Comparison of Imaging Strategies with Conditional versus Immediate Contrast-Enhanced Computed Tomography in Patients with Clinical Suspicion of Acute Appendicitis

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

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

The uncommon preoperative diagnosis of a De Garengeot hernia and its more novel laparoscopic treatment

This case report involves an elderly woman who presented with a 3-day history of a tender groin swelling on her right side. Her admission bloods were fairly unremarkable, but a preoperative ultrasound impressively confirmed a femoral hernia containing the appendix (De Garengeot hernia) and she underwent emergency laparoscopic hernioplasty with a prosthetic mesh and appendicectomy. The procedure found an incarcerated hernia with a strangulated tip of the appendix that unexpectedly separated upon gentle manipulation and histopathology revealed appendiceal inflammation. There were no complications with the patient's recovery and she was discharged 2 days after surgery.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Diagnostic accuracy of computed tomography and ultrasound for the diagnosis of acute appendicitis: A systematic review and meta-analysis

INTRODUCTION

The diagnosis of acute appendicitis remains challenging. This review determined the current diagnostic accuracy of CT and ultrasound for suspected acute appendicitis in adults.

METHODS

This systematic review adhered to the PRISMA for diagnostic test accuracy guidelines. A systematic search was undertaken in appropriate databases. Screening of potential titles and abstracts, full-text retrieval, methodological quality assessment using QUADAS, and data extraction was performed. Meta-analyses were performed for relevant subgroups, and sensitivity analysis was completed to account for outliers. GRADE was utilized to assess the certainty of findings.

RESULTS

31 studies evaluating CT, 10 evaluating US, and six evaluating both were included. Pooled sensitivity and specificity for CT was 0.972 [0.958, 0.981] and 0.956 [0.941, 0.967] respectively, and 0.821 [0.738, 0.882] and 0.859 [0.727, 0.933] for US, respectively. When analyzing subgroups based on the use of contrast enhancement, sensitivity and specificity was highest for CT with intravenous and oral contrast (0.992 [0.965, 0.998], 0.974 [0.936, 0.99]), compared to CT with intravenous contrast (0.955 [0.922, 0.974], 0.942 [0.916, 0.960]). Low-Dose CT produced comparable values (0.934 [0.885,0.963], 0.937 [0.911, 0.955]) relative to these subgroups and standard dose non-contrast CT (0.877 [0.774,0.937], 0.914 [0.827, 0.959]). US studies which excluded equivocal findings demonstrated significantly greater values than the remainder of US studies (p < 0.0001).

CONCLUSION

The updated diagnostic test accuracies of CT, US and relevant subgroups should be implemented in light of factors such as dose, cost, and timing.

IMPLICATIONS FOR PRACTICE

For diagnosis of adult acute appendicitis: • CT with intravenous plus oral contrast enhancement yields statistically significantly greater diagnostic accuracy than CT with intravenous contrast alone. • Low-dose CT yields comparable sensitivity and specificity to standard-dose CT. • Ultrasound studies which exclude equivocal results may overinflate sensitivity and specificity.

Diagnostic accuracy of a pragmatic, ultrasound-based approach to adult patients with suspected acute appendicitis in the ED

BACKGROUND

Systematic imaging reduces the rate of missed appendicitis and negative appendectomies in patients with suspected acute appendicitis (AA). Little is known about the utility of ultrasound as a first diagnostic measure in patients with suspected AA. The aim of this retrospective study is to determine whether ultrasound, performed by emergency physicians or radiologists, can be used as first diagnostic measure in suspected cases to rule out AA and to avoid unnecessary CT.

METHODS

We performed a retrospective analysis at the ED of the University Hospital Bern, Switzerland, from 2012 to 2014. Our standard protocol is that all adult patients suspected of appendicitis receive an ultrasound as their first imaging test, either by an emergency physician or a radiologist. The test characteristics of conclusive and inconclusive ultrasound exams were compared with a pragmatic gold standard.

RESULTS

The study included 508 patients with suspected AA. 308 patients (60.4%) had a conclusive ultrasound. Among these, sensitivity for appendicitis was 89.6% (95% CI 82.1% to 94.3%), specificity 93.8% (89.1% to 96.6%), the positive predictive value was 87.98 (80.84 to 92.71) and the negative predictive value was 94.65 (91.18 to 96.80). The remaining 200 (39.4%) patients had an inconclusive ultrasound exam. 29% (59/200) of these patients ultimately had appendicitis. Less experienced emergency physician sonographers came to a definitive conclusion in 48.1% (95% CI 36.9% to 59.5%), experienced emergency physician sonographers in 76.0% (68.4% to 82.5%) and radiologists in 52.4% (44.5% to 60.2%).

CONCLUSION

A conclusive ultrasound of the appendix performed by either emergency physicians or radiologists is a sensitive and specific exam to diagnose or exclude AA in patients with suspected AA. Because of 6% false negative exams, clinical follow-up is mandatory for patients with negative ultrasound. An inconclusive ultrasound warrants further imaging or a follow-up visit, since 29% of patients with inconclusive ultrasound had an AA.

The Dynamics of Inflammatory Markers in Patients with Suspected Acute Appendicitis

Background: Laboratory tests of inflammatory mediators are routinely used in the diagnosis of acute appendicitis (AA). The aim of this study was to evaluate the differences of dynamics of inflammatory markers of the blood in patients with suspected acute appendicitis between complicated AA (CAA), non-complicated AA (NAA), and when AA was excluded (No-AA). Methods: This was a retrospective analysis of prospectively collected data of patients presented to the Emergency Department (ER) of a tertiary hospital center during a three-year period. All patients suspected of acute appendicitis were prospectively registered from 1 January 2016 to 31 December 2018. The dynamics of inflammatory markers of the blood between different types of AA (No-AA, NAA or CAA) during different periods of time are presented. Results: A total of 453 patients were included in the study, with 297 patients in the No-AA group, 99 in the NAA group, and 57 in the CAA group. White blood cell (WBC) count in the No-AA decreased with time, with a statistically significant difference between the <8 h and 25–72 h group. The neutrophils (NEU) percentage decreased in the No-AA group and was statistically significantly different between the <8 h and 25–72 h and <8 h and >72 h groups. C-reactive protein (CRP) increased significantly in the No-AA group throughout all time intervals, and from the first 24 h to the 25–72 h in the NAA and CAA groups. There was a statistically significant difference between the WBC count between No-AA, NAA, and No-AA and CAA groups during the first 24 and 24–48 h. There was a statistically significant difference between NEU percentage and LYMP percentage and in the NEU/LYMP ratio between No-AA and CAA groups through all time periods. CRP was significantly higher in the first 24 h in the CAA than in the No-AA group, and in the 24–48 h in the CAA group than in the No-AA and NAA groups. The linear logistic regression model, involving inflammatory mediators and clinical characteristics, showed mediocre diagnostic accuracy for diagnosing AA with an AUC of 0.737 (0.671–0.802). Conclusions: Increasing concentrations of inflammatory markers are more characteristic in CAA patients than in No-AA during the first 48 h after onset of the disease. A combination of laboratory tests with clinical signs and symptoms has a mediocre diagnostic accuracy in suspecting AA.

Conditional CT Strategy-An Effective Tool to Reduce Negative Appendectomy Rate and the Overuse of the CT

(1) Background: Diagnosis of acute appendicitis (AA) remains challenging; either computed tomography (CT) is universally used or negative appendectomy rates of up to 30% are reported. Transabdominal ultrasound (TUS) as the first-choice imaging modality might be useful in adult patients to reduce the need for CT scans while maintaining low negative appendectomy (NA) rates. The aim of this study was to report the results of the conditional CT strategy for the diagnosis of acute appendicitis. (2) Methods: All patients suspected of acute appendicitis were prospectively registered from 1 January 2016 to 31 December 2018. Data on their clinical, radiological and surgical outcomes are presented. (3) Results: A total of 1855 patients were enrolled in our study: 1206 (65.0%) were women, 649 (35.0%) were men, and the median age was 34 years (IQR, 24.5–51). TUS was performed in 1851 (99.8%) patients, and CT in 463 (25.0%) patients. Appendices were not visualized on TUS in 1320 patients (71.3%). Furthermore, 172 (37.1%) of 463 CTs were diagnosed with AA, 42 (9.1%) CTs revealed alternative emergency diagnosis and 249 (53.8%) CTs were normal. Overall, 519 (28.0%) patients were diagnosed with AA: 464 appendectomies and 27 diagnostic laparoscopies were performed. The NA rate was 4.2%. The sensitivity and specificity for TUS and CT are as follows: 71.4% and 96.2%; 93.8% and 93.6%. (4) Conclusion: A conditional CT strategy is effective in reducing NA rates and avoids unnecessary CT in a large proportion of patients. Observation and repeated TUS might be useful in unclear cases.

Validation of a Scoring System to Distinguish Uncomplicated From Complicated Appendicitis

BACKGROUND

Studies have shown that uncomplicated appendicitis can be treated conservatively with antibiotics. It is important to select only those patients with uncomplicated appendicitis when considering conservative management. Recently, a scoring system based on clinical evaluation and ultrasound was developed to improve this selection and aid in shared decision making when considering an antibiotics-first strategy. The aim of this study was to externally validate the scoring system.

MATERIALS AND METHODS

A retrospective cohort study of all adult patients presenting to the emergency department between January 2014 and January 2017 with suspected acute appendicitis based on clinical evaluation and ultrasound was performed. For every patient, a score was calculated using the previously described scoring system. A final diagnosis, subdivided into complicated appendicitis, uncomplicated appendicitis, complicated alternative disease, and uncomplicated alternative disease, was assigned to every patient based on operative findings.

RESULTS

A total of 678 patients with suspected acute appendicitis based on clinical and ultrasonography findings were identified, of whom 175 (25.8%) had complicated appendicitis, 491 (72.4%) had uncomplicated appendicitis, and 12 (1.8%) had an alternative disease. Of the 678 patients, 272 had a score of five points or less, of whom 17 (6.2%) had complicated appendicitis, giving a negative predictive value of 93.8%.

CONCLUSIONS

With the scoring system based on clinical and ultrasonography features, 93.8% of patients predicted to have uncomplicated appendicitis were correctly identified. The scoring system could help identify patients suitable for conservative management in future studies.

ACR Appropriateness Criteria® Suspected Appendicitis-Child

Acute appendicitis represents the most common abdominal surgical urgency/emergency in children. Imaging remains a central tool in the diagnosis of acute appendicitis and has been shown to facilitate management and decrease the rate of negative appendectomies. The initial consideration for imaging in a child with suspected acute appendicitis is based on clinical assessment, which can be facilitated with published scoring systems. The level of clinical risk (low, intermediate, high) and the clinical scenario (suspicion for complication) define the need for imaging and the optimal imaging modality. In some situations, no imaging is required, while in others ultrasound, CT, or MRI may be appropriate. This review frames the presentation of suspected acute appendicitis in terms of the clinical risk and also discusses the unique situations of the equivocal or nondiagnostic initial ultrasound examination and suspected appendicitis with suspicion for complication (eg, bowel obstruction). The American College of Radiology Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed annually by a multidisciplinary expert panel. The guideline development and revision include an extensive analysis of current medical literature from peer reviewed journals and the application of well-established methodologies (RAND/UCLA Appropriateness Method and Grading of Recommendations Assessment, Development, and Evaluation or GRADE) to rate the appropriateness of imaging and treatment procedures for specific clinical scenarios. In those instances where evidence is lacking or equivocal, expert opinion may supplement the available evidence to recommend imaging or treatment.

The Results of Abdominopelvic Computed Tomography Interpreted via Remote Access for the Diagnosis of Acute Appendicitis

INTRODUCTION

Abdominal computed tomography (CT) is one of the imaging modalities for the diagnosis of acute appendicitis (AA). Today, CT scans can be interpreted via remote access called tele-radiology, besides conventional methods. The objective of this study was to evaluate the CT interpreted via tele-radiology for diagnosing AA.

METHODS

In this retrospective study, a total of 679 patients, who were interpreted via tele-radiology of CT due to suspicion of AA, were evaluated. Age, gender, CT findings, pathology results and intra-operative diagnosis of those with normal CT results were analysed. A sensitivity, specificity, accuracy, positive predictive values (PPV) and negative predictive values (NPV) of CT in the diagnosis of AA were calculated.

RESULTS

520 patients who were operated with pre-diagnosed AA were found. Of those, 441 patients (84.8%) were diagnosed with AA according to CT reports, out of which 368 (83.4%) were positive (true-positive) and 73 (16.6%) were negative (false-positive) in terms of pathology results. In the remaining operated 79 patients with normal CT results, 58 (73.4%) were positive for AA and 21 (26.6%) (negative laparotomy) were negative for AA in terms of pathological examination. The sensitivity, specificity, accuracy, PPV and NPV of CT in the diagnosis of AA were determined as 81.2%, 67.7%, 76.7%, 83.4% and 64.2%, respectively.

CONCLUSION

The sensitivity and PPV rates were found similar in both conventional and tele-radiological methods. However, specificity, accuracy and NPV rates were determined lower than in literature. Additionally, the negative laparotomy rate was higher than the conventional method.

Ultrasound diagnosis of acute appendicitis complicating De Garengeot's hernia

De Garengeot's hernia is a rare condition defined by the herniation of the vermiform appendix within a femoral hernia sac. We report a case of an 80-year-old woman admitted to our emergency department complaining of pain in the right groin. This symptomatology, present for 2 days, increased in the following 12 h. Ultrasonography (US) and contrast-enhanced computed tomography (CECT) were performed, which showed the herniation of the vermiform appendix in the femoral hernia sac. Doppler ultrasonography (DUS) and CECT were the fundamental imaging investigations for this diagnosis. The management of De Garengeot's hernia is surgical through herniorrhaphy, which makes it possible to repair the femoral hernia and perform an appendicectomy in case of appendicitis.

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.

Emphysematous pancreatitis associated with penetrating duodenal ulcer

In the “proton pump inhibitors era”, a penetrating peptic ulcer (PPU) represents an exceptional cause of abdominal pain, and was more frequently observed in the past where there was not an effective antacid treatment. Ulcer-induced pancreatitis is very rare, too, and manifests with persistent, intense pain radiating to the back. A mild to severe pancreatitis with peripancreatic fluid collection can be observed at imaging. However, only a few cases of association between PPU and emphysematous pancreatitis (EP) have been published in the literature. EP is a rare but potentially fatal form of acute necrotizing pancreatitis in which gas grows in and outside the pancreas, and typically involves the whole parenchyma in diabetic individuals.

Here we report an extremely rare case of a duodenal ulcer penetrating the pancreas and complicated with EP. Unlike the classic form of EP, which involves the whole parenchyma and has a poor prognosis, we found that the emphysematous involvement of the pancreas by PPU has a benign course if a conservative therapy is promptly established. Gas is confined to the site of penetration, usually the pancreatic head, and ulcers most often involve the duodenum.

The immune impact of mimic endoscopic retrograde appendicitis therapy and appendectomy on rabbits of acute appendicitis

This study was conducted to evaluate the immune impact of mimic endoscopic retrograde appendicitis therapy and appendectomy on rabbits of acute suppurative appendicitis and to determine whether TLR4/MYD88/NF-κB signaling pathway was activated in this process. 48 rabbits were assigned into 4 groups: group I, the mimic endoscopic retrograde appendicitis therapy group; group II, the appendectomy group; group III, the model group; and group IV, the blank group. White blood cells decreased, while levels of C-reactive protein, tumor necrosis factor-α, interleukin-6, interleukin-4, and interleukin-10 increased on the 2^nd day in group I and II. IgA in feces decreased at 2 weeks, while fecal microbiota changed at 2 and 4 weeks after appendectomy. CD8⁺ cells in appendix of group I increased within 8 weeks. Upregulated expression of TLR4, MYD88, and nuclear NF-κB were detected on the 2^nd day in group I and II. Mimic endoscopic retrograde appendicitis therapy and appendectomy are effective ways for acute suppurative appendicitis. Mimic endoscopic retrograde appendicitis therapy was more preferable due to its advantage in maintaining intestinal immune function. TLR4/MYD88/NF-κB signaling pathway was activated in acute phase of appendicitis.

The Introduction of Adult Appendicitis Score Reduced Negative Appendectomy Rate

BACKGROUND AND AIMS

Implementation of a clinical risk score into diagnostics of acute appendicitis may provide accurate diagnosis with selective use of imaging studies. The aim of this study was to prospectively validate recently described diagnostic scoring system, Adult Appendicitis Score, and evaluate its effects on negative appendectomy rate.

MATERIAL AND METHODS

Adult Appendicitis Score stratifies patients into three groups: high, intermediate, and low risk of appendicitis. The score was implemented in diagnostics of adult patients suspected of acute appendicitis in two university hospitals. We analyzed the effects of Adult Appendicitis Score on diagnostic accuracy, imaging studies, and treatment. The study population was compared with a reference population of 829 patients suspected of acute appendicitis originally enrolled for the study of construction of the Adult Appendicitis Score.

RESULTS

This study enrolled 908 patients of whom 432 (48%) had appendicitis. The score stratified 49% of all appendicitis patients into high-risk group with specificity of 93.3%. In the low-risk group, prevalence of appendicitis was 7%. The histologically confirmed negative appendectomy rate decreased from 18.2% to 8.7%, p<0.001, compared to the original dataset.

CONCLUSION

Adult Appendicitis Score is a reliable tool for stratification of patients into selective imaging, which results in low negative appendectomy rate.

Performance of imaging studies in patients with suspected appendicitis after stratification with adult appendicitis score

Background

Diagnostic scoring is used to stratify patients with suspected appendicitis into three groups: high, intermediate, and low probability of appendicitis. The stratification can be used for selective imaging to avoid the harms of radiation without compromising diagnostic accuracy.

The aim was to study how stratification by Adult Appendicitis Score affects diagnostic performance of imaging studies.

Methods

Analysis of 822 patients who underwent diagnostic imaging for suspected appendicitis was made. Adult Appendicitis Score was used to stratify patients into groups of high, intermediate, and low probability of appendicitis. Diagnostic performance of computed tomography (CT) and ultrasound (US) was compared between these patient groups.

Results

After scoring, pre-test probability of appendicitis ranged from 9-16% in low probability group to 75-79% in high probability group in patients who underwent US or CT. Post-test probability of appendicitis after positive CT was 99, 91, and 75% in high probability, intermediate probability and low probability groups, respectively, p < 0.001. After positive US the respective probabilities were 95, 91 and 42%, p < 0.001.

Conclusion

Diagnostic imaging has limited value in patients with low probability of appendicitis according to Adult Appendicitis Score.

A new technique for the diagnosis of acute appendicitis: abdominal CT with compression to the right lower quadrant

OBJECTIVE

To determine the diagnostic accuracy of abdominal CT with compression to the right lower quadrant (RLQ) in adults with acute appendicitis.

METHODS

168 patients (age range, 18-78 years) were included who underwent contrast-enhanced CT for suspected appendicitis performed either using compression to the RLQ (n = 71) or a standard protocol (n = 97). Outer diameter of the appendix, appendiceal wall thickening, luminal content and associated findings were evaluated in each patient. Kruskal-Wallis, Fisher's and Pearson's chi-squared tests were used for statistical analysis.

RESULTS

There was no significant difference in the mean outer diameter (MOD) between compression CT scans (10.6 ± 1.9 mm) and standard protocol (11.2 ± 2.3 mm) in patients with acute appendicitis (P = 1). MOD was significantly lower in the compression group (5.2 ± 0.8 mm) compared to the standard protocol (6.5 ± 1.1 mm) (P < 0.01) in patients without appendicitis. A cut-off value of 6.75 mm for the outer diameter of the appendix was found to be 100% sensitive in the diagnosis of acute appendicitis for both groups. The specificity was higher for compression CT technique (67.7 vs. 94.9%).

CONCLUSION

Normal appendix diameter was significantly smaller in the compression-CT group compared to standard-CT group, increasing diagnostic accuracy of abdominal compression CT.

KEY POINTS

• Normal appendix diameter is significantly smaller in compression CT. • Compression could force contrast material to flow through the appendiceal lumen. • Compression CT may be a CT counterpart of graded compression US.

Diagnosing acute appendicitis: surgery or imaging?

AIM

Investigation of suspected appendicitis varies widely across different countries, which creates variation in outcome for patients. Use of imaging drives much of this variation, with concerns over delay of imaging and radiation exposure of computed tomography being balanced against the risks of unnecessary surgery.

METHOD

Two national, prospective snapshot audits (UK n = 3326 and Netherlands n = 1934) reported investigation, management and outcome of appendicectomy and can be compared to generate treatment recommendations.

RESULTS

Preoperative imaging was conducted in 32.8% of UK patients in contrast to 99.5% of patients in the Netherlands. A large difference in the normal appendicectomy rate was observed (20.6% in the UK vs 3.2% in the Netherlands) and the connection between these two outcome differences cannot be neglected.

CONCLUSION

This article discusses the role of imaging in the diagnostic work-up of patients who are suspected of acute appendicitis, comparing national snapshot studies as a model to do so.

Lower Abdominal Pain

Although most frequently presenting with lower abdominal pain, appendicitis, colitis, and diverticulitis can cause pain throughout the abdomen and can cause peritoneal and retroperitoneal symptoms. Evaluation and management of lower intestinal disease requires a nuanced approach by the emergency physician, sometimes requiring computed tomography, ultrasonography, MRI, layered imaging, shared decision making, serial examination, and/or close follow-up. Once a presumed or confirmed diagnosis is made, appropriate treatment is initiated, and may include surgery, antibiotics, and/or steroids. Appendicitis patients should be admitted. Diverticulitis and inflammatory bowel disease can frequently be managed on an outpatient basis, but may require admission and surgical consultation.

How to diagnose acute appendicitis: ultrasound first

Acute appendicitis (AA) is a common abdominal emergency with a lifetime prevalence of about 7 %. As the clinical diagnosis of AA remains a challenge to emergency physicians and surgeons, imaging modalities have gained major importance in the diagnostic work-up of patients with suspected AA in order to keep both the negative appendectomy rate and the perforation rate low. Introduced in 1986, graded-compression ultrasound (US) has well-established direct and indirect signs for diagnosing AA. In our opinion, US should be the first-line imaging modality, as graded-compression US has excellent specificity both in the paediatric and adult patient populations. As US sensitivity is limited, and non-diagnostic US examinations with non-visualization of the appendix are more a rule than an exception, diagnostic strategies and algorithms after non-diagnostic US should focus on clinical reassessment and complementary imaging with MRI/CT if indicated. Accordingly, both ionizing radiation to our patients and cost of pre-therapeutic diagnosis of AA will be low, with low negative appendectomy and perforation rates.

Main Messages

• Ultrasound (US) should be the first imaging modality for diagnosing acute appendicitis (AA).

• Primary US for AA diagnosis will decrease ionizing radiation and cost.

• Sensitivity of US to diagnose AA is lower than of CT/MRI.

• Non-visualization of the appendix should lead to clinical reassessment.

• Complementary MRI or CT may be performed if diagnosis remains unclear.

Systematic review and meta-analysis of the accuracy of MRI to diagnose appendicitis in the general population

PURPOSE

To perform a systematic review and meta-analysis of all published studies since 2005 that evaluate the accuracy of magnetic resonance imaging (MRI) for the diagnosis of acute appendicitis in the general population presenting to emergency departments.

MATERIALS AND METHODS

All retrospective and prospective studies evaluating the accuracy of MRI to diagnose appendicitis published in English and listed in PubMed, Web of Science, Cinahl Plus, and the Cochrane Library since 2005 were included. Excluded studies were those without an explicitly stated reference standard, with insufficient data to calculate the study outcomes, or if the population enrolled was limited to pregnant women or children. Data were abstracted by one investigator and confirmed by another. Data included the number of true positives, true negatives, false positives, false negatives, number of equivocal cases, type of MRI scanner, type of MRI sequence, and demographic data including study setting and gender distribution. Summary test characteristics were calculated. Forest plots and a summary receiver operator characteristic plot were generated.

RESULTS

Ten studies met eligibility criteria, representing patients from seven countries. Nine were prospective and two were multicenter studies. A total of 838 subjects were enrolled; 406 (48%) were women. All studies routinely used unenhanced MR images, although two used intravenous contrast-enhancement and three used diffusion-weighted imaging. Using a bivariate random-effects model the summary sensitivity was 96.6% (95% confidence interval [CI]: 92.3%-98.5%) and summary specificity was 95.9% (95% CI: 89.4%-98.4%).

CONCLUSION

MRI has a high sensitivity and specificity for the diagnosis of appendicitis, similar to that reported previously for computed tomography. J. Magn. Reson. Imaging 2016;43:1346-1354.