Profiles of US and CT imaging features with a high probability of appendicitis

Hyperechoic Periappendiceal Fat: Evaluation of Criteria for Improving Specificity in the Sonographic Diagnosis of Appendicitis in Pediatric Patients

OBJECTIVES

To test the hypothesis that abutting and encasing types of hyperechoic periappendiceal fat are specific sonographic indicators of appendicitis in pediatric patients, including individuals with maximum outer diameters (MODs) of 6 to 8 mm in whom diagnosis by the MOD alone is known to be equivocal.

METHODS

Appendiceal sonograms of 271 consecutive pediatric patients were retrospectively evaluated for hyperechoic periappendiceal fat (globular, ≥1.0 cm; categorized as type 0, none; type 1, "abutting," encompassing <180° of the appendiceal circumference; or type 2, "encasing," encompassing 180° or more of the appendiceal circumference) and the MOD. Histopathologic and medical records constituted reference standards. Statistical methods included the binomial distribution, logistic regression, a receiver operating characteristic analysis, and the exact McNemar test.

RESULTS

All patients with hyperechoic fat and 105 of 107 patients with appendicitis had MODs of 6 mm or greater. The MOD and fat types 1 and 2 each were significantly associated with appendicitis in the univariable regression. The MOD and fat type 1 were independently associated with appendicitis in multivariable regression (odds ratio, 24.97; P = .034; and odds ratio, 5.35; P < .001, respectively). Specificities of an MOD of 6 to 8 mm and an MOD of 6 mm or greater alone were 89.0% (95% confidence interval, 83.2%-93.4%); these increased to 100.0% each (95% confidence interval, 97.8%-100.0%; P < .001) when combined with fat types 1, 2, and either 1 or 2 as diagnostic criteria, with positive predictive values of 100.0%.

CONCLUSIONS

Types 1 and 2 periappendiceal fat are specific indicators of appendicitis, and both improve specificity compared to the MOD. Importantly, they add specificity in diagnosing appendicitis in patients with diagnostically equivocal MODs of 6 to 8 mm.

Computed tomography for diagnosis of acute appendicitis in adults

BACKGROUND

Diagnosing acute appendicitis (appendicitis) based on clinical evaluation, blood testing, and urinalysis can be difficult. Therefore, in persons with suspected appendicitis, abdominopelvic computed tomography (CT) is often used as an add-on test following the initial evaluation to reduce remaining diagnostic uncertainty. The aim of using CT is to assist the clinician in discriminating between persons who need surgery with appendicectomy and persons who do not.

OBJECTIVES

Primary objective Our primary objective was to evaluate the accuracy of CT for diagnosing appendicitis in adults with suspected appendicitis. Secondary objectives Our secondary objectives were to compare the accuracy of contrast-enhanced versus non-contrast-enhanced CT, to compare the accuracy of low-dose versus standard-dose CT, and to explore the influence of CT-scanner generation, radiologist experience, degree of clinical suspicion of appendicitis, and aspects of methodological quality on diagnostic accuracy.

SEARCH METHODS

We searched MEDLINE, Embase, and Science Citation Index until 16 June 2017. We also searched references lists. We did not exclude studies on the basis of language or publication status.

SELECTION CRITERIA

We included prospective studies that compared results of CT versus outcomes of a reference standard in adults (> 14 years of age) with suspected appendicitis. We excluded studies recruiting only pregnant women; studies in persons with abdominal pain at any location and with no particular suspicion of appendicitis; studies in which all participants had undergone ultrasonography (US) before CT and the decision to perform CT depended on the US outcome; studies using a case-control design; studies with fewer than 10 participants; and studies that did not report the numbers of true-positives, false-positives, false-negatives, and true-negatives. Two review authors independently screened and selected studies for inclusion.

DATA COLLECTION AND ANALYSIS

Two review authors independently collected the data from each study and evaluated methodological quality according to the Quality Assessment of Studies of Diagnostic Accuracy - Revised (QUADAS-2) tool. We used the bivariate random-effects model to obtain summary estimates of sensitivity and specificity.

MAIN RESULTS

We identified 64 studies including 71 separate study populations with a total of 10,280 participants (4583 with and 5697 without acute appendicitis). Estimates of sensitivity ranged from 0.72 to 1.0 and estimates of specificity ranged from 0.5 to 1.0 across the 71 study populations. Summary sensitivity was 0.95 (95% confidence interval (CI) 0.93 to 0.96), and summary specificity was 0.94 (95% CI 0.92 to 0.95). At the median prevalence of appendicitis (0.43), the probability of having appendicitis following a positive CT result was 0.92 (95% CI 0.90 to 0.94), and the probability of having appendicitis following a negative CT result was 0.04 (95% CI 0.03 to 0.05). In subgroup analyses according to contrast enhancement, summary sensitivity was higher for CT with intravenous contrast (0.96, 95% CI 0.92 to 0.98), CT with rectal contrast (0.97, 95% CI 0.93 to 0.99), and CT with intravenous and oral contrast enhancement (0.96, 95% CI 0.93 to 0.98) than for unenhanced CT (0.91, 95% CI 0.87 to 0.93). Summary sensitivity of CT with oral contrast enhancement (0.89, 95% CI 0.81 to 0.94) and unenhanced CT was similar. Results show practically no differences in summary specificity, which varied from 0.93 (95% CI 0.90 to 0.95) to 0.95 (95% CI 0.90 to 0.98) between subgroups. Summary sensitivity for low-dose CT (0.94, 95% 0.90 to 0.97) was similar to summary sensitivity for standard-dose or unspecified-dose CT (0.95, 95% 0.93 to 0.96); summary specificity did not differ between low-dose and standard-dose or unspecified-dose CT. No studies had high methodological quality as evaluated by the QUADAS-2 tool. Major methodological problems were poor reference standards and partial verification primarily due to inadequate and incomplete follow-up in persons who did not have surgery.

AUTHORS' CONCLUSIONS

The sensitivity and specificity of CT for diagnosing appendicitis in adults are high. Unenhanced standard-dose CT appears to have lower sensitivity than standard-dose CT with intravenous, rectal, or oral and intravenous contrast enhancement. Use of different types of contrast enhancement or no enhancement does not appear to affect specificity. Differences in sensitivity and specificity between low-dose and standard-dose CT appear to be negligible. The results of this review should be interpreted with caution for two reasons. First, these results are based on studies of low methodological quality. Second, the comparisons between types of contrast enhancement and radiation dose may be unreliable because they are based on indirect comparisons that may be confounded by other factors.

Variations and morphometric features of the vermiform appendix: A systematic review and meta-analysis of 114,080 subjects with clinical implications

Determining the true and indisputable data regarding the vermiform appendix (VA) morphology is of a great clinical interest. The aim of this study was to provide the best evidence-based anatomical overview of the variations in location and size of VA using a systematic and meta-analytical approach. A systematic review with meta-analysis was performed of studies reporting variants of the location and morphometric data regarding the VA. The MEDLINE/PubMed, ScienceDirect, EMBASE, BIOSIS, SciELO, and Web of Science databases were thoroughly searched throughout June 2018. The reported locations of the body of the VA were re-classified into a new, standardized classification system divided into nine categories. The AQUA tool was used to assess the quality of included studies. The research was conducted following PRISMA guidelines and registered at PROPSERO database. Our meta-analysis included 242 studies (n = 114,080). Overall, the VA was most commonly found in the retrocecal location (32.1%, 95%CI: 29.2-35.1), followed by the pelvic (28.5%, 95%CI: 26.7-30.4) and ileal (14.5%, 95%CI: 11.8-17.7) locations. Subjects without known appendiceal pathologies had significantly smaller VA outer diameters (5.84 mm, 95%CI: 5.68-5.99) than patients diagnosed with acute appendicitis (10.64 mm, 95%CI: 10.14-11.15). The overall pooled mean length of the VA was 80.29 mm (95%CI: 76.68-83.89). Significant differences were found in size of the VA between imaging modalities. The results obtained from this evidence-based anatomy study will improve the clinical understanding of the VA anatomy, which in turn will have major implications for clinical practice. Clin. Anat. 32:85-98, 2019. © 2019 Wiley Periodicals, Inc.

How to differentiate acute pelvic inflammatory disease from acute appendicitis ? A decision tree based on CT findings

PURPOSE

To construct a decision tree based on CT findings to differentiate acute pelvic inflammatory disease (PID) from acute appendicitis (AA) in women with lower abdominal pain and inflammatory syndrome.

MATERIALS AND METHODS

This retrospective study was approved by our institutional review board and informed consent was waived. Contrast-enhanced CT studies of 109 women with acute PID and 218 age-matched women with AA were retrospectively and independently reviewed by two radiologists to identify CT findings predictive of PID or AA. Surgical and laboratory data were used for the PID and AA reference standard. Appropriate tests were performed to compare PID and AA and a CT decision tree using the classification and regression tree (CART) algorithm was generated.

RESULTS

The median patient age was 28 years (interquartile range, 22-39 years). According to the decision tree, an appendiceal diameter ≥ 7 mm was the most discriminating criterion for differentiating acute PID and AA, followed by a left tubal diameter ≥ 10 mm, with a global accuracy of 98.2 % (95 % CI: 96-99.4).

CONCLUSION

Appendiceal diameter and left tubal thickening are the most discriminating CT criteria for differentiating acute PID from AA.

KEY POINTS

• Appendiceal diameter and marked left tubal thickening allow differentiating PID from AA. • PID should be considered if appendiceal diameter is < 7 mm. • Marked left tubal diameter indicates PID rather than AA when enlarged appendix. • No pathological CT findings were identified in 5 % of PID patients.

Predictive factors and outcomes of negative appendectomy

BACKGROUND

The aim of this study was to assess predictive factors for negative appendectomy and to evaluate the outcomes of negative appendectomy.

METHODS

A retrospective chart review of 4,878 patients who underwent appendectomy at our institution from January 2008 to December 2014 was performed.

RESULTS

Younger age (≤15 years), normal white blood cell count, appendix diameter of less than 6 mm on computed tomography (CT), and CT grade less than 3 were found to be independent predictive factors for negative appendectomy. When complications were investigated according to the results of pathologic diagnosis, negative appendectomy had more complications than appendectomy for nonperforated appendicitis, and this was statistically significant.

CONCLUSIONS

When CT findings are equivocal, in deciding to operate for acute appendicitis, additional ultrasonography can be performed. Furthermore, if the patient is younger than 15 years and the white blood cell count is normal, it is recommended to monitor changes in symptoms a little longer rather than operating hastily.

Application of scoring systems with point-of-care ultrasonography for bedside diagnosis of appendicitis

BACKGROUND

Appendicitis is a common disease requiring surgery. Bedside ultrasound (BUS) is a core technique for emergency medicine (EM). The Alvarado score is a well-studied diagnostic tool for appendicitis. This study aimed to investigate the relationship between patients' symptoms, Alvarado score and ultrasound (US) findings, as performed by emergency physicians (EPs) and radiologists, of patients with suspected appendicitis.

METHODS

Three EM specialists underwent the BUS course and core course for appendicitis assessment. Patients suspected of having appendicitis were selected and their Alvarado and modified (m) Alvarado scores calculated. The specialists performed the BUS. Then, patients were given a formal US and surgery consultation if necessary. Preliminary diagnoses, admission or discharge from the emergency department (ED) and final diagnosis were documented. The patients were also followed up after discharge from the hospital.

RESULTS

The determined cut-off value was 2 for Alvarado and 3 for mAlvarado scores. The sensitivities of the two scores were 100%. Each score was used to rule out appendicitis. The results of EP-performed BUS were as follows: accuracy 70%, sensitivity 0.733, specificity 0.673, + LR 2.24, and - LR 0.40 (95%CI). Radiologists were better than EPs at diagnosing appendicitis and radiologists and EPs were equally strong at ruling out appendicitis by US. When US was combined with Alvarado and mAlvarado scores, EP US+Alvarado/mAlvarado scores <3 and radiology US+Alvarado/mAlvarado scores <4 perfectly ruled out appendicitis.

CONCLUSION

BUS performed by EPs is moderately useful in detecting appendicitis. Combined with scoring systems, BUS may be a perfect tool for ruling out decisions in EDs.

Use of Clinical Data to Predict Appendicitis in Patients with Equivocal US Findings

Purpose To determine the incremental value of clinical data in patients with ultrasonographic (US) examinations that were interpreted as being equivocal for acute appendicitis. Materials and Methods Institutional review board approval, with a waiver of informed consent, was obtained for this analysis of clinical and imaging data in patients younger than 18 years old who were evaluated for acute appendicitis. Findings from US examinations were reported in a structured fashion, including two possible equivocal impressions. Clinical data were captured as Pediatric Appendicitis (PAS) or Alvarado scores and considered as categoric (high, intermediate, or low likelihood) and continuous variables to simulate stratification of equivocal US examinations to predict appendicitis. Receiver operating characteristic curves were used to define score cutoffs, and logistic regression was used to assess individual clinical variables as predictors of appendicitis. Results The study population was made up of 776 patients (mean age, 11.7 years ± 3.7), with 429 (55.2%) girls. A total of 203 (26%) patients had appendicitis. US had a negative predictive value of 96.2% and a positive predictive value of 93.3% for depicting appendicitis, with 89 of 782 (11.4%) equivocal examinations. Categoric PAS and Alvarado scores were equivocal for 59.5% (53 of 89) and 50.6% (45 of 89) of equivocal US examinations, respectively. Categoric low- and high-likelihood PAS and Alvarado scores correctly predicted the presence of appendicitis in 61.1% (22 of 36) and 77.3% (34 of 44) of equivocal US examinations, respectively. As continuous variables, a PAS or Alvarado score of 5 or lower could be used to exclude appendicitis, with a 80.8% (21 of 26) and 90% (18 of 20) negative predictive value, respectively. Conclusion The study confirms the excellent performance of US for depicting pediatric appendicitis. In the subset of equivocal US examinations, a low clinical score (≤5) may be used to identify patients with a low likelihood of having appendicitis. (©) RSNA, 2016.

Intra-Appendiceal Air at CT: Is It a Useful or a Confusing Sign for the Diagnosis of Acute Appendicitis?

Objective

To investigate the significance of intra-appendiceal air at CT for the evaluation of appendicitis.

Materials and Methods

We retrospectively analyzed 458 patients (216 men, 242 women; age range, 18-91 years) who underwent CT for suspected appendicitis. Two independent readers reviewed the CT. Prevalence, amount, and appearance of intra-appendiceal air were assessed and compared between the patients with and without appendicitis. Performance of CT diagnosis was evaluated in two reading strategies: once ignoring appendiceal air (strategy 1), and the other time considering presence of appendiceal air as indicative of no appendicitis in otherwise indeterminate cases (strategy 2), using receiver operating characteristic (ROC) analysis.

Results

Of the 458 patients, 102 had confirmed appendicitis. The prevalence of intra-appendiceal air was significantly different between patients with (13.2%) and without (79.8%) appendicitis (p < 0.001). The amount of appendiceal air was significantly lesser in patients having appendicitis as compared with the normal group, for both reader 1 (p = 0.011) and reader 2 (p = 0.002). Stool-like appearance and air-fluid levels were more common in the appendicitis group than in the normal appendix for both readers (p < 0.05). Areas under the ROC curves were not significantly different between strategies 1 and 2 in reader 1 (0.971 vs. 0.985, respectively; p = 0.056), but showed a small difference in reader 2 (0.969 vs. 0.986, respectively; p = 0.042).

Conclusion

Although significant differences were seen in the prevalence, amount, and appearance of intra-appendiceal air between patients with and without appendicitis, it has a limited incremental value for the diagnosis of acute appendicitis.

Diagnostic Imaging of Appendicitis With Supplementation by Transabdominal and Transvaginal Sonography

Acute appendicitis is a condition that can affect any member of the population. Without timely treatment there is a high likelihood of rupture leading to peritonitis, and early diagnosis is imperative to obtaining treatment. Sonography can be used without fear of radiation exposure to the patient and with relatively little discomfort, ideal for pediatric patients. It can also be used with little patient preparation, with the possibility of a more rapid diagnosis than other imaging modalities. For patients presenting with atypical symptoms, sonography may be used to increase diagnostic accuracy, which will lead to a drop in the surgical removal rate of a healthy appendix. When diagnostic criteria are met, sonography results can be correlated with the patient’s blood test and clinical symptoms to make a positive diagnosis. The addition of the transvaginal approach for female patients has further increased the rate of success of diagnosing acute appendicitis, so that appropriate emergent surgery can be done.

Admission levels of serum amyloid a and procalcitonin are more predictive of the diagnosis of acute appendicitis compared with C-reactive protein

BACKGROUND

Acute appendicitis is the commonest surgical emergency, but its diagnosis can be elusive with a negative appendicectomy rate of 20%. The aims of this study were to investigate the potential value of the markers of acute inflammation, serum amyloid A (SAA), and serum procalcitonin (ProCT), in the diagnosis of acute appendicitis in adults and to compare that with the commonly used serum C-reactive protein (CRP).

METHODS

Adult patients presenting with acute right lower abdominal pain and a clinical suspicion of acute appendicitis were included. Blood samples were obtained within 6 hours of admission for rapid serum CRP assay and for end-of-recruitment batch analysis of SAA and serum ProCT concentrations.

RESULTS

A total of 147 patients (81 males) with a mean (±SD) age of 36 (±17) years were recruited. Appendicitis was confirmed histologically in 61 of 72 patients (84.7%) who underwent appendicectomy. A post hoc analysis revealed a diagnostic sensitivity and specificity for SAA of 92% and 72%, ProCT of 85% and 74%, and CRP of 75% and 72%, respectively. The receiver operator characteristics for the area under the curves showed that SAA (P=0.011) and ProCT (P=0.037) significantly exceeded CRP in the prediction of acute appendicitis on admission.

CONCLUSIONS

The measurement of SAA and serum ProCT on admission in patients with clinically suspected acute appendicitis seems to outperform serum CRP in aiding that diagnosis.

A novel reporting system to improve accuracy in appendicitis imaging

OBJECTIVE

The purpose of this study was to ascertain if standardized radiologic reporting for appendicitis imaging increases diagnostic accuracy.

MATERIALS AND METHODS

We developed a standardized appendicitis reporting system that includes objective imaging findings common in appendicitis and a certainty score ranging from 1 (definitely not appendicitis) through 5 (definitely appendicitis). Four radiologists retrospectively reviewed the preoperative CT scans of 96 appendectomy patients using our reporting system. The presence of appendicitis-specific imaging findings and certainty scores were compared with final pathology. These comparisons were summarized using odds ratios (ORs) and the AUC.

RESULTS

The appendix was visualized on CT in 89 patients, of whom 71 (80%) had pathologically proven appendicitis. Imaging findings associated with appendicitis included appendiceal diameter (odds ratio [OR] = 14 [> 10 vs < 6 mm]; p = 0.002), periappendiceal fat stranding (OR = 8.9; p < 0.001), and appendiceal mucosal hyperenhancement (OR = 8.7; p < 0.001). Of 35 patients whose initial clinical findings were reported as indeterminate, 28 (80%) had appendicitis. In this initially indeterminate group, using the standardized reporting system, radiologists assigned higher certainty scores (4 or 5) in 21 of the 28 patients with appendicitis (75%) and lower scores (1 or 2) in five of the seven patients without appendicitis (71%) (AUC = 0.90; p = 0.001).

CONCLUSION

Standardized reporting and grading of objective imaging findings correlated well with postoperative pathology and may decrease the number of CT findings reported as indeterminate for appendicitis. Prospective evaluation of this reporting system on a cohort of patients with clinically suspected appendicitis is currently under way.

Improvement in diagnostic accuracy of ultrasound of the pediatric appendix through the use of equivocal interpretive categories

OBJECTIVE

The purpose of this article is to evaluate the diagnostic performance of ultrasound of the pediatric appendix using standardized structured reports that incorporate equivocal interpretive categories.

MATERIALS AND METHODS

Standardized structured appendix ultrasound reports using a five-category interpretive scheme were reviewed. Interpretive categories were positive, intermediate likelihood, or negative when the appendix was visualized, and secondary signs or no secondary signs when the appendix was not visualized. Interpretations were compared with clinical and pathologic follow-up. Diagnostic accuracy was compared with the accuracy of a simulated binary interpretive scheme based on the same data.

RESULTS

One thousand three hundred fifty-seven examinations were included, with appendicitis present in 16.9% (230/1357) of cases. The appendix was visualized in 47.2% (641/1357) of cases, with interpretations as follows: positive, 27.5% (176/641); intermediate likelihood, 9.7% (62/641); and normal, 62.9% (403/641). The appendicitis rate in each group was 92.6% (163/176), 25.8% (16/62), and 0.5% (2/403), respectively. The appendix was not visualized in 52.8% (716/1357) of cases, with secondary findings identified in 8.5% (61/716) and no secondary findings in 91.5% (655/716) of cases. The appendicitis rate was 39.3% (24/61) and 3.8% (25/655) in these groups, respectively. Appendicitis was present in 32.5% of equivocal (intermediate likelihood and not visualized, secondary findings) cases and 2.6% of negative (normal and not visualized, no secondary findings) cases. Diagnostic accuracy of a five-category scheme was 96.8% versus 94.1% for a binary scheme.

CONCLUSION

Appendix ultrasound examinations interpreted according to a scheme that incorporates equivocal categories better convey diagnostic certainty and increase diagnostic accuracy compared with a binary interpretive scheme.

Appendiceal diameter as a predictor of appendicitis in children: improved diagnosis with three diagnostic categories derived from a logistic predictive model

OBJECTIVES

To develop and assess the performance of a diameter-based logistic predictive model and a derived 3-category interpretive scheme for the sonographic diagnosis of paediatric appendicitis.

METHODS

Appendiceal diameters were extracted from reports of ultrasound examinations in children and young adults. Data were used to generate a logistic predictive model which was used to define negative, equivocal and positive interpretive categories. Diagnostic performance of the derived 3-category interpretive scheme was compared with simulated binary interpretive schemes.

RESULTS

Six hundred forty-one appendix ultrasound reports were reviewed with appendicitis present in 181 (28.2 %). Cut-off diameters based on the logistic predictive model were ≤6 mm = normal, >6 mm-8 mm = equivocal and >8 mm = positive with appendicitis present in 2.6 % (11/428), 64.9 % (72/111) and 96.1 % (98/102) of cases in each group. These cut-offs conferred 97.2 % accuracy with 17.3 % (111/641) of cases considered equivocal. Of the binary cut-offs, a 6 mm cut-off performed best with 91.6 % accuracy. AIC analysis favoured the logistic model over the binary model for prediction of appendicitis.

CONCLUSIONS

A 3-category interpretive scheme based on a logistic predictive model provides higher accuracy in the diagnosis of appendicitis than traditional binary diameter cut-offs. Inclusion of an equivocal interpretive category more accurately reflects the probability distribution of prediction of appendicitis by ultrasound.

KEY POINTS

• Three diameter categories outperform a 6-mm cut-off to diagnose appendicitis • Three categories allow more confident exclusion of appendicitis • Three categories allow more confident diagnosis of appendicitis • Three categories more accurately reflect the probability of appendicitis by ultrasound.

Comparative study between patients with acute appendicitis treated in primary care units and in emergency hospitals

OBJECTIVE

To retrospectively analyze the relationship of time of care, combined with possible post-appendectomy complications, with the promptness of transfer of patients seen in Emergency Care Units (UPA) to the emergency hospital.

METHODS

We analyzed patients with preoperative diagnosis of acute appendicitis undergoing appendectomy from January to July 2012. Patients were divided into two groups according to the site of the first care. Group A included patients who received initial care directly in the emergency department of the Lourenço Jorge County Hospital (HMLJ) and group B consisted of patients seen in the UPA and forwarded to HMLJ to undergo surgical treatment.

RESULTS

the average time between initial treatment and surgery in group A was 29 hours (SD = 21.95) and 54 hours in group B (SD = 54.5). Considering the onset of symptoms, the patients in group A were operated on average 67 hours after (SD = 42.55), while group B, 90 hours (SD = 59.58). After the operation, patients in group A were hospitalized, on average, for 94 hours (SD = 73.53) and group B, 129 hours (SD = 193.42).

CONCLUSION

there was no significant difference in the time elapsed between the onset of symptoms, initial treatment and early surgical treatment, or time elapsed between surgery and discharge.

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

Introduction

Appendicitis is a common condition presenting to the emergency department (ED). Increasingly emergency physicians (EP) are using bedside ultrasound (BUS) as an adjunct diagnostic tool. Our objective is to investigate the test characteristics of BUS for the diagnosis of appendicitis and identify components of routine ED workup and BUS associated with the presence of appendicitis.

Methods

Patients four years of age and older presenting to the ED with suspected appendicitis were eligible for enrollment. After informed consent was obtained, BUS was performed on the subjects by trained EPs who had undergone a minimum of one-hour didactic training on the use of BUS to diagnose appendicitis. They then recorded elements of clinical history, physical examination, white blood cell count (WBC) with polymophonuclear percentage (PMN), and BUS findings on a data form. We ascertained subject outcomes by a combination of medical record review and telephone follow-up.

Results

A total of 125 subjects consented for the study, and 116 had adequate image data for final analysis. Prevalence of appendicitis was 40%. Mean age of the subjects was 20.2 years, and 51% were male. BUS was 100% sensitive (95% CI 87–100%) and 32% specific (95% CI 14–57%) for detection of appendicitis, with a positive predictive value of 72% (95% CI 56–84%), and a negative predictive value of 100% (95% CI 52–100%). Assuming all non-diagnostic studies were negative would yield a sensitivity of 72% and specificity of 81%. Subjects with appendicitis had a significantly higher occurrence of anorexia, nausea, vomiting, and a higher WBC and PMN count when compared to those without appendicitis. Their BUS studies were significantly more likely to result in visualization of the appendix, appendix diameter >6mm, appendix wall thickness >2mm, periappendiceal fluid, visualization of the appendix tip, and sonographic Mcburney’s sign (p<0.05). In subjects with diagnostic BUS studies, WBC, PMN, visualization of appendix, appendix diameter >6mm, appendix wall thickness >2mm, periappendiceal fluid were found to be predictors of appendicitis on logistic regression.

Conclusion

BUS is moderately useful for appendicitis diagnosis. We also identified several components in routine ED workup and BUS that are associated with appendicitis generating hypothesis for future studies.

Improvement in the diagnosis of appendicitis

Our attempts to systematically improve accuracy in the evaluation of patients with suspected appendicitis are, in some ways, hindered by the fact that the condition is so frequently straightforward to diagnose. Careful history-taking and physical examination are reliable in most patients. However, establishing the diagnosis with these skills alone remains vulnerable to conditions that masquerade as acute appendicitis. A substantial body of clinical research over the last quarter-century has shown that improved accuracy is possible. Strategies for improvement include the use of diagnostic scoring systems, laboratory makers such as CRP, diagnostic laparoscopy, and advanced imaging modalities such as CT, MRI, and US. How clinicians use these strategies depends on many factors related to practice setting, the population served, and clinical goals. In children, for instance, the desire to limit exposure to ionizing radiation competes with the greater anatomic detail that a CT scan can provide; at the same time, many hospitals that treat children do not have the resources to maintain the sort of full-time, highly sophisticated abdominal US programs that achieve the highest rates of diagnostic accuracy in clinical studies. Trade-offs have to be made, but improvement is possible in almost all groups of patients: the clinical community should no longer settle for a 15% NA rate when 5% is clearly possible without adverse consequences. Many clinicians will be faced with the task of evaluating patients suspected of having acute appendicitis. A deliberate, proactive, and, ideally, benchmarked strategy for improving diagnosis should be the standard to which we hold ourselves and the promise we deliver to our patients.

Effect of surgeon's judgement on the diagnosis of acute appendicitis

OBJECTIVE

The accuracy of a surgeon's judgement still remains to be controversial in the diagnosis of acute appendicitis, which is a diagnosis usually based on laboratory data and imaging tests.

MATERIAL AND METHODS

Patients with a possible diagnosis of acute appendicitis were reviewed retrospectively with regard to demographic variables, laboratory and imaging results, and treatment modalities.

RESULTS

There were 128 patients with a mean age of 31.2±14 years. The mean white blood cell count and the proportion of polymorphonuclear leukocytes were 11403±4669/mm(3) and 75±11%, respectively. Appendectomy was performed on 66 (51.6%) patients. Conservative management was applied to 62 (48.4%) patients. Statistical analysis showed that patients with appendicitis have a higher white blood cell count (p=0.015) and a higher proportion of polymorphonuclear leukocytes (p=0.023). Sensitivity, specificity and accuracy rates were 84.6%, 63.7% and 74.3% for ultrasound and 100%, 86.7% and 92.2% for computed tomography, respectively.

CONCLUSION

Diagnosis based on patients' laboratory and imaging data, in combination with, the surgeon's judgement appears to yield the best outcomes in patients with suspicion of acute appendicitis.

MRI features associated with acute appendicitis

OBJECTIVES

To identify MRI features associated with appendicitis.

METHODS

Features expected to be associated with appendicitis were recorded in consensus by two expert radiologists on 223 abdominal MRIs in patients with suspected appendicitis. Nine MRI features were studied: appendix diameter >7 mm, appendicolith, peri-appendiceal fat infiltration, peri-appendiceal fluid, absence of gas in the appendix, appendiceal wall destruction, restricted diffusion of the appendiceal wall, lumen or focal fluid collections. Appendicitis was assigned as the final diagnosis in 117/223 patients. Associations between imaging features and appendicitis were evaluated with logistic regression analysis.

RESULTS

All investigated features were significantly associated with appendicitis in univariate analysis. Combinations of two and three features were associated with a probability of appendicitis of 88 % and 92 %, respectively. In patients without any of the nine features, appendicitis was present in 2 % of cases. After multivariate analysis, only an appendix diameter >7 mm, peri-appendiceal fat infiltration and restricted diffusion of the appendiceal wall were significantly associated with appendicitis. The probability of appendicitis was 96 % in their presence and 2 % in their absence.

CONCLUSIONS

An appendix diameter >7 mm, peri-appendiceal fat infiltration and restricted diffusion of the appendiceal wall have the strongest association with appendicitis on MRI.

KEY POINTS

• An enlarged appendix, fat infiltration and restricted diffusion are associated with appendicitis. • One such feature on MRI gives an 88 % probability of appendicitis. • Two features in combination give a probability of appendicitis of 94 %. • Combinations of three features give a probability of appendicitis of 96 %. • The absence of these features almost rules out appendicitis (2 %).

Appendiceal length as an independent risk factor for acute appendicitis

OBJECTIVES

To determine if appendiceal lengths differ between adults with acute appendicitis and asymptomatic controls.

METHODS

In vivo appendiceal length at computed tomography (CT) in 321 adults with surgically proven appendicitis was compared with that in 321 consecutive asymptomatic adult controls. CT length was derived using curved multiplanar reformats along the long axis. Gross pathological length provided external validation for appendectomy cases.

RESULTS

Appendiceal length at CT correlated well with appendicitis specimens (mean length, 6.8 cm vs 6.6 cm; 79 % within 1.5 cm). For asymptomatic controls, mean CT appendiceal length was 7.9 cm, longer in men (8.4 ± 3.8 vs 7.4 ± 3.1 cm; P = 0.02), matching closely historical normative post-mortem data. The mean and standard deviation of appendiceal length at CT were significantly greater among negative controls than in the positive appendicitis group (7.9 ± 3.5 vs 6.8 ± 1.9 cm; P = 0.03). Of appendicitis cases, 90 % (288/321) fell within the range 4.0-10.0 cm, compared with 59 % (189/321) of negative controls (P < 0.001). Among controls, a fivefold increase in appendixes >10 cm and a twofold increase in appendixes <4 cm were observed. Half (9/18) of long appendicitis cases showed tip appendicitis at CT.

CONCLUSIONS

"Intermediate" appendiceal lengths (4-10 cm) are more frequently complicated by acute appendicitis, whereas both "long" (>10 cm) and "short" (<4 cm) lengths are more frequently observed in unaffected adults.

Reevaluating the sonographic criteria for acute appendicitis in children: a review of the literature and a retrospective analysis of 246 cases

RATIONALE AND OBJECTIVES

There has been little rigorous evaluation of the sonographic criteria for acute appendicitis in children. Our clinical experience has called the traditional diagnostic criteria into question. We set out to review the literature, evaluate the most commonly applied diagnostic criteria for acute appendicitis, and identify those criteria that best predict the presence of disease.

MATERIALS AND METHODS

A critical review of the literature concerning the sonographic diagnosis of acute appendicitis was performed. Based on diagnostic criteria identified in that review, two independent, blinded pediatric radiologists retrospectively reviewed 246 right lower quadrant ultrasound examinations in which the appendix was identified with attention to commonly described diagnostic criteria for acute appendicitis. Multivariate and classification and regression tree analysis were performed to identify criteria that predict appendicitis.

RESULTS

In a multivariate analysis, inflammation of the periappendiceal fat is the only finding that statistically significantly predicts acute appendicitis (OR = 68.93, P < .0001). Other criteria such as diameter, noncompressibility, hyperemia, the presence of an appendicolith, and loss of stratification of the appendiceal wall do not independently predict appendicitis.

CONCLUSION

Periappendiceal fat infiltration is the most important diagnostic criterion for acute appendicitis in children. Strict application of other criteria such as diameter should be avoided.

Alternative diagnoses to suspected appendicitis at CT

PURPOSE

To assess alternative diagnoses in adults undergoing computed tomography (CT) for suspected acute appendicitis in routine clinical practice.

MATERIALS AND METHODS

This retrospective study was HIPAA compliant and institutional review board approved; informed consent was waived. A total of 1571 consecutive adults were referred from emergency department or urgent care settings for evaluation of suspected acute appendicitis at a single academic medical center from January 2006 to December 2009. Diagnoses given by board-certified radiologists at nonfocused abdominopelvic CT and ultimate clinical diagnoses by a combination of clinical, surgical, pathologic, and other radiologic findings were analyzed. Comparisons were made by using the Fisher exact test and Mann-Whitney test, where appropriate, with a two-tailed P value of less than .05 used as the criterion for statistical significance.

RESULTS

A specific diagnosis at CT examination was made in 867 of 1571 (55.2%) patients. Acute appendicitis was favored in 371 of 1571 (23.6%) patients. An alternative diagnosis other than appendicitis was suggested in 496 of 1571 (31.6%) patients. Among patients with an alternative CT diagnosis, 204 of 496 (41.1%) were hospitalized and 109 of 496 (22.0%) underwent surgical or image-guided intervention for diagnoses other than appendicitis, compared with rates of 14.1% and 4.4%, respectively, among patients in whom a specific diagnosis was not made at CT (P < .0001). The most common broad categories of disease included nonappendiceal gastrointestinal conditions (46.0%), gynecologic conditions (21.6%), genitourinary conditions (16.9%), and hepatopancreaticobiliary conditions (7.7%).

CONCLUSION

In adult patients clinically suspected of having acute appendicitis, abdominopelvic CT frequently identifies an alternative cause for symptoms, which often requires hospitalization and surgery for treatment.

A critical evaluation of US for the diagnosis of pediatric acute appendicitis in a real-life setting: how can we improve the diagnostic value of sonography?

BACKGROUND

We have observed that day-to-day use of US for acute appendicitis does not perform as well as described in the literature.

OBJECTIVE

Review the diagnostic performance of US in acute appendicitis with attention to factors that influence performance.

MATERIALS AND METHODS

Retrospective review of all sonograms for acute appendicitis in children from May 2005 to May 2010 with attention to the rate of identification of the appendix, training of personnel involved and diagnostic accuracy.

RESULTS

The appendix was identified in 246/1,009 cases (24.4%), with identification increasing over time. The accuracy of US was 85-91% with 35 false-positives and 54 false-negatives. Pediatric sonographers were significantly better at identifying the appendix than non-pediatric sonographers (P < 0.0001). Increased weight was the only patient factor that influenced identification of the appendix (P = 0.006). CT use was stable over the 5 years but declined in cases where the appendix was identified by US.

CONCLUSION

In day-to-day use, US does not perform as purported in the literature. We do not visualize the appendix as often as we should and false-negative and false-positive exams are too common. To improve the diagnostic performance of this modality, involvement by experienced personnel and/or additional training is needed.

Reassessment of CT images to improve diagnostic accuracy in patients with suspected acute appendicitis and an equivocal preoperative CT interpretation

OBJECTIVES

To identify CT features that discriminate individuals with and without acute appendicitis in patients with equivocal CT findings, and to assess whether knowledge of these findings improves diagnostic accuracy.

METHODS

53 patients that underwent appendectomy with an indeterminate preoperative CT interpretation were selected and allocated to an acute appendicitis group or a non-appendicitis group. The 53 CT examinations were reviewed by two radiologists in consensus to identify CT findings that could aid in the discrimination of those with and without appendicitis. In addition, two additional radiologists were then requested to evaluate independently the 53 CT examinations using a 4-point scale, both before and after being informed of the potentially discriminating criteria.

RESULTS

CT findings found to be significantly different in the two groups were; the presence of appendiceal wall enhancement, intraluminal air in appendix, a coexistent inflammatory lesion, and appendiceal wall thickening (P < 0.05). Areas under the curves of reviewers 1 and 2 significantly increased from 0.516 and 0.706 to 0.677 and 0.841, respectively, when reviewers were told which CT variables were significant (P = 0.0193 and P = 0.0397, respectively).

CONCLUSIONS

Knowledge of the identified CT findings was found to improve diagnostic accuracy for acute appendicitis in patients with equivocal CT findings.

KEY POINTS

• Numerous patients with clinically equivocal appendicitis do not have acute appendicitis • Computed tomography (CT) helps to reduce the negative appendectomy rate • CT is not always infallible and may also demonstrate indeterminate findings • However knowledge of significant CT variables can further reduce negative appendectomy rate • An equivocal CT interpretation of appendicitis should be reassessed with this knowledge.

Amyand Hernia Diagnosed With Sonography

Individually, inguinal hernias and acute appendicitis are common, but the combination of the two, acute appendicitis within an inguinal hernia or Amyand hernia (AH), is rare. The overwhelming majority of AH cases are in males and discovered during surgery. To date, only three case reports in the literature of this pathology have been diagnosed with sonography. This is a report of an AH diagnosed in a woman with sonography.

Acute appendicitis: prospective evaluation of a diagnostic algorithm integrating ultrasound and low-dose CT to reduce the need of standard CT

OBJECTIVES

To evaluate an algorithm integrating ultrasound and low-dose unenhanced CT with oral contrast medium (LDCT) in the assessment of acute appendicitis, to reduce the need of conventional CT.

METHODS

Ultrasound was performed upon admission in 183 consecutive adult patients (111 women, 72 men, mean age 32) with suspicion of acute appendicitis and a BMI between 18.5 and 30 (step 1). No further examination was recommended when ultrasound was positive for appendicitis, negative with low clinical suspicion, or demonstrated an alternative diagnosis. All other patients underwent LDCT (30 mAs) (step 2). Standard intravenously enhanced CT (180 mAs) was performed after indeterminate LDCT (step 3).

RESULTS

No further imaging was recommended after ultrasound in 84 (46%) patients; LDCT was obtained in 99 (54%). LDCT was positive or negative for appendicitis in 81 (82%) of these 99 patients, indeterminate in 18 (18%) who underwent standard CT. Eighty-six (47%) of the 183 patients had a surgically proven appendicitis. The sensitivity and specificity of the algorithm were 98.8% and 96.9%.

CONCLUSIONS

The proposed algorithm achieved high sensitivity and specificity for detection of acute appendicitis, while reducing the need for standard CT and thus limiting exposition to radiation and to intravenous contrast media.

Negative appendectomy: a 10-year review of a nationally representative sample

BACKGROUND

Appendectomy remains one of the most common emergency surgical procedures encountered throughout the United States. With improvements in diagnostic techniques, the efficiency of diagnosis has increased over the years. However, the entity of negative appendectomies still poses a dilemma because these are associated with unnecessary risks and costs to both patients and institutions. This study was conducted to show current statistics and trends in negative appendectomy rates in the United States.

METHODS

A retrospective analysis was conducted using data from the National Inpatient Sample from 1998 to 2007. Adult patients (>18 y) having undergone appendectomies were identified by the appropriate International Classification of Diseases 9th revision codes. Patients with incidental appendectomy and those with appendiceal pathologies, also identified by relevant International Classification of Diseases 9th revision codes, were excluded. The remaining patients represent those who underwent an appendectomy without appendiceal disease. The patients then were stratified according to sex, women were classified further into younger (18-45 y) and older (>45 y) based on child-bearing age. The primary diagnoses subsequently were categorized by sex to identify the most common conditions mistaken for appendiceal disease in the 2 groups.

RESULTS

Between 1998 and 2007, there were 475,651 cases of appendectomy that were isolated. Of these, 56,252 were negative appendectomies (11.83%). There was a consistent decrease in the negative appendectomy rates from 14.7% in 1998 to 8.47% in 2007. Women accounted for 71.6% of cases of negative appendectomy, and men accounted for 28.4%. The mortality rate was 1.07%, men were associated with a higher rate of mortality (1.93% vs .74%; P < .001). Ovarian cyst was the most common diagnosis mistaken for appendicitis in younger women, whereas malignant disease of the ovary was the most common condition mistaken for appendiceal disease in women ages 45 and older. The most common misdiagnosis in men was diverticulitis of the colon.

CONCLUSIONS

There has been a consistent decline in the rates of negative appendectomy. This trend may be attributed to better diagnostics. Gynecologic conditions involving the ovary are the most common to be misdiagnosed as appendiceal disease in women.