Imaging trends in suspected appendicitis-a Canadian perspective

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

OBJECTIVES

To perform a systematic review on the use of magnetic resonance imaging (MRI) of the abdomen to evaluate clinically suspected appendicitis in the general adult population. We examined the diagnostic accuracy, the reported trends of MRI use, and the factors that affect the utility of MRI abdomen, including study duration and cost-benefits.

METHODS

We conducted a systematic literature search on PubMed, MEDLINE, Embase, Web of Science, and Cochrane Library databases. We enrolled primary studies investigating the use of MRI in diagnosing appendicitis in the general adult population, excluding studies that predominantly reported on populations not representative of typical adult appendicitis presentations, such as those focusing on paediatric or pregnant populations.

RESULTS

Twenty-seven eligible primary studies and 6 secondary studies were included, totaling 2,044 patients from eight countries. The sensitivity and specificity of MRI for diagnosing appendicitis were 96% (95% CI: 93-97%) and 93% (95% CI: 80-98%), respectively. MRI can identify complicated appendicitis and accurately propose alternative diagnoses. The duration of MRI protocols in each primary study ranged between 2.26 and 30 minutes, and only one study used intravenous contrast agents in addition to the non-contrast sequences. Decision analysis suggests significant benefits for replacing computed tomography (CT) with MRI and a potential for cost reduction. Reported trends in MRI usage showed minimal utilisation in diagnostic settings even when MRI was available.

CONCLUSIONS

MRI accurately diagnoses appendicitis in the general adult population and improves the identification of complicated appendicitis or alternative diagnoses compared to other modalities using a single, rapid investigation.

Ultrasound for Suspected Acute Appendicitis in Adult Women Under Age 40: An Evaluation of On-Call Radiology Resident Scanning

RATIONALE AND OBJECTIVES

At our institution, on-call radiology residents perform emergent ultrasounds (US) outside of departmental working hours. The aim of the study was to evaluate radiology resident-performed US for clinically suspected acute appendicitis in women under the age of 40.

MATERIALS AND METHODS

Retrospective review of 104 consecutive US scans outside of departmental working hours by radiology residents, and 104 consecutive US studies scanned during departmental working hours by sonographers, in women under the age of 40 for clinically suspected appendicitis .

RESULTS

Appendix visualization rate was 27% for the resident group (sonographer group: 30%, p = 0.759). The sensitivity and specificity of US for appendicitis were 63% (95% confidence interval: 41%-81%) and 98% (95% CI: 91%-100%), respectively for the resident group (sonographer group: 69% [95% CI: 41%-89 %] and 98% [95% CI: 92%-100%], respectively). An alternative cause for right lower quadrant pain was offered in 17% of resident group cases (sonographer group: 21%, p = 0.598). Follow-up CT or MRI was performed in 47% of resident cases (sonographer group: 44%, p = 0.781). Residents performed more focused US (i.e. not imaging the pelvic organs), at 34% (sonographer group: 1%, p < 0.001). When only focused scanning was performed by residents, there was a trend toward increased downstream imaging (CT or MRI), odds ratio = 2.76 (95% CI: 0.99-7.70).

CONCLUSIONS

Out-of-hours US scans performed by radiology residents had similar performance characteristics compared to departmental sonographers. We discovered an increased rate of downstream imaging in cases in which residents performed limited scans and did not document visualization of the pelvic organs.

Accuracy of ultrasound exam performed by emergency medicine versus radiology residents in the diagnosis of acute appendicitis

BACKGROUND

Although the traditional approach to the diagnosis of acute appendicitis (AA) is using clinical methods, experience has shown that strict reliance on clinical data can lead to mismanagement or unnecessary surgery.

OBJECTIVE

The objective of this study was to determine the total agreement of ultrasound (US) results in AA performed by emergency medicine (EM) versus radiology residents in emergency department.

PATIENTS AND METHODS

In this cross-sectional study, 121 patients with AA suspicion underwent an US exam by both trained EM and radiology residents in emergency department. The training course for EM residents consisted of attending an 8-h-workshop and then practicing an US exam on real patients within a 2-month period. The gold standards were either histopathologic or follow-up results. Total agreement of the results in both specialties was compared.

RESULTS

There were 67 men and 54 women, with a mean age of 33.6 ± 16.1 years (18.2-88.7 years). Fifty-four (44.6%) patients underwent surgery with the initial diagnosis of AA and the rest were evaluated by follow-ups. On the basis of our gold standards, the diagnosis was finally confirmed in 46 (38%) cases. There was a high total agreement in AA diagnosis [96% agreement, κ = 0.90; 95% confidence interval (CI) = 0.81-0.99] between the two groups. The specificity and sensitivity of EM and radiology groups were 99% (95% CI = 93-100), 63% (95% CI = 48-77), 97% (95% CI = 91-100), and 72% (95% CI = 57-84), respectively.

CONCLUSION

US has a high diagnostic specificity in patients suspected of having AA and EM residents can perform this modality as accurately as radiologists after training in the emergency setting.

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.

Clinical Ultrasound Is Safe and Highly Specific for Acute Appendicitis in Moderate to High Pre-test Probability Patients

Introduction

Clinical ultrasound (CUS) is highly specific for the diagnosis of acute appendicitis but is operator-dependent. The goal of this study was to determine if a heterogeneous group of emergency physicians (EP) could diagnose acute appendicitis on CUS in patients with a moderate to high pre-test probability.

Methods

This was a prospective, observational study of a convenience sample of adult and pediatric patients with suspected appendicitis. Sonographers received a structured, 20-minute CUS training on appendicitis prior to patient enrollment. The presence of a dilated (>6 mm diameter), non-compressible, blind-ending tubular structure was considered a positive study. Non-visualization or indeterminate studies were considered negative. We collected pre-test probability of acute appendicitis based on a 10-point visual analog scale (moderate to high was defined as >3), and confidence in CUS interpretation. The primary objective was measured by comparing CUS findings to surgical pathology and one week follow-up.

Results

We enrolled 105 patients; 76 had moderate to high pre-test probability. Of these, 24 were children. The rate of appendicitis was 36.8% in those with moderate to high pre-test probability. CUS were recorded by 33 different EPs. The sensitivity, specificity, and positive and negative likelihood ratios of EP-performed CUS in patients with moderate to high pre-test probability were 42.8% (95% confidence interval [CI] [25–62.5%]), 97.9% (95% CI [87.5–99.8%]), 20.7 (95% CI [2.8–149.9]) and 0.58 (95% CI [0.42–0.8]), respectively. The 16 false negative scans were all interpreted as indeterminate. There was one false positive CUS diagnosis; however, the sonographer reported low confidence of 2/10.

Conclusion

A heterogeneous group of EP sonographers can safely identify acute appendicitis with high specificity in patients with moderate to high pre-test probability. This data adds support for surgical consultation without further imaging beyond CUS in the appropriate clinical setting.