Increased body mass index is associated with decreased imaging quality of point-of-care abdominal aortic ultrasonography.

BACKGROUND: Given that abdominal aorta is a retroperitoneal structure, increased body mass index (BMI) may have an adverse effect upon the quality of aortic ultrasonographic imaging. PURPOSE: To assess the hypothesis that increased BMI is associated with worsening point-of-care abdominal aortic ultrasonographic image quality. METHODS: This is a retrospective single-center study of point-of-care abdominal aortic ultrasound examinations performed in an academic emergency department (ED) with fellowship-trained emergency ultrasonography faculty performing quality assurance review. RESULTS: Mean ± SD BMI was 27.4 ± 6.2, among the 221 included records. The overall quality rating decreased as BMI increased (correlation coefficient - 0.24; P < .001) and this persisted after adjustment for age and sex (P < .001). Although BMI was higher on average in the records that were of insufficient quality for clinical decisions when compared with those of sufficient quality (mean BMI 28.7 vs 27.0), this did not reach statistical significance in a univariable setting (P = .11) or after adjusting for age and sex (P = .14). CONCLUSION: This study data shows a decrease in point-of-care abdominal aorta ultrasound imaging quality as BMI increases, though this difference did not result in a statistically significant impairment in achieving the minimum quality for clinical decisions. This finding may help ameliorate some clinician concerns about ultrasonography for patients with high BMI.

Increased body mass index does not impact the imaging quality of focused assessment with sonography in trauma.

BACKGROUND: Many clinicians believe that a patient's body mass index (BMI) affects the likelihood of obtaining high quality ultrasound images. OBJECTIVES: To assess the hypothesis that increased BMI is associated with worsening focused assessment with sonography in trauma (FAST) image quality. METHODS: We conducted a retrospective single-center study of FAST examinations performed in a large academic emergency department (ED) with fellowship-trained emergency ultrasonography faculty performing quality assurance review. RESULTS: Mean (SD) BMI was 28.0 (6.6) among the 302 included studies. The overall quality rating tended to decrease as BMI increased but did not achieve statistical significance in a univariable setting (P = .06) or after adjustment for age and sex (P = .06). Operators perception of image adequacy was largely unaffected by BMI, with the exception of the pericardial view. CONCLUSION: This study did not identify a statistically significant difference in FAST quality with increased BMI. This result may help assuage clinician concerns about ultrasonography for patients in the ED.

Ultrasound evaluation of appendicitis: importance of the 3 × 2 table for outcome reporting.

INTRODUCTION: Despite a relatively high frequency of appendix nonvisualization when using ultrasound to diagnose appendicitis, many studies either fail to report these results or inconsistently analyze outcomes. OBJECTIVES: The objective of this study is to determine the most transparent and accurate way of reporting and analyzing ultrasound results for the diagnosis of appendicitis. METHODS: This was an observational cohort study of emergency department patients age 18 years or older who underwent right lower quadrant ultrasonography from September 2010 to October 2011. Patient characteristics, imaging, pathology, and follow-up data were analyzed. Test characteristics were calculated using conventional 2 × 2 contingency table analysis excluding inconclusive ultrasound results and an intention-to-diagnose approach with a 3 × 2 table. RESULTS: Sixty-five patients were included. Forty-four (68%) patients had a nonvisualized appendix resulting in an overall diagnostic yield of 32%. Twenty-one patients had a visualized appendix (14 [22%] negative and 7 [11%] positive for appendicitis). Using 2 × 2 contingency table analysis, sensitivity and specificity were 100%. Using the 3 × 2 table with and the intention-to-diagnose principle, sensitivity was 70% and specificity was 25%. Three (7%) of 44 patients with a nonvisualized appendix had appendicitis (likelihood ratio = 0.40). DISCUSSION: We suggest reporting ultrasound results using a 3 × 2 table (including nonvisualized findings) but using the traditional 2 × 2 type of analysis for test characteristic calculations. This approach allows for the determination of diagnostic yield and calculation of likelihood ratios when the appendix is not visualized. This approach to reporting should be considered for all types of diagnostic ultrasound studies.