may be appropriate. The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision process support the systematic analysis of the medical literature from peer reviewed journals. Established methodology principles such as Grading of Recommendations Assessment, Development, and Evaluation or GRADE are adapted to evaluate the evidence. The RAND/UCLA Appropriateness Method User Manual provides the methodology to determine the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where peer reviewed literature is lacking or equivocal, experts may be the primary evidentiary source available to formulate a recommendation.

Impact of COVID-19 on acute appendicitis presentation, management and pathology findings in adult and paediatric populations

BACKGROUND

We investigated the impact of the COVID-19 pandemic on trends of presentation, management and pathology findings in patients who underwent an appendicectomy for suspected acute appendicitis.

METHOD

The retrospective study reviewed patients (n = 939 adults and n = 329 children) who had an appendicectomy performed for suspected acute appendicitis and histopathology assessment in the Belfast Health and Social Care Trust, Northern Ireland. Pre-COVID-19 (March 2019 to February 2020) and COVID-19 Year 1 (March 2020 to February 2021) data were compared. Chi-squared tests were applied to compare timeframes.

RESULTS

513 adult appendicectomies were performed in the immediate year pre-COVID-19, compared to 426 in COVID-19 Year 1, representing a 17% reduction. No such reduction was seen within the paediatric population, likely related to a change in regional paediatric referral criteria during the pandemic. When comparing COVID-19 Year 1 with pre-pandemic, fewer patients presented with <24 hours of symptoms (45% v 53%, p = 0.005), and there was greater use of pre-operative computed tomography imaging in adults (63.2% v 48.7%, p<0.001). Fewer adult and paediatric cases of simple acute appendicitis and non-diagnostic specimens, with relative increased proportions of perforated acute appendicitis, were observed in COVID-19 Year 1 compared with pre-pandemic. No absolute increase in perforated acute appendicitis cases was observed in adults.

CONCLUSION

Year 1 of the COVID-19 pandemic was associated with delayed presentation of acute appendicitis in adults and children. In adults, an overall reduction in appendicectomy operations, increased use of pre-operative diagnostic imaging, and fewer specimens showing simple acute appendicitis or non-diagnostic features, collectively support appropriate restriction of surgery for those patients with a more certain acute appendicitis diagnosis.

Diagnosis and treatment of appendicitis: systematic review and meta-analysis

BACKGROUND

The optimal diagnosis and treatment of appendicitis remains controversial. This systematic review details the evidence and current best practices for the evaluation and management of uncomplicated and complicated appendicitis in adults and children.

METHODS

Eight questions regarding the diagnosis and management of appendicitis were formulated. PubMed, Embase, CINAHL, Cochrane and clinicaltrials.gov/NLM were queried for articles published from 2010 to 2022 with key words related to at least one question. Randomized and non-randomized studies were included. Two reviewers screened each publication for eligibility and then extracted data from eligible studies. Random effects meta-analyses were performed on all quantitative data. The quality of randomized and non-randomized studies was assessed using the Cochrane Risk of Bias 2.0 or Newcastle Ottawa Scale, respectively.

RESULTS

2792 studies were screened and 261 were included. Most had a high risk of bias. Computerized tomography scan yielded the highest sensitivity (> 80%) and specificity (> 93%) in the adult population, although high variability existed. In adults with uncomplicated appendicitis, non-operative management resulted in higher odds of readmission (OR 6.10) and need for operation (OR 20.09), but less time to return to work/school (SMD - 1.78). In pediatric patients with uncomplicated appendicitis, non-operative management also resulted in higher odds of need for operation (OR 38.31). In adult patients with complicated appendicitis, there were higher odds of need for operation following antibiotic treatment only (OR 29.00), while pediatric patients had higher odds of abscess formation (OR 2.23). In pediatric patients undergoing appendectomy for complicated appendicitis, higher risk of reoperation at any time point was observed in patients who had drains placed at the time of operation (RR 2.04).

CONCLUSIONS

This review demonstrates the diagnosis and treatment of appendicitis remains nuanced. A personalized approach and appropriate patient selection remain key to treatment success. Further research on controversies in treatment would be useful for optimal management.

Appendicitis in pregnant women: A systematic review and meta-analysis of the diagnostic performance of ultrasonography

OBJECTIVES

The accuracy of ultrasound in the detection of appendicitis in pregnant women was examined in a meta-analysis.

METHODS

Pregnant women with suspected acute appendicitis were evaluated using ultrasound in a systematic search of PubMed, EMBASE, and Cochrane Library databases from January 1, 2011 to August 10, 2023. The sensitivity and specificity values and diagnostic odds ratios were obtained using the pooled data.

RESULTS

A total of 239 patients were studied in four relevant investigations. Ultrasonography has a sensitivity of 56% and a specificity of 88% for the diagnosis of acute appendicitis, with an area under the receiver operating characteristic curve of 0.66%. Ultrasonography had a positive likelihood ratio of 4.65 (95% confidence interval, 1.42-15.23) and a negative likelihood ratio of 0.50 (95% confidence interval, 0.41-0.62). There was no evidence of publication bias (p = 0.93).

CONCLUSIONS

Ultrasound has moderate sensitivity for identifying appendicitis in pregnant women and may be utilized as an alternative diagnostic method.

When Not to Operate on Acute Cases-A Surgeon's Perspective on Rapid Assessment of Emergency Abdominopelvic Computed Tomography

Clinical problem solving evolves in parallel with advances in technology and discoveries in the medical field. However, it always reverts to basic cognitive processes involved in critical thinking, such as hypothetical-deductive reasoning, pattern recognition, and compilation models. When dealing with cases of acute abdominal pain, clinicians should employ all available tools that allow them to rapidly refine their analysis for a definitive diagnosis. Therefore, we propose a standardized method for the quick assessment of abdominopelvic computed tomography as a supplement to the traditional clinical reasoning process. This narrative review explores the cognitive basis of errors in reading imaging. It explains the practical use of attenuation values, contrast phases, and windowing for non-radiologists and details a multistep protocol for finding radiological cues during CT reading and interpretation. This systematic approach describes the salient features and technical tools needed to ascertain the causality between clinical patterns and abdominopelvic changes visible on CT scans from a surgeon's perspective. It comprises 16 sections that should be read successively and that cover the entire abdominopelvic region. Each section details specific radiological signs and provides clear explanations for targeted searches, as well as anatomical and technical hints. Reliance on imaging in clinical problem solving does not make a decision dichotomous nor does it guarantee success in diagnostic endeavors. However, it contributes exact information for supporting the clinical assessments even in the most subtle and intricate conditions.

Noninflammatory obstructive appendicopathy: A rare presentation of abdominal pain

Patients with appendicitis-like abdominal pain but negative laboratory and radiological findings can have rare alternative aetiologies such as obstructive appendicopathy. A normal appendix may be seen in surgery, and removal with consent is curative.

Use of oral contrast for CT scanning and time to diagnosis and treatment of acute appendicitis

BACKGROUND

The aim of this study was to investigate whether there is a delay in treatment for patients having pre-operative CT imaging with both intravenous and oral contrast (CTIVO) compared to intravenous contrast alone (CTIV).

METHODS

A retrospective review of patients who underwent emergency appendicectomy at a single hospital during a two-year period (1/1/2019-31/12/2020) was performed. Demographic details, imaging timing/modality; biochemical markers; American Society of Anaesthesiologists (ASA) physical status classification, anaesthetic induction time; operative report findings; histopathology, peri-operative complications, admission/discharge times were recorded. The Sunshine Appendicitis Grading System (SAGS) score was used for severity of appendicitis.

RESULTS

Pre-operative CT was performed in 294 patients; CTIVO: 159 (54%), CTIV: 135 (46%). Both groups were comparable for age, sex, ASA status and inflammatory markers. The median time from CT request to scanning was longer with CTIVO (CTIVO: 170 min, CTIV: 65 min, P < 0.0001). The median time from CT request to induction of anaesthesia was also longer with CTIVO (CTIVO: 780 minutes, CTIV: 406 min, P < 0.0001). A delay to theatre was not significantly associated with severity of appendicitis (SAGS score). The diagnostic accuracy was not reduced in the CTIV group compared to the CTIVO group.

CONCLUSION

CTIVO scans significantly delay CT diagnosis and surgical treatment of appendicitis compared to CTIV. Omitting oral contrast does not result in a reduction in diagnostic accuracy for appendicitis.

Ionizing radiation protection and the linear No-threshold controversy: Extent of support or counter to the prevailing paradigm

This study has developed a relationship that categorized radiation protection and allows for a proper, clear, and concise review of the different classifications in terms of principles of protection, dose criteria, categories, fundamental tools, exposure situations, applications and control measures. With the groundwork laid, advances of the linear no-threshold (LNT) model which has attracted attention in the field of radiobiology and epidemiology were examined in detail. Various plausible dose-response relationship scenarios were x-rayed under low-dose extrapolation. Intensive review of factors opposing the LNT model involving radiophobia (including misdiagnosis, alternative surgery/imaging, suppression of ionizing radiation (IR) research); radiobiology (including DNA damage repair, apoptosis/necrosis, senescence protection) and cost issues (including-high operating cost of LNT, incorrect prioritization, exaggeration of LNT impact, risk-to-benefit analysis) were performed. On the other hand, factors supporting the use of LNT were equally examined, they include regulatory bodies' endorsement, insufficient statistical significance, partial DNA repair, variability of irradiated bodies, different latency periods for cancer, dynamic nature of threshold and conflicting interests. After considering the gaps in the scientific investigations that either support or counter the scientific paradigm on the use of LNT model, further research and advocacy is recommended that will ultimately lead to the acceptance of an alternative paradigm by the international regulators.

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.

Multicenter cohort study on the presentation and treatment of acute appendicitis during the COVID-19 pandemic

PURPOSE

Current studies have demonstrated conflicting results regarding surgical care for acute appendicitis during the COVID-19 pandemic. This study aimed to assess trends in diagnosis as well as treatment of acute appendicitis in the Netherlands during the first and second COVID-19 infection wave.

METHODS

All consecutive patients that had an appendectomy for acute appendicitis in nine hospitals from January 2019 to December 2020 were included. The primary outcome was the number of appendectomies for acute appendicitis. Secondary outcomes included time between onset of symptoms and hospital admission, proportion of complex appendicitis, postoperative length of stay and postoperative infectious complications. Outcomes were compared between the pre-COVID group and COVID group.

RESULTS

A total of 4401 patients were included. The mean weekly rate of appendectomies during the COVID period was 44.0, compared to 40.9 in the pre-COVID period. The proportion of patients with complex appendicitis and mean postoperative length of stay in days were similar in the pre-COVID and COVID group (respectively 35.5% vs 36.8%, p = 0.36 and 2.0 ± 2.2 vs 2.0 ± 2.6, p = 0.93). There were no differences in postoperative infectious complications. A computed tomography scan was used more frequently as a diagnostic tool after the onset of COVID-19 compared to pre-COVID (13.8% vs 9.8%, p < 0.001, respectively).

CONCLUSION

No differences were observed in number of appendectomies, proportion of complex appendicitis, postoperative length of stay or postoperative infectious complications before and during the COVID-19 pandemic. A CT scan was used more frequently during the COVID-19 pandemic.

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.

Abdominal Ultrasound and Its Diagnostic Accuracy in Diagnosing Acute Appendicitis: A Meta-Analysis

Background: Acute appendicitis (AA) is a common cause of abdominal pain encountering unnecessary surgeries in emergency departments. The present meta-analysis aims to assess the accuracy of abdominal ultrasound in suspected acute appendicitis cases in terms of sensitivity, specificity, and post-test odds for positive and negative results.

Materials and Methods: An extensive and systematic search was conducted in Medline (via PubMed), Cinahl (via Ebsco), Scopus, and Web of Sciences from 2010 till the end of March 2021. Two authors analyzed studies for inclusion, collected results, and conducted analyses separately. Examination of the histopathological tissue collected during appendectomy served as a gold standard for determining the final diagnosis of appendicitis. The accuracy was determined by evaluating sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), diagnostic odds ratio.

Results: Out of 3,193 references, a total of 18 studies were selected. Overall sensitivity of 77.2% (95% CI – 75.4–78.9%) and specificity of 60% (95% CI – 58–62%) were observed. The diagnostic odds ratio of 6.88(95% CI 1.99–23.82) was obtained.

Conclusion: Abdominal ultrasound shows significant accuracy of diagnosis in patients with suspected acute appendicitis.