Defining Laterality of the Descending Thoracic Aorta in a 4‐Chamber View of the Heart

Objective. Right descending aortas have been correlated with an increased risk of congenital heart disease. Nevertheless, the aortic position remains a largely overlooked diagnostic tool in second‐trimester sonography because no formal system for assessing the position exists. By developing a method of assigning the position of the aorta relative to the thoracic midline, diagnostic use of the descending aorta's position might be implemented more easily. Methods. The method of assessing the position relative to the midline was tested by comparing the analysis of 2 independent observers, who showed a 94.4% concordance rate. Results. Comparison of the percentages of aortic positions between the gestational ages (GAs) of 18 and 21 weeks showed no significant correlation between the aortic position and GA. Conclusions. We suggest simply paying attention to the aortic position in an already standard view. The extra effort is minimal, and it has the potential to improve the diagnostic accuracy of the 4‐chamber view.     

Prenatal 3‐Dimensional Imaging Techniques in the Sonographic Evaluation of an Oral Mass

Historically, published reports of 3‐dimensional (3D) sonographic evaluation of fetal oral masses have been limited to the surface‐rendering mode. This report demonstrates the clinical potential of various 3D imaging techniques in the evaluation of fetal epignathus. A comparison is made among the images generated from 3D data sets, postnatal magnetic resonance imaging and computed tomographic scans, and the excised surgical specimen. The diagnostic value and limitations of several 3D imaging techniques in the evaluation of an oral mass are explored.     

The Double-Line Sign: A False Positive Finding on the Focused Assessment with Sonography for Trauma (FAST) Examination

Background: Emergency physicians commonly perform Focused Assessment with Sonography for Trauma (FAST) examinations to evaluate for free intraperitoneal fluid. Many ultrasound findings can be misinterpreted as free fluid, resulting in false-positive FAST examinations. Objectives: To describe a previously unreported ultrasound finding that can be misinterpreted as free intraperitoneal fluid. Case Report: A 32-year-old man was stabbed in the left upper abdomen. A FAST examination was performed and a right perinephric fat pad was interpreted as showing free fluid in Morison's pouch. After transfer to a trauma center, a repeat FAST examination revealed no signs of intraperitoneal free fluid. Wound exploration showed no signs of penetration into the peritoneal cavity. Conclusions: When performing a FAST examination, a wedge-shaped hypoechoic area in Morison's pouch that is bounded on both sides by echogenic lines (the “FAST Double-Line Sign”) is likely to represent perinephric fat and may result in a false-positive FAST examination.     

Language of Transducer Manipulation

There is a need for consistent, repetitive, and reliable terminology to describe the basic manipulations of the ultrasound transducer. Previously, 5 basic transducer motions have been defined and used in education. However, even with this effort, there is still a lack of consistency and clarity in describing transducer manipulation and motion. In this technical innovation, we describe an expanded definition of transducer motions, which include movements to change the transducer's angle of insonation to the target as well as the location on the body to optimize the ultrasound image. This new terminology may allow for consistent teaching and improved communication in the process of image acquisition.     

Effects of Vein Width and Depth on Ultrasound-Guided Peripheral Intravenous Success Rates

Background: Increasing numbers of operators are learning to use ultrasound to guide peripheral intravenous (i.v.) catheter insertion in patients with difficult access. Unfortunately, failed cutaneous punctures are common. Some veins seen on ultrasound may be better choices than others. Objectives: To estimate the effects of vein width and depth on the probability of success in ultrasound-guided i.v. catheter insertion. Methods: We prospectively collected data from attempts at ultrasound-guided venous catheter insertion between the antecubital fossa and mid-humerus. Each ultrasound machine's ruler function was used to determine depth from the skin to the closest vein edge and that vein's largest diameter. Success was defined as being able to freely withdraw blood or inject saline after the first skin puncture, considering each encounter independently. We calculated relative success rates, confidence intervals, and p values using reference groups selected by histogram analysis. Results: Thirty-five operators recorded 180 encounters; 100 (56%) were successful on the first skin puncture, and 152 (84%) were eventually successful. Success rates were not linearly related to vein width or depth. Success rates were higher for veins with diameter ≥ 0.4 cm vs. those < 0.4 cm (63% [78/124] vs. 39% [22/56], relative success 1.6 [95% confidence interval (CI) 1.1–2.3], p = 0.005) and for veins of depth 0.3–1.5 cm vs. veins of depth < 0.3 or > 1.5 cm (58% [96/165] vs. 27% [4/15], relative success 2.2 [95% CI 0.9–5.1], p = 0.04). Conclusion: Success rates are higher in larger veins (≥ 0.4 cm) and veins at moderate depth (0.3–1.5 cm).