Pediatric Appendicitis Score Research Articles

Pediatric Appendicitis Score（PAS）を用いた小児複雑性虫垂炎の術前診断についての検討

Pediatric Appendicitis Score（PAS）を用いた小児複雑性虫垂炎の術前診断についての検討

Is Ischemia-Modified Albumin a Reliable Marker in Accurate Diagnosis of Appendicitis in Children?

Acute appendicitis is one of the most common abdominal emergencies. Despite all improvements in diagnostic techniques, there are still ongoing problems as proper diagnosis, misdiagnosis and perforated appendicitis. The aim of this study is to demonstrate the clinical value of IMA in patients with appendicitis and to determine the accurate diagnosis of appendicitis in clinically suspected patients. Pediatric patients with acute abdominal pain who had the Pediatric Appendicitis Score (PAS) ≥ 7 (n = 109) and a control group of 35 patients were included in this prospective case-control study. Patients were divided into two groups: patients with appendicitis (pathologically confirmed) (n = 78) and no appendicitis (n = 31). No appendicitis included observation patients and negative appendectomy. Serum samples were collected for routine laboratory parameters and IMA before surgery. Patients with appendicitis had significantly higher IMA levels than no appendicitis and control groups (p = 0.001 and p < 0.001; respectively). Moreover, patients with negative appendectomy had significantly lower IMA levels than patients with appendicitis (p = 0.009). IMA and PAS were used together, and in the ROC analysis, we obtained 0.81 AUC for PAS and 0.89 AUC for PAS and IMA. The current study indicated that IMA is a reliable marker for accurate diagnosis of appendicitis. The combination of IMA with PAS score has been shown to facilitate the diagnosis of appendicitis.

237 The Use of a Carepath in the Diagnosis and Management of Appendicitis in Children in a Large Integrated Health System Reduced Unnecessary Computed Tomography Imaging

Appendicitis is the most common cause of an acute surgical abdomen in children. More than 100,000 children undergo appendectomy annually in the USA. Diagnosis is often challenging as only 1/3 of pediatric patients present with classical symptoms that include right lower quadrant pain, anorexia, and nausea/vomiting. With the increased usage of advanced imaging, diagnostic accuracy has improved. Although Computed Tomography of abdomen/pelvis (CT abd/pelvis) is the most accurate imaging modality, it requires radiation. Recent studies have shown that ultrasound (US) of the appendix in experienced hands can accurately diagnose appendicitis without radiation and with decreased cost. In addition, the pediatric appendicitis score (PAS) has been shown to be an effective tool to identify patients with appendicitis in the pediatric emergency department (ED). A joint CarePath was created by the Departments of Emergency Medicine, Pediatric Hospital Medicine, Radiology and Pediatric Surgery to manage these patients. The CarePath includes placing patients in an initial risk assessment category with PAS (high suspicion, equivocal, low suspicion), followed by US of the appendix (see figure1-2). The CarePath was initiated in November 2018. We planned to compare CT abd/pelvis and negative appendectomy rates one-year pre and one year post CarePath for patients 0-18 years old who presented to 3 pediatric emergency departments with concerns of appendicitis (RLQ pain, N/V, fever). Aim is to reduce CT abd/pelvis rate by 50%, keeping negative appendectomy (surgical pathology is negative for appendicitis) rate <1 %. Retrospective chart review for Quality Improvement project. We preliminarily reviewed the data for ten months between May 2018 and February 2019(six months pre and four months post CarePath). The rate of CT abd/pelvis for appendicitis evaluation was reduced from 39% in the pre-CarePath period to 22 % in the post-CarePath period. There was one negative appendectomy in pre-CarePath period. Although surgical pathology was negative for appendicitis; there was no other diagnosis identified and patient clinically improved after appendectomy. There was one case of negative appendectomy post-CarePath implementation in which the patient was ultimately diagnosed with pelvic inflammatory disease. A CarePath consisting of the PAS and US imaging can reduce the number of CTs performed without resultant increase of missed diagnosis. These preliminary results suggest that a CarePath can reduce variability and enhance patient and provider satisfaction in the management of suspected pediatric appendicitis. Further education of the Pediatric ED and Pediatric Surgery providers needed to sustain and further improve the desired outcomes.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Integration of Physical Examination, Old and New Biomarkers, and Ultrasonography by Using Neural Networks for Pediatric Appendicitis.

The objective of this study was to evaluate physical examinations, imaging, and laboratory analyses individually and combined using innovative statistical analysis methods for the accurate diagnosis of pediatric appendicitis. Patients admitted to hospital with symptoms of abdominal pain whose pediatric appendicitis scores greater than 3 were included in the study. Clinical, radiologic, and laboratory findings and as a new biomarker calprotectin (CPT) concentrations were evaluated individually and combined using artificial neural networks (ANNs), which revealed latent relationships for a definitive diagnosis. Three hundred twenty patients were evaluated (190 appendicitis [43 perforated] vs 130 no appendicitis). The mean ± SD age was 11.3 ± 3.6 years and 63% were male. Pediatric appendicitis scores, white blood cell (WBC) count, absolute neutrophil count (ANC), C-reactive protein (CRP) level, procalcitonin (PCT) and CPT concentrations were higher in the appendicitis group; however, only WBC and ANC were higher in first 24 hours of pain. White blood cells and CRP were diagnostic markers in patients whose appendix could not be visualized using ultrasonography (US). On classic receiver operating characteristic (ROC) analysis, the areas under the curve (AUCs) were not strong enough for differential diagnosis (WBC, 0.73; ANC, 0.72; CRP, 0.65; PCT and CPT, 0.61). However, when the physical examination, US, and laboratory findings were analyzed in a multivariate model and the ROC analysis obtained from the variables with ANN, an ROC curve could be obtained with 0.91 AUC, 89.8% sensitivity, and 81.2% specificity. C-reactive protein and PCT were diagnostic for perforated appendicitis with 0.83 and 0.75 AUC on ROC. Although none of the biomarkers were sufficient for an accurate diagnosis of appendicitis individually, a combination of physical examination and laboratory and US was a good diagnostic tool for pediatric appendicitis.

Анализ результатов применения Pediatric Appendicitis Score в дифференциальной диагностике болей в животе у детей в возрасте 5–17 лет

Анализ результатов применения Pediatric Appendicitis Score в дифференциальной диагностике болей в животе у детей в возрасте 5–17 лет

Validation of the Pediatric Appendicitis Risk Calculator (pARC) in a Community Emergency Department Setting

The pediatric Appendicitis Risk Calculator (pARC) is a validated clinical tool for assessing a child's probability of appendicitis. Our objective was to assess the performance of the pARC in community emergency departments (EDs) and to compare its performance with that of the Pediatric Appendicitis Score (PAS). We conducted a prospective validation study from October 1, 2016, to April 30, 2018, in 11 community EDs serving general populations. Patients aged 5 to 20.9 years and with a chief complaint of abdominal pain and less than or equal to 5 days of right-sided or diffuse abdominal pain were eligible for study enrollment. Our primary outcome was the presence or absence of appendicitis within 7 days of the index visit. We reported performance characteristics and secondary outcomes by pARC risk strata and compared the receiver operator characteristic (ROC) curves of the PAS and pARC. We enrolled 2,089 patients with a mean age of 12.4 years, 46% of whom were male patients. Appendicitis was confirmed in 353 patients (16.9%), of whom 55 (15.6%) had perforated appendixes. Fifty-four percent of patients had very low (<5%) or low (5% to 14%) predicted risk, 43% had intermediate risk (15% to 84%), and 4% had high risk (≥85%). In the very-low- and low-risk groups, 1.4% and 3.0% of patients had appendicitis, respectively. The area under the ROC curve was 0.89 (95% confidence interval 0.87 to 0.92) for the pARC compared with 0.80 (95% confidence interval 0.77 to 0.82) for the PAS. The pARC accurately assessed appendicitis risk for children aged 5 years and older in community EDs and the pARC outperformed the PAS.

Survey of efficacy of pediatric appendicitis score in Iranian patients less than 18 years old referred to the emergency department.

Introduction:Abdominal pain, in particular appendicitis, is a common cause of emergency department visits in children. Therefore, early diagnosis is very important. There are different scoring systems for the diagnosis of appendicitis. This study is the first study to evaluate the performance and accuracy of pediatric appendicitis score (PAS) in Iranian children with abdominal pain in emergency departments.Methods:This is a cross-sectional study of children under 18 years with suspected appendicitis who were referred to the emergency medicine department of hospitals affiliated to SBMU during 2015. Acute appendicitis was determined according to pathological findings, and final PAS scores were calculated for all children. With statistical analysis, comparison between two groups was calculated and the diagnostic accuracy of PAS score was estimated.Results:88 children with mean age of 10.5 ± 3 were studied. According to clinical examination 58 of the children were suspected to have acute appendicitis and 30 others were healthy. In current study, the diagnostic accuracy and precision of PAS at cutoff of 5.5 in patients younger than 18 years admitted to the emergency department with suspected acute appendicitis was 91% and 92%, respectively. Sensitivity, specificity, positive predictive value, and negative predictive value were 93.88%, 86.21% and 92%, 89.29%, respectively.Conclusions:The results of current study showed that PAS has high diagnostic predictive value for the diagnosis of acute appendicitis in children under 18 years and due to the advantages listed for this score, its use is recommended for children in emergencies.

Correlation of the Results of Pediatric appendicitis Score (Pas) with the Results of the Ultrasonography (Usg) Appendix in Children's Appendicitis Patients

Correlation of the Results of Pediatric appendicitis Score (Pas) with the Results of the Ultrasonography (Usg) Appendix in Children's Appendicitis Patients

Ruling out Appendicitis in Children: Can We Use Clinical Prediction Rules?

PurposeTo identify available clinical prediction rules (CPRs) and investigate their ability to rule out appendicitis in children presenting with abdominal pain at the emergency department, and accordingly select CPRs that could be useful in a future prospective cohort study. MethodsA literature search was conducted to identify available CPRs. These were subsequently tested in a historical cohort from a general teaching hospital, comprising all children (< 18 years) that visited the emergency department between 2012 and 2015 with abdominal pain. Data were extracted from the electronic patient files and scores of the identified CPRs were calculated for each patient. The negative likelihood ratios were only calculated for those CPRs that could be calculated for at least 50% of patients. ResultsTwelve CPRs were tested in a cohort of 291 patients, of whom 87 (29.9%) suffered from acute appendicitis. The Ohmann score, Alvarado score, modified Alvarado score, Pediatric Appendicitis score, Low-Risk Appendicitis Rule Refinement, Christian score, and Low Risk Appendicitis Rule had a negative likelihood ratio < 0.1. The Modified Alvarado Scoring System and Lintula score had a negative likelihood ratio > 0.1. Three CPRs were excluded because the score could not be calculated for at least 50% of patients. ConclusionThis study identified seven CPRs that could be used in a prospective cohort study to compare their ability to rule out appendicitis in children and investigate if clinical monitoring and re-evaluation instead of performing additional investigations (i.e., ultrasound) is a safe treatment strategy in case there is low suspicion of appendicitis.

A novel noninvasive appendicitis score with a urine biomarker

PurposeThe aim of our study was to develop an appendicitis score incorporating a urine biomarker, Leucine rich alpha-2-glycoprotein (LRG), for evaluation of children with abdominal pain. MethodsFrom January to August 2017 we prospectively enrolled children aged 4–16 years old admitted for suspected appendicitis. Urine samples for LRG analysis were obtained preoperatively and quantified by enzyme-linked immunosorbent assay (ELISA) after correction for patient hydration status. The diagnosis of appendicitis was based on operative findings and histology. Logistic regression was used to identify prospective predictors. ResultsA total of 148 patients were recruited, of which 42(28.4%) were confirmed appendicitis. Our Appendicitis Urinary Biomarker (AuB) model incorporated urine LRG with 3 clinical predictors: ‘constant pain’, ‘right iliac fossa tenderness’, ‘pain on percussion’. Area under the ROC curve for AuB was 0.82 versus 0.78 for the Pediatric Appendicitis Score (PAS) on the same cohort of patients. A model-calculated risk score of <0.15 is interpreted as low risk of appendicitis. Sensitivity for the AuB at this cutoff was 97.6%, specificity 37.7%, negative predictive value 97.6%, positive predictive value 38.3%, and negative likelihood ratio 0.06. ConclusionThe noninvasive AuB score appears promising as a diagnostic tool for excluding appendicitis in children without the need for blood sampling. Type of studyStudy of diagnostic test. Level of evidenceLevel III.

Retrospective Multivariate Analysis of Data from Children with Suspected Appendicitis: A New Tool for Diagnosis.

Background Decision-making for management may sometimes be difficult in acute appendicitis (AA). Various diagnostic scoring systems exist, but their sensitivity and specificity rates are far from ideal. In this study, the determination of the predictors and the effect of radiological data and developing a new scoring system were aimed. Methods Medical records of patients who were hospitalized for AA between February 2012 and October 2016 were retrospectively reviewed. All data were compared between patients with and without appendicitis. The multivariate analysis was performed to define significant variables and to examine the sensitivity and specificity of each group of predictors including radiological data. A new scoring system (NSS) was formed and was compared with two existing scoring systems: pediatric appendicitis score (PAS) and Alvarado scoring system (ASS) by using reclassification method. Results Negative appendectomy rate was 11.3%. Statistical analysis identified 21 independently significant variables. The heel drop test had the highest odds ratio. Sensitivity and specificity rates of clinical predictors were 84.6% and 94.8%, respectively. Radiological predictors increased the sensitivity rate to 86.9%. Sensitivity and specificity rates for PAS, ASS, and NSS were 86.8% and 83.9%, 84.7% and 81.6%, and 96.8% and 95.6%, respectively. The “re-assessed negative appendectomy rate” was 6.2% and false positive results were remarkably more common in patients with duration of symptoms less than 24 hours. Conclusion Radiological data improves the accuracy of diagnosis. Containing detailed clinical and radiological data, NSS performs superiorly to PAS and ASS, regarding sensitivity and specificity without any age limitation. The efficiency of NSS may be enhanced by determining different predictors for different phases of the inflammatory process.

Determining the utility of the pediatric appendicitis score in a community hospital setting

Purpose: Most studies of the pediatric appendicitis score (PAS) were conducted at academic centers. Therefore prior to applying this score in a quality improvement initiative around the diagnosis of appendicitis, we evaluated the effectiveness of this score in our community hospital setting. Methods: A retrospective chart review evaluated baseline data over a 6 month period of time (1/22/15-7/22/15). Patients ( < 18yo) were identified who presented to one of our 4 ERs with a diagnosis of abdominal pain or appendicitis. Charts were manually reviewed and assigned a PAS based on lab values and medical provider notes. Practitioner concern for appendicitis during the visit (based on notes, …

Determining the utility of the pediatric appendicitis score in a community hospital setting

Determining the utility of the pediatric appendicitis score in a community hospital setting

Development and Validation of a Novel Pediatric Appendicitis Risk Calculator (pARC).

We sought to develop and validate a clinical calculator that can be used to quantify risk for appendicitis on a continuous scale for patients with acute abdominal pain. The pediatric appendicitis risk calculator (pARC) was developed and validated through secondary analyses of 3 distinct cohorts. The derivation sample included visits to 9 pediatric emergency departments between March 2009 and April 2010. The validation sample included visits to a single pediatric emergency department from 2003 to 2004 and 2013 to 2015. Variables evaluated were as follows: age, sex, temperature, nausea and/or vomiting, pain duration, pain location, pain with walking, pain migration, guarding, white blood cell count, and absolute neutrophil count. We used stepwise regression to develop and select the best model. Test performance of the pARC was compared with the Pediatric Appendicitis Score (PAS). The derivation sample included 2423 children, 40% of whom had appendicitis. The validation sample included 1426 children, 35% of whom had appendicitis. The final pARC model included the following variables: sex, age, duration of pain, guarding, pain migration, maximal tenderness in the right-lower quadrant, and absolute neutrophil count. In the validation sample, the pARC exhibited near perfect calibration and a high degree of discrimination (area under the curve: 0.85; 95% confidence interval: 0.83 to 0.87) and outperformed the PAS (area under the curve: 0.77; 95% confidence interval: 0.75 to 0.80). By using the pARC, almost half of patients in the validation cohort could be accurately classified as at <15% risk or ≥85% risk for appendicitis, whereas only 23% would be identified as having a comparable PAS of <3 or >8. In our validation cohort of patients with acute abdominal pain, the pARC accurately quantified risk for appendicitis.

Does the implementation of a pediatric appendicitis pathway promoting ultrasound work outside of a children's hospital?

BackgroundEfficacy of care pathways for pediatric appendicitis is well established in children's hospitals, but not in community Emergency Departments (EDs). Methods: A diagnostic pathway combining the Pediatric Appendicitis Score (PAS) with selective ultrasound was implemented. The charts of 2201 pediatric patients seen at four general EDs before and after implementation were retrospectively reviewed, identifying 611 children seriously considered for appendicitis. ResultsThere were no cases of missed appendicitis within the pathway cohort (0/72). Low-PAS children on pathway had fewer computed tomography (CT) scans (0% vs. 21%; p < 0.02). Moderate-PAS patients also had a reduced CT-first rate (2.4% vs. 23%; p < 0.01). However, pathway adoption in 2016 was only 24%. Correct pathway application would have avoided 58 ultrasounds and 17 CTs over three months (annual savings $281,276). ConclusionA pediatric appendicitis pathway is safe, rules out low suspicion patients without imaging, and is cost effective in a general hospital setting.

Integration of radiology and clinical score in pediatric appendicitis.

The efficacy of ultrasonography (US) and abdominal X-ray in combination with Pediatric Appendicitis Score (PAS) is complicated in the diagnosis of acute appendicitis. Abdominal X-ray is as useful as US with clinical assessment when evaluated by experienced pediatric radiologist in acute appendicitis. The aim of this study was to determine the value of US and abdominal X-ray for appendicitis in children when combined with clinical assessment based on PAS, and to establish a practical pathway for acute appendicitis in childhood. A prospective, observational cohort study was conducted at an urban, academic pediatric emergency department. Patients were classified at low (PAS 1-4), intermediate (PAS 5-7), or high (PAS 8-10) risk for appendicitis. Low-risk patients were discharged with telephone follow-up in ≤10days; those at intermediate risk underwent X-ray and US. High-risk patients received immediate surgical consultation. Patients were grouped on histopathology as having either proven acute appendicitis or no appendicitis. A total of 288 children were analyzed. Surgery was performed in 134 patients (46.5%), and 128 (95.5%) had positive histopathology. Mean PAS in the patients with and without appendicitis was 7.09±1.42 and 4.97±2.29, respectively (P=0.00). The rate of missed cases was 6/288 (2%), and the negative appendectomy rate was 6/134 (4.4%). When the score cut-off was set at 6, the sensitivity and specificity of PAS was 86.7% and 63.1%, respectively. The diagnostic performance of daytime US had a sensitivity of 91.1% and specificity of 71.1%. Also, positive US or PAS >6 or both, had sensitivity and specificity 96.7% and 59.9%, respectively. US or abdominal X-ray in children with possible appendicitis should be integrated with PAS to determine the next steps in management. In the case of discordance between the clinical findings and radiology, prolonged observation or further imaging are recommended.

Correlation of Pediatric Appendicitis Score (Pas) With Appendix Diameter on Children in H. Adam Malik General Hospital Medan and Network Hospital in 2016

Acute appendicitis is one of the most abdominal acute causes that occurs in younger individuals but can also occur in any age range. Children are the most affected age by acute appendicitis. The age that most vulnerable to acute appendicitis is 10-20 years of age (Tian Y et all, 2015). In appendicitis, the severity of inflammation occurring in the appendix determines the severity of symptoms that occur in an individual who experiences it (Zarandiet all, 2014). One of the ways used to establish diagnosis of appendicitis is with PED (Pediatric Appendicitis Score). In a study by Thomas Rettenbacher, the outer diameter of the appendix ≥ 6 mm obtained on ultrasound examination may also indicate an acute appendicitis state with 100% sensitivity and a specificity of 60%. So in this study we analyzed the correlation relationship between the PAS score with the outer diameter of the appendix in the case of appendicitis.

Different Clinical Features and Lower Scores in Clinical Scoring Systems for Appendicitis in Preschool Children: Comparison with School Age Onset.

PurposeTo clarify the clinical features of appendicitis in preschool children and to explore clinical appendicitis scoring systems in this age group.MethodsWe retrospectively collected data on 142 children, aged 10 years or younger, with confirmed diagnosis of appendicitis based on surgical and pathologic findings. Enrolled subjects were divided into two groups: Group 1 (preschool children aged ≤5 years, n=41) and Group 2 (school children aged >5 to ≤10 years, n=101). Data analyzed included clinical presentation, laboratory findings, the pediatric appendicitis score (PAS), and the modified Alvarado score (MAS).ResultsThe most common presenting symptom was abdominal pain in both groups (92.7% vs. 97.0%). Other presenting symptoms were as follows: fever (65.9%), vomiting (68.3%), right lower quadrant (RLQ) localization (24.4%), anorexia (14.6%), and diarrhea (7.3%) in Group 1, and RLQ localization (74.3%), vomiting (71.3%), anorexia (52.5%), fever (47.5%), and diarrhea (11.9%) in Group 2. Perforation and abscess occurred more frequently in Group 1 than in Group 2 (43.9% vs. 12.9%, p<0.001; 34.1% vs. 5.0%, p<0.001; respectively). PAS and MAS were lower in Group 1 than in Group 2 (4.09±1.97 vs. 6.91±1.61, p=0.048; 4.65±1.79 vs. 6.51±1.39, p=0.012; respectively).ConclusionIn preschool children, appendicitis often presents with atypical features, more rapid progression, and higher incidence of complications. This age group is more likely to have lower PAS and MAS than those of school children.

Neutrophil-to-lymphocyte ratio in pediatric acute appendicitis

Background/Aim. Acute appendicitis (AA) is the most frequent emergency and appendectomy is the most frequent abdominal operation in the pediatric surgery. Diagnosis of AA in children is more difficult due to a lack of cooperation and poor clinical history data, leading to significant number of misdiagnostic cases. Our aim was to explore whether neutrophil to lymphocyte ratio (NLR) may be useful in diagnosis and follow-up of AA in children. Methods. Prospective investigation of NLR values in 129 consecutive patients admitted to the Mother and Child Healthcare Institute of Serbia and referred for surgery due to AA was performed. According to the pathohistological findings, patients were divided into 3 groups: normal/early, uncomplicated (phlegmonous) and complicated (gangrenous or/and perforated) AA. Laboratory analysis was done preoperativly and on the 1st and the 3rd postoperative days. Results. Statistically significant differences of NLR values were found in the different time points in total of patients and per groups. Some statistically significant differences of NLR values among histopathological groups were recorded. Investigations of correlation of NLR and other laboratory and clinical parameters showed strong positive correlation between NLR and C-reactive protein postoperatively and between NLR and Pediatric Appendicitis Score (PAS) preoperatively. Strong negative correlation with preoperative symptoms duration (PSD) were also present. Optimal cutoff NLR value between negative and positive appendectomies was 6.14. Conclusion. NLR provides well monitoring of progression of AA in children and, its cutoff values may help in distinguishing the phases of AA. Because of that, NLR should be used in diagnosis of AA in children.

Pediatric appendicitis score in the diagnosis of childhood appendicitis: a validation study

Background: Pediatric appendicitis score (PAS) is a scoring system which includes symptoms, physical examination and laboratory tests in children suspected to have appendicitis. The objectives of this study were to analyze the diagnostic value of Paediatric Appendicitis Score and to aid early diagnosis of appendicitis.Methods: A prospective study was done in a Medical College hospital, in Mangalore in children aged between 4-16 years, admitted during study period June to December 2016, with right Iliac fossa pain, suspected to have appendicitis. Data from the children including demographic details, clinical features, laboratory investigations and ultrasound done were recorded in proformas after consent from parents. The PAS score was applied to them. If PAS was between 4-6, PAS scoring was repeated after 6 hours. Investigations done were noted. If child was taken up for surgery, histopathology report of the biopsy specimen was collected. The decision to operate or manage conservatively was taken up by the treating pediatric surgeon. PAS score was compared with ultrasound and biopsy report.Results: Sixty children were included in the study. Anorexia, emesis, migration pain, cough tenderness and leukocytosis were the features most consistently seen in appendicitis. Initial PAS were comparable to the repeat scores. Ultrasound showed presence of appendicitis in 88.3% of the children. Ultrasound showed appendicitis in all children with PAS ≥7. Twenty-six children out of 60 underwent surgery. Out of 20 children with PAS ≥7.15 (75%) were taken up for surgery and biopsy showed appendicitis. Biopsy was done in 26 children, of whom 58.1% had PAS ≥ 7. These findings were statistically significant. Conclusions: Paediatric appendicitis score is a valuable tool in diagnosing childhood appendicitis.