Accuracy of ultrasound for the diagnosis of acute appendicitis in the emergency department: A systematic review

BACKGROUND

Point-of-Care Ultrasound (POCUS) is a quick, useful, noninvasive, and inexpensive diagnostic tool used for the diagnosis of trauma, abdominal pain, dyspnea, and chest pain in the emergency department (ED). However, the diagnostic accuracy of ultrasound in the ED may be different from those reported in previous studies owing to the setting and time constraints in ED.

METHODS

We conducted our study in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines. A literature search was conducted using databases on US National Library of Medicine's database of biomedical literature, Ovid MEDLINE, online database of biomedical articles, and the collection of databases of systematic reviews and other evidence. The inclusion criteria were the use of bedside ultrasound as a diagnostic tool for acute appendicitis in the ED and the available data on diagnostic parameters such as sensitivity, specificity, and positive and negative predictive values (NPV). We constructed forest plots and summary receiver operating characteristic curves to evaluate the diagnostic accuracy of bedside ultrasound for acute appendicitis in the ED.

RESULTS

A total of 21 studies that met the inclusion criteria of this study were included for analysis. The overall pooled sensitivity was 0.81 (95% CI, 0.78-0.83), whereas the pooled specificity was 0.87 (95% CI, 0.85-0.88). However, the I2 test showed 91.7% and 90.9% heterogeneity in the sensitivity and specificity values, respectively. The summary receiver operating characteristic curves showed high levels of accuracy, as evidenced by an area under the curve of 0.9249 (standard error: 0.0180).

CONCLUSIONS

The use of ultrasound for the diagnosis of acute appendicitis in the ED showed that ultrasound has high overall sensitivity and specificity for the diagnosis of acute appendicitis. however, high heterogeneity among the included studies was observed.

Diagnostic performance of emergency physician-performed point-of-care ultrasonography for acute appendicitis: A meta-analysis

OBJECTIVE

To assess the sensitivity and specificity of emergency physician-performed point-of-care ultrasonography (EP-POCUS) for diagnosing acute appendicitis (AA).

MATERIAL AND METHODS

The PubMed and EMBASE databases were searched, and the diagnostic performance of EP-POCUS was evaluated using bivariate modeling and hierarchical summary receiver operating characteristic curves. Subgroup analysis was performed for pediatric patients to compare EP-POCUS and radiologist-performed ultrasonography (RADUS). Meta-regression analyses were performed according to patient and study characteristics.

RESULTS

In 17 studies (2385 patients), EP-POCUS for diagnosing AA exhibited a pooled sensitivity of 84% (95% confidence interval [CI]: 72%-92%) and a pooled specificity of 91% (95% CI: 85%-95%), with even better diagnostic performance for pediatric AA (sensitivity: 95%, 95% CI: 75%-99%; specificity: 95%, 95% CI: 85%-98%). A direct comparison revealed no significant differences (p = 0.18-0.85) between the diagnostic performances of EP-POCUS (sensitivity: 81%, 95% CI: 61%-90%; specificity: 89%, 95% CI: 77%-95%) and RADUS (sensitivity: 74%, 95% CI: 65%-81%; specificity: 97%, 95% CI: 93%-98%). The meta-regression analyses revealed that study location, AA proportion, and mean age were sources of heterogeneity. Higher sensitivity and specificity tended to be associated with an appendix diameter cut-off value of 7 mm and the EP as the initial operator.

CONCLUSION

The diagnostic performances of EP-POCUS and RADUS were excellent for AA, with EP-POCUS having even better performance for pediatric AA. Accurate diagnoses may be achieved when the attending EP is the initial POCUS operator and uses a 7-mm cut-off value.

Accuracy of Point-of-care Ultrasonography for Diagnosing Acute Appendicitis: A Systematic Review and Meta-analysis

BACKGROUND

The use of ultrasonography (US) to diagnose appendicitis is well established. More recently, point-of-care ultrasonography (POCUS) has also been studied for the diagnosis of appendicitis, which may also prove a valuable diagnostic tool. The purpose of this study was through systematic review and meta-analysis to identify the test characteristics of POCUS, specifically US performed by a nonradiologist physician, in accurately diagnosing acute appendicitis in patients of any age.

METHODS

We conducted a thorough and systematic literature search of English language articles published on point-of-care, physician-performed transabdominal US used for the diagnosis of acute appendicitis from 1980 to May, 2015 using OVID MEDLINE In-Process & Other Non-indexed Citations and Scopus. Studies were selected and subsequently independently abstracted by two trained reviewers. A random-effects pooled analysis was used to construct a hierarchical summary receiver operator characteristic curve, and a meta-regression was performed. Quality of studies was assessed using the QUADAS-2 tool.

RESULTS

Our search yielded 5,792 unique studies and we included 21 of these in our final review. Prevalence of disease in this study was 29.8%, (range = 6.4%-75.4%). The sensitivity and specificity for POCUS in diagnosing appendicitis were 91% (95% confidence interval [CI] = 83%-96%) and 97% (95% CI = 91%-99%), respectively. The positive and negative predictive values were 91 and 94%, respectively. Studies performed by emergency physicians had slightly lower test characteristics (sensitivity = 80%, specificity = 92%). There was significant heterogeneity between studies (I² = 99%, 95% CI = 99%-100%) and the quality of the reported studies was moderate, mostly due to unclear reporting of blinding of physicians and timing of scanning and patient enrollment. Several of the studies were performed by a single operator, and the education and training of the operators were variably reported.

CONCLUSION

Point-of-care US has relatively high sensitivity and specificity for diagnosing acute appendicitis, although the data presented are limited by the quality of the original studies and large CIs. In the hands of an experienced operator, POCUS is an appropriate initial imaging modality for diagnosing appendicitis. Based on our results, it is premature to utilize POCUS as a stand-alone test or to rule out appendicitis.