CJEM Articles: ultrasonography

Objective: Our goal was to gain a better understanding of the femoral vessel anatomy as it relates to central venous cannulation. The primary objective of this study was to use bedside ultrasonography to determine the amount of exposed femoral vein at three sites corresponding to surface anatomy of the landmark-based procedure.
Methods: This cross-sectional study enrolled a random sample of 180 adult patients presenting to a large urban academic emergency department. Subjects underwent standardized ultrasonography to identify and measure the depth and diameter of the femoral vessels and amount of exposed femoral vein at the level of the inguinal ligament (0 cm) 2 cm and 4 cm below. Repeated measures analysis of variance was used to determine significant relationships between vessel measurements and distance from the inguinal ligament.
Results: The median age was 44.5 (range 19–90) years; 101 patients were male. The mean (± SD) percentage of exposed vein at the inguinal ligament was 83% (± 21). This decreased significantly (p < 0.01) with increasing distance from the inguinal ligament: 65% (± 25) at 2 cm and 56% (± 30) at 4 cm. At every distance away from the inguinal ligament, there were some subjects with no vein exposed.
Conclusion: This study demonstrates significant overlap of the femoral vessels at sites where landmark-based femoral vein cannulation is often attempted. Our results suggest that ultrasound guidance would be beneficial as femoral vein cannulation may be difficult or impossible in certain individuals owing to anatomic variations.

Objective: Computed tomography (CT) is an imaging modality used to detect renal stones. However, there is concern about the lifetime cumulative radiation exposure attributed to CT. Ultrasonography (US) has been used to diagnose urolithiasis, thereby avoiding radiation exposure. The objective of this study was to determine the ability of US to identify renal colic patients with a low risk of requiring urologic intervention within 90 days of their initial emergency department (ED) visit.

Methods: We completed a retrospective medical record review for all adult patients who underwent ED-ordered renal US for suspected urolithiasis over a 1-year period. Independent, double data extraction was performed for all imaging reports and US results were categorized as “normal,” “suggestive of ureterolithiasis,” “ureteric stone seen” or “disease unrelated to urolithiasis.” Charts were reviewed to determine how many patients underwent subsequent CT and urologic intervention.

Results: Of the 817 renal US procedures ordered for suspected urolithiasis during the study period, the results of 352 (43.2%) were classified as normal, and only 2 (0.6%) of these patients required urologic intervention. The results of 177 (21.7%) renal US procedures were suggestive of ureterolithiasis. Of these, 12 (6.8%) patients required urologic intervention. Of the 241 (29.5%) patients who had a ureteric stone seen on US, 15 (6.2%) required urologic intervention. The rate of urologic intervention was significantly lower in those with normal results on US (p < 0.001) than in those with abnormal results on US.

Conclusion: A normal result on renal US predicts a low likelihood for urologic intervention within 90 days for adult ED patients with suspected urolithiasis.

Objective: Emergency department targeted ultrasonography (EDTU) offers the possibility of rapid exclusion of ectopic pregnancy in patients with first-trimester pelvic pain or bleeding. We sought to systematically review the evidence describing the diagnostic accuracy and clinical utility of EDTU in the first trimester of pregnancy, and to generate a pooled estimate of the sensitivity and specificity of EDTU for the detection of intrauterine pregnancy (IUP).

Methods: The literature search, abstract review and study selection were performed using predefined criteria. We abstracted the sensitivity and specificity of EDTU for IUP from included studies, and evaluated and summarized the evidence assessing the effect of EDTU use on time to diagnosis, time to treatment of ectopic pregnancy, emergency department (ED) length of stay and health care costs.

Results: The specificity of EDTU for IUP in most studies exceeds 98%. The sensitivity in most studies exceeds 90%. Pooled estimates were not calculated because of statistical heterogeneity between studies. Published evidence indicates that EDTU use reduces the frequency of missed ectopic pregnancies, decreases time to surgery for ectopic pregnancy, shortens the length of stay for patients with normal pregnancies and may be more cost-effective than diagnostic strategies requiring formal ultrasonography.

Conclusion: EDTU is highly specific for the identification of IUP. Patients who have an IUP identified with EDTU may be safely discharged from the ED with outpatient follow-up. The specificity of EDTU for IUP, along with the potential improvements in patient care that EDTU affords, justifies its adoption as routine ED care in evaluating first-trimester pain or bleeding.