Ultrasound Assessment in Children With Suspected Appendicitis: Time to Revise Diagnostic Criteria: A Prospective Cohort Study.

Background: Although ultrasound is considered the gold standard for the evaluation of children with suspected appendicitis, there is still much debate about the most accurate ultrasound findings. The purpose of this study was to define the best ultrasound signs that could ultimately improve the diagnostic accuracy of ultrasound for diagnosing pediatric acute appendicitis, and to differentiate between simple appendicitis and complicated appendicitis. Patients and Methods: After approval by our Institutional Review Board, a prospective study was carried out from January 1, 2022, to July 31, 2023, in a pediatric emergency department. We included all patients aged under 14 years with suspected appendicitis and ultrasound-visualized appendix. Results: A total of 550 patients presented with suspected appendicitis during the study period. Of these children, 411 had an ultrasound-visualized appendix. Our patients' mean age was 9.4 years. The best positive predictive value of ultrasound was found for appendiceal diameter ≥7.5 mm. The combination of an appendiceal diameter <6 mm and the lack of peri-appendiceal free fluid on ultrasound rules out the diagnosis of appendicitis. The best diagnostic accuracy of ultrasound, which was 92%, was achieved for appendix diameters ≥6.5 mm. The sonographic sign giving the best ultrasound accuracy for diagnosing complicated appendicitis was an appendix diameter ≥9 mm. Conclusions: In conclusion, our present study demonstrated that appendiceal diameter ≥6.5 mm is the gold standard for diagnosing appendicitis in pediatric patients. The combination of an appendiceal diameter <6 mm and the lack of peri-appendiceal free fluid on ultrasound would rule out appendicitis.

The application value of high-frequency ultrasound in the feasibility assessment of endoscopic retrograde appendicitis therapy in children with appendicitis.

Acute appendicitis is one of the common acute abdominal diseases in pediatrics. However, the implementation of radiological examination guided endoscopic retrograde appendicitis therapy (ERAT) in adults is limited in children. Our previous research explored the non-invasive guidance of high-frequency ultrasound (HFUS) for ERAT and achieved good therapeutic effects. This study mainly focuses on exploring the application value of HFUS in the feasibility assessment of ERAT in children with appendicitis. 163 children with appendicitis received ERAT guided by HFUS were analyzed retrospectively. According to the parameters evaluated by HFUS before and during ERAT, the results indicated that the distance between the appendix orifice and the ileocecal valve significantly affected the time required for the guidewire to enter the appendix cavity (P < 0.05). The diameter and the texture of the fecalith, the thickness of the intestinal wall of the appendiceal orifice all had significant effects on the successful removal of the fecalith (P < 0.05). The success rate, treatment time and final flushing effect of the guidewire to reach the blind end of the appendix were significantly affected by the tortuosity of the appendix and whether there was adhesion with surrounding tissues (P < 0.05). HFUS can accurately assess the feasibility of ERAT in children with appendicitis.

Rapid MRI Abdomen for Assessment of Clinically Suspected Acute Appendicitis in the General Adult Population: a Systematic Review.

OBJECTIVES: To perform a systematic review on the use of magnetic resonance imaging (MRI) of the abdomen to evaluate clinically suspected appendicitis in the general adult population. We examined the diagnostic accuracy, the reported trends of MRI use, and the factors that affect the utility of MRI abdomen, including study duration and cost-benefits. METHODS: We conducted a systematic literature search on PubMed, MEDLINE, Embase, Web of Science, and Cochrane Library databases. We enrolled primary studies investigating the use of MRI in diagnosing appendicitis in the general adult population, excluding studies that predominantly reported on populations not representative of typical adult appendicitis presentations, such as those focusing on paediatric or pregnant populations. RESULTS: Twenty-seven eligible primary studies and 6 secondary studies were included, totaling 2,044 patients from eight countries. The sensitivity and specificity of MRI for diagnosing appendicitis were 96% (95% CI: 93-97%) and 93% (95% CI: 80-98%), respectively. MRI can identify complicated appendicitis and accurately propose alternative diagnoses. The duration of MRI protocols in each primary study ranged between 2.26 and 30 minutes, and only one study used intravenous contrast agents in addition to the non-contrast sequences. Decision analysis suggests significant benefits for replacing computed tomography (CT) with MRI and a potential for cost reduction. Reported trends in MRI usage showed minimal utilisation in diagnostic settings even when MRI was available. CONCLUSIONS: MRI accurately diagnoses appendicitis in the general adult population and improves the identification of complicated appendicitis or alternative diagnoses compared to other modalities using a single, rapid investigation.

Racial and insurance status disparities in imaging modality among pediatric patients diagnosed with appendicitis.

BACKGROUND: Studies have assessed the type of diagnostic imaging used in the treatment of appendicitis in children. Few studies investigated racial/ethnic and insurance disparities in imaging modalities used in pediatric patients diagnosed with appendicitis. Our study seeks to determine whether race/ethnicity and insurance status are associated with imaging modality chosen for pediatric patients diagnosed with appendicitis in the emergency department. METHODS: This was a retrospective cohort study utilizing data from the National Hospital Ambulatory Medical Care Survey (NHAMCS) from 2010 to 2019. We included children <18 years old with a ICD-9-CM and ICD-10-CM diagnosis of appendicitis. Exposures were patient race/ethnicity and insurance status. Outcome of interest was imaging modality. We conducted adjusted survey logistic regression to evaluate the patient characteristics and receipt each of the imaging modalities among those with a diagnosis of appendicitis. RESULTS: Of 308,140,115 emergency department (ED) visits, 1,126,865 (0.37%) had a diagnosis of appendicitis. Overall, male patients were more likely to receive CAT scan in comparison to female children (OR=2.52, 95% CI= 1.16-5.49). Additionally, Hispanic children who had significantly greater odds of obtaining ultrasound (OR= 4.56, 95% CI=1.09-19.12). Hispanic children were also less likely to receive x-ray (OR= 0.31, 95% CI=0.11-0.89) or computed tomography (CT) scans (OR= 0.23, 95% CI=0.07-0.76). Children diagnosed with appendicitis who had insurance other than private, Medicare, Medicaid, or self-pay were significantly more likely to receive x-ray studies (OR=4.39, 95% CI= 1.23-15.69). CONCLUSIONS AND GLOBAL HEALTH IMPLICATIONS: This study demonstrated the presence of racial/ethnic and insurance status disparities in the imaging modality chosen to assist in diagnosing appendicitis in pediatric patients.

The Development and Validation of Artificial Intelligence Pediatric Appendicitis Decision-Tree for Children 0 to 12 Years Old.

INTRODUCTION: Diagnosing appendicitis in young children (0-12 years) still poses a special difficulty despite the advent of radiological investigations. Few scoring models have evolved and been applied worldwide, but with significant fluctuations in accuracy upon validation. AIM: To utilize artificial intelligence (AI) techniques to develop and validate a diagnostic model based on clinical and laboratory parameters only (without imaging), in addition to prospective validation to confirm the findings. METHODS: In Stage-I, observational data of children (0-12 years), referred for acute appendicitis (March 1, 2016-February 28, 2019, n = 166), was used for model development and evaluation using 10-fold cross-validation (XV) technique to simulate a prospective validation. In Stage-II, prospective validation of the model and the XV estimates were performed (March 1, 2019-November 30, 2021, n = 139). RESULTS: The developed model, AI Pediatric Appendicitis Decision-tree (AiPAD), is both accurate and explainable, with an XV estimation of average accuracy to be 93.5% ± 5.8 (91.4% positive predictive value [PPV] and 94.8% negative predictive value [NPV]). Prospective validation revealed that the model was indeed accurate and close to the XV evaluations, with an overall accuracy of 97.1% (96.7% PPV and 97.4% NPV). CONCLUSION: The AiPAD is validated, highly accurate, easy to comprehend, and offers an invaluable tool to use in diagnosing appendicitis in children without the need for imaging. Ultimately, this would lead to significant practical benefits, improved outcomes, and reduced costs.

Ultrasound assessment of gastric contents in children before general anaesthesia for acute appendicitis.

There is increasing evidence that a minority of adults with acute appendicitis have gastric contents, posing an increased risk of pulmonary aspiration. This study aimed to evaluate the proportion of children with acute appendicitis who have gastric contents considered to pose a higher risk of pulmonary aspiration. We analysed point-of-care gastric ultrasound data routinely collected in children before emergency appendicectomy in a specialist paediatric hospital over a 30-month period. Based on qualitative and quantitative antral assessment in the supine and right lateral decubitus positions, gastric contents were classified as 'higher-risk' (clear liquid with calculated gastric fluid volume > 0.8 ml.kg-1 , thick liquid or solid) or 'lower-risk' of pulmonary aspiration. The 115 children studied had a mean (SD) age of 11 (3) years; 37 (32%; 95%CI: 24-42%) presented with higher-risk gastric contents, including 15 (13%; 95%CI: 8-21%) with solid/thick liquid contents. Gastric contents could not be determined in 13 children as ultrasound examination was not feasible in the right lateral decubitus position. No cases of pulmonary aspiration occurred. This study shows that gastric ultrasound is feasible in children before emergency appendicectomy. This technique showed a range of gastric content measurements, which could contribute towards defining the risk of pulmonary aspiration.

Abdominal fellowship-trained versus generalist radiologist accuracy when interpreting MR and CT for the diagnosis of appendicitis.

OBJECTIVES: To compare the diagnostic accuracy of generalist radiologists working in a community setting against abdominal radiologists working in an academic setting for the interpretation of MR when diagnosing acute appendicitis among emergency department patients. METHODS: This observational study examined MR image interpretation (non-contrast MR with diffusion-weighted imaging and intravenous contrast-enhanced MR) from a prospectively enrolled cohort at an academic hospital over 18 months. Eligible patients had an abdominopelvic CT ordered to evaluate for appendicitis and were > 11 years old. The reference standard was a combination of surgery and pathology results, phone follow-up, and chart review. Six radiologists blinded to clinical information, three each from community and academic practices, independently interpreted MR and CT images in random order. We calculated test characteristics for both individual and group (consensus) diagnostic accuracy then performed Chi-square tests to identify any differences between the subgroups. RESULTS: Analysis included 198 patients (114 women) with a mean age of 31.6 years and an appendicitis prevalence of 32.3%. For generalist radiologists, the sensitivity and specificity (95% confidence interval) were 93.8% (84.6-98.0%) and 88.8% (82.2-93.2%) for MR and 96.9% (88.7-99.8%) and 91.8% (85.8-95.5%) for CT. For fellowship-trained radiologists, the sensitivity and specificity were 96.9% (88.2-99.5%) and 89.6% (82.8-94%) for MR and 98.4% (90.5-99.9%) and 93.3% (87.3-96.7%) for CT. No statistically significant differences were detected between radiologist groups (p = 1.0, p = 0.53, respectively) or when comparing MR to CT (p = 0.21, p = 0.17, respectively). CONCLUSIONS: MR is a reliable, radiation-free imaging alternative to CT for the evaluation of appendicitis in community-based generalist radiology practices. KEY POINTS: • There was no significant difference in MR image interpretation accuracy between generalist and abdominal fellowship-trained radiologists when evaluating sensitivity (p = 1.0) and specificity (p = 0.53). • There was no significant difference in accuracy comparing MR to CT imaging for diagnosing appendicitis for either sensitivity (p = 0.21) or specificity (p = 0.17). • With experience, generalist radiologists enhanced their MR interpretation accuracy as demonstrated by improved interpretation sensitivity (OR 2.89 CI 1.44-5.77, p = 0.003) and decreased mean interpretation time (5 to 3.89 min).

Effect of Clinical Decision Support on Diagnostic Imaging for Pediatric Appendicitis: A Cluster Randomized Trial.

Importance: Appendicitis is the most common pediatric surgical emergency. Efforts to improve efficiency and quality of care have increased reliance on computed tomography (CT) and ultrasonography (US) in children with suspected appendicitis. Objective: To evaluate the effectiveness of an electronic health record-linked clinical decision support intervention, AppyCDS, on diagnostic imaging, health care costs, and safety outcomes for patients with suspected appendicitis. Design, Setting, and Participants: In this parallel, cluster randomized trial, 17 community-based general emergency departments (EDs) in California, Minnesota, and Wisconsin were randomized to the AppyCDS intervention group or usual care (UC) group. Patients were aged 5 to 20 years, presenting for an ED visit with right-sided or diffuse abdominal pain lasting 5 days or less. We excluded pregnant patients, those with a prior appendectomy, those with selected comorbidities, and those with traumatic injuries. The trial was conducted from October 2016 to July 2019. Interventions: AppyCDS prompted data entry at the point of care to estimate appendicitis risk using the pediatric appendicitis risk calculator (pARC). Based on pARC estimates, AppyCDS recommended next steps in care. Main Outcomes and Measures: Primary outcomes were CT, US, or any imaging (CT or US) during the index ED visit. Safety outcomes were perforations, negative appendectomies, and missed appendicitis. Costs were a secondary outcome. Ratio of ratios (RORs) for primary and safety outcomes and differences by group in cost were used to evaluate effectiveness of the clinical decision support tool. Results: We enrolled 3161 patients at intervention EDs and 2779 patients at UC EDs. The mean age of patients was 11.9 (4.6) years and 2614 (44.0%) were boys or young men. RORs for CT (0.94; 95% CI, 0.75-1.19), US (0.98; 95% CI, 0.84-1.14), and any imaging (0.96; 95% CI, 0.86-1.07) did not differ by study group. In an exploratory analysis conducted in 1 health system, AppyCDS was associated with a reduction in any imaging (ROR, 0.82; 95% CI, 0.73- 0.93) for patients with pARC score of 15% or less and a reduction in CT (ROR, 0.58; 95% CI, 0.45-0.74) for patients with a pARC score of 16% to 50%. Perforations, negative appendectomies, and cases of missed appendicitis by study phase did not differ significantly by study group. Costs did not differ overall by study group. Conclusions and Relevance: In this study, AppyCDS was not associated with overall reductions in diagnostic imaging; exploratory analysis revealed more appropriate use of imaging in patients with a low pARC score. Trial Registration: ClinicalTrials.gov Identifier: NCT02633735.

Leveraging the Combined Predictive Value of Ultrasound and Laboratory Data to Reduce Radiation Exposure and Resource Utilization in Children with Suspected Appendicitis.

BACKGROUND: Previous investigation has shown that the combined predictive value of white blood cell count and ultrasound (US) findings to be superior to either alone in children with suspected appendicitis. The purpose of this study was to evaluate the impact of a diagnostic clinical pathway (DCP) leveraging the combined predictive value of these tests on computed tomography (CT) utilization and resource utilization. METHODS: Retrospective cohort study comparing 8 mo of data before DCP implementation to 18 mo of data following implementation. The pathway incorporated decision-support for disposition (operative intervention, observation, or further cross-sectional imaging) based on the combined predictive value of laboratory and US data (stratifying patients into low, moderate, and high-risk groups). Study measures included CT and magnetic resonance imaging utilization, imaging-related cost, time to appendectomy, and negative appendectomy rate. RESULTS: Ninety-seven patients in the preintervention period were compared with 319 patients in the postintervention period. Following DCP implementation, CT utilization decreased by 86% (21% versus 3%, P < 0.001). Mean time to appendectomy decreased from 8.5 to 7.2 h (P < 0.001), and the negative appendectomy rate remained unchanged (5% versus 4%, P = 0.54). Magnetic resonance imaging utilization increased following pathway implementation (1% versus 7%, P = 0.02); however, median imaging-related cost was significantly lower in the postimplementation period ($283/case to $270/case, P = 0.002) CONCLUSIONS: In children with suspected appendicitis, implementation of a DCP leveraging the combined predictive value of white blood cell and US data was associated with a reduction in CT utilization, time to appendectomy, and imaging-related cost.

Computed Tomography for Acute Appendicitis Diagnosis and Confirmation in Men : Trends and Cost Implications.

INTRODUCTION: The classic findings of acute appendicitis-right lower quadrant pain, anorexia, and leukocytosis-have been well known. However, emergency medicine and surgical providers continue to rely on imaging to confirm the diagnosis. We aimed to evaluate the increase in reliance on computed tomography (CT) scans for acute appendicitis diagnosis over time. METHODS: We conducted a retrospective study of patients ≥18 years presenting to UNC Hospitals with signs and symptoms of acute appendicitis who subsequently underwent appendectomy from 2011 to 2015. Demographic, clinical, laboratory, and pathologic data were reviewed. We evaluated the incidence of CT scans stratified by year, age, and sex. RESULTS: Within our male population, 55.2% (278/504) had classic appendicitis symptoms. Of the 278 male patients with classic appendicitis symptoms, 248 underwent CT imaging. Male patients <45 years of age were more likely to present with classic appendicitis symptoms (216/357, 60.5%) compared with patients aged 46-65 (52/108, 48.1%) or >65 (10/39, 25.6%). Of the male patients <45 years with classic appendicitis symptoms, the incidence of CT scans increased over time (68.3% in 2011, 84.2% in 2012, 92.3% in 2013, 93.9% in 2014, 92.3% in 2015). When considering the 216 CT scans that could have been avoided in our population, we calculate an approximate savings of $173 998.80 over 5 years. CONCLUSION: The incidence of CT scans for acute appendicitis confirmation has increased over time even in men. CT scans for the diagnosis or confirmation of acute appendicitis should rarely be indicated in men aged <45 years with classic appendicitis symptoms.

Value Assessment of Evolving Pediatric Appendicitis Imaging Strategies Between 2004 and 2018.

OBJECTIVE: To assess diagnostic imaging utilization and the proportion of negative appendectomies for pediatric appendicitis at US children's hospitals between 2004 and 2018. METHODS: This was a retrospective study using data from the Pediatric Health Information System (PHIS) database. Pediatric patients (age: 0-17 years) who underwent an appendectomy at one of 32 children's hospitals from January 1, 2004, through September 30, 2018, were included. Patients were identified based on International Classification of Diseases, 9th revision and International Classification of Diseases, 10th revision procedure codes. Patient demographics, imaging performed, and the frequency of negative appendectomy were analyzed. RESULTS: The final study population consisted of 104,033 children. From 2004 to 2018, CT utilization decreased from 56.8% (2,951 of 5,198) to 18.6% (1,201 of 6,455; P < .001). Ultrasound utilization increased from 26.4% (1,371 of 5,198) to 63.4% (4,093 of 6,455; P < .001). Radiography utilization remained stable at 16.7% (870 of 5,198) and 15.8% (1,018 of 6,455; P = .160). MRI use increased from 0.1% (6 of 5,198) to 2.2% (143 of 6,455; P < .001). During the study period, the negative appendectomy rate slightly decreased, from 3.74% (4,742 of 126,778 in 2004-2011) to 3.14% (4,258 of 135,561 in 2012-2018; P < .001). CONCLUSION: There has been a shift in imaging of children with appendicitis over 15 years in the United States, because the use of CT has decreased and ultrasound use has increased. This shift has likely added value to the health care system without adversely affecting outcomes (negative appendectomy rate).

Pre-Operative Imaging can Reduce Negative Appendectomy Rate in Acute Appendicitis.

INTRODUCTION: Acute appendicitis is a common surgical emergency, with a prevalence of 112 per 100,000 people per year in Europe. Negative appendicectomy is defined as a pathologically normal appendix removed from patient suspected with appendicitis. Negative appendectomy rate (NAR) has been reported to be around 15-25%. We aimed to evaluate our unit's negative appendectomy rate and the effect of pre-operative imaging on NAR. METHOD: A retrospective study including all patients who underwent both open and laparoscopic emergency appendicectomy in a single district general hospital from 2017-2018. Clinical information including cost was calculated based on the 2017/18 national tariff payment system. Patients under 18 years old were excluded from this study. RESULTS: Two hundred thirty-two patients were included in this study, of which 69 (29.74%) had a pre-operative CT scan. The mean length of stay was 2.57 days. The sensitivity, specificity, positive predictive value and negative predictive value for CT were 77.8%, 100%, 87.5% and 100%. The negative appendicectomy rate with and without pre-operative CT scan were 7.25% and 22.09% respectively. Based on the 2017/18 national tariff payment system, a CT abdomen and pelvis with contrast and emergency appendicectomy with CC score of 0 cost 92 and 2370 pounds respectively. The total cost of patients who underwent appendicectomy without imaging was £ 322,320. If all patients undergo pre-operative CT, with a reduction of 15% in negative appendicectomy rate, the overall total cost would significantly lower to £ 36,212. CONCLUSION: Our study demonstrated that the negative appendicectomy rate could be improved by preoperative imaging. The study also showed that implementation of preoperative imaging for suspected appendicitis cases could save costs, allowing better allocation of resources.

Cost-effectiveness of Imaging Protocols for Suspected Appendicitis.

BACKGROUND: Inaccurate diagnosis of appendicitis leads to increased costs and morbidity. Ultrasound costs less than computed tomography (CT) or MRI but has lower sensitivity and may not visualize the appendix. METHODS: We conducted a cost-effectiveness analysis using a decision-analytic model of 10 imaging strategies for suspected appendicitis in a hypothetical cohort of patients: no imaging with discharge or surgery; CT only; MRI only; or staged approach with CT or MRI after 1) negative ultrasound result or ultrasound without appendix visualization, 2) ultrasound without appendix visualization, or 3) ultrasound without appendix visualization but with secondary signs of inflammation. Inputs were derived from published literature and secondary data (quality-of-life and cost data). Sensitivity analyses varied risk of appendicitis and proportion of visualized ultrasound. Outcomes were effectiveness (quality-adjusted life-years [QALYs]), total direct medical costs, and cost-effectiveness (cost per QALY gained). RESULTS: The most cost-effective strategy for patients at moderate risk for appendicitis is initial ultrasound, followed by CT if the appendix is not visualized but secondary signs are present (cost of $4815.03; effectiveness of 0.99694 QALYs). Other strategies were well above standard willingness-to-pay thresholds or were more costly and less effective. Cost-effectiveness was sensitive to patients' risk of appendicitis but not the proportion of visualized appendices. CONCLUSIONS: Tailored approaches to imaging based on patients' risk of appendicitis are the most cost-effective. Imaging is not cost-effective in patients with a probability <16% or >95%. For moderate-risk patients, ultrasound without secondary signs of inflammation is sufficient even without appendix visualization.

Evaluation of the diagnostic performance of a decision tree model in suspected acute appendicitis with equivocal preoperative computed tomography findings compared with Alvarado, Eskelinen, and adult appendicitis scores: A STARD compliant article.

This study evaluated the diagnostic performance of a new clinical approach based on decision tree (DT) analysis in adult patients with equivocal computed tomography (CT) findings of acute appendicitis (AA) compared with previous scoring systems.This retrospective study of 244 adult patients with equivocal CT findings included appendicitis (AG, n = 80) and non-appendicitis (NAG, n = 164) groups. The chi-squared automatic interaction detection algorithm was for AA prediction. A receiver operating characteristic curve analysis and area under the curve (AUC) were used to compare the DT analysis with Alvarado, Eskelinen score, and adult appendicitis scores (AAS).The following factors were selected for AA prediction: rebound tenderness severity, migration, urinalysis, symptom duration, leukocytosis, neutrophil count, and C-reactive protein levels. The DT comprised 11 final nodes with the following AA probabilities: node 1, 100% (16/16); node 2, 90% (9/10); node 3, 80% (8/10); node 4, 60.9% (14/23); node 5, 50% (3/6); node 6, 43.8% (7/16); node 7, 22.6% (12/53); node 8, 13% (10/77); node 9, 5.6% (1/18); node 10, 0% (0/12); and node 11, 0% (0/3). The AUC of the DT was higher (0.850 [95% confidence interval {CI}; 0.799-0.893]) than the Alvarado score (0.695 [95% CI; 0.633-0.752]), AAS (0.749 [95% CI; 0.690-0.802]), and the Eskelinen score (0.715 [95% CI; 0.654-0.770]). The results were statistically significant when compared with the AUCs of the Alvarado score, Eskelinen score, and AAS (P < .001, P < .001, P = .003, respectively).The DT-based approach facilitated AA diagnosis and determination of clinical status in patients with equivocal preoperative CT findings and ambiguous results.

Prospective multicentre cohort trial on acute appendicitis and microbiota, aetiology and effects of antimicrobial treatment: study protocol for the MAPPAC (Microbiology APPendicitis ACuta) trial.

INTRODUCTION: Based on the epidemiological and clinical data, acute appendicitis can present either as uncomplicated or complicated. The aetiology of these different appendicitis forms remains unknown. Antibiotic therapy has been shown to be safe, efficient and cost-effective for CT-confirmed uncomplicated acute appendicitis. Despite appendicitis being one of the most common surgical emergencies, there are very few reports on appendicitis aetiology and pathophysiology focusing on the differences between uncomplicated and complicated appendicitis. Microbiology APPendicitis ACuta (MAPPAC) trial aims to evaluate these microbiological and immunological aspects including immune response in the aetiology of these different forms also assessing both antibiotics non-responders and appendicitis recurrence. In addition, MAPPAC aims to determine antibiotic and placebo effects on gut microbiota composition and antimicrobial resistance. METHODS AND ANALYSIS: MAPPAC is a prospective clinical trial with both single-centre and multicentre arm conducted in close synergy with concurrent trials APPendicitis ACuta II (APPAC II) (per oral (p.o.) vs intravenous+p.o. antibiotics, NCT03236961) and APPAC III (double-blind trial placebo vs antibiotics, NCT03234296) randomised clinical trials. Based on the enrolment for these trials, patients with CT-confirmed uncomplicated acute appendicitis are recruited also to the MAPPAC study. In addition to these conservatively treated randomised patients with uncomplicated acute appendicitis, MAPPAC will recruit patients with uncomplicated and complicated appendicitis undergoing appendectomy. Rectal and appendiceal swabs, appendicolith, faecal and serum samples, appendiceal biopsies and clinical data are collected during the hospital stay for microbiological and immunological analyses in both study arms with the longitudinal study arm collecting faecal samples also during follow-up up to 12 months after appendicitis treatment. ETHICS AND DISSEMINATION: This study has been approved by the Ethics Committee of the Hospital District of Southwest Finland (Turku University Hospital, approval number ATMK:142/1800/2016) and the Finnish Medicines Agency. Results of the trial will be published in peer-reviewed journals. TRIAL REGISTRATION NUMBER: NCT03257423.

CT in Differentiating Complicated From Uncomplicated Appendicitis: Presence of Any of 10 CT Features Versus Radiologists' Gestalt Assessment.

OBJECTIVE. The purpose of this study is to propose a sensitive CT criterion (the presence of any of 10 CT features) for complicated appendicitis that could be used in the nonoperative management of appendicitis and to compare the diagnostic performance of this sensitive CT criterion with that of gestalt assessment. MATERIALS AND METHODS. This retrospective study, which was conducted in a tertiary teaching hospital, included 100 patients with suspected appendicitis on CT. Complicated appendicitis, defined as gangrenous or perforated appendicitis, was pathologically or surgically confirmed in 32 patients. Six radiologists independently determined the presence of 10 previously reported CT features of complicated appendicitis (contrast enhancement defect of the appendiceal wall, abscess, extraluminal air, intraluminal air, extraluminal appendicolith, intraluminal appendicolith, moderate-to-severe periappendiceal fat stranding, periappendiceal fluid, ileus, and ascites) and rated the likelihood score for complicated appendicitis using gestalt assessment. The sensitivity and specificity of CT for complicated appendicitis were measured by the presence of any of 10 CT features (the any-of-10-features criterion) and by the radiologists' gestalt assessment. Pooled sensitivity and specificity were compared using a generalized linear mixed model. RESULTS. The pooled sensitivity of the presence of any of 10 CT features was higher than that of gestalt assessment (92% vs 64%; difference, 28% [95% CI, 10-46%]; p < 0.001), although the pooled specificity was lower (43% vs 76%; difference, -33% [95% CI, -48% to -17%]; p < 0.001). CONCLUSION. The pooled sensitivity of the presence of any of 10 CT features was higher than that of gestalt assessment, at the cost of lower specificity. For prudent selection of patients who should receive nonoperative treatment of appendicitis, the any-of-10-features criterion may be used to decrease treatment failure associated with a false-negative diagnosis of complication.