Do emergency physicians use serum D-dimer effectively to determine the need for CT when evaluating patients for pulmonary embolism? Review of 5,344 consecutive patients.

OBJECTIVE: The purpose of our study was to investigate whether D-dimer screening is being used effectively to determine the need for MDCT in diagnosing acute pulmonary embolism (PE) in emergency department patients. MATERIALS AND METHODS: We performed a retrospective review of all patients who underwent D-dimer testing or MDCT in the emergency department from January 1, 2003, through October 31, 2005. A D-dimer value of > 0.43 microg/mL was considered positive. Diagnosis of PE was made on the basis of the MDCT. Clinical algorithms for diagnosing PE mandate that patients with a low clinical suspicion for PE undergo D-dimer testing, then MDCT if positive. For patients with a high clinical suspicion for PE, MDCT should be performed without D-dimer testing. RESULTS: Of 3,716 D-dimer tests, 1,431 (39%) were positive and 2,285 (61%) were negative. MDCT was performed in 166 (7%) patients with negative D-dimer results and in 826 (58%) patients with positive D-dimer results. The prevalence of PE in patients with a high clinical suspicion and no D-dimer testing was 9% (139/1,628), which was higher than the rate of PE in the positive D-dimer group at 2% (19/826) (p < 0.0001). There was no significant difference in the prevalence of PE in the positive and negative D-dimer groups (2% vs 0.6%, respectively) (p = 0.23). The sensitivity and negative predictive value of D-dimer for PE were 95% (95% CI, 73.1-99.7%) and 99% (95% CI, 96.2-99.9%), respectively. CONCLUSION: D-dimer screening is not used according to established diagnostic algorithms to determine the need for MDCT in diagnosing acute pulmonary embolism in our emergency department.

Utilization patterns and diagnostic yield of 3421 consecutive multidetector row computed tomography pulmonary angiograms in a busy emergency department.

OBJECTIVE: To compare examination volume and diagnostic yield of computed tomography (CT) pulmonary angiography (CTPA) and ventilation-perfusion (V/Q) scintigraphy for detection of suspected pulmonary embolism (PE) in emergency department patients. METHODS: Every CTPA and V/Q scan result for emergency department patients between October 2001 and September 2005 were reviewed. Patients with prior PE and follow-up examinations were excluded. RESULTS: A total of 3421 CTPA examinations and 198 V/Q scans met inclusion criteria. Average CTPA examinations completed per month increased 227%, from 33.4 to 109.2 for the first and last 24-month periods, respectively. Ventilation-perfusion scintigraphy volume decreased 80% (from 6.9 to 1.4 per month). Total diagnoses of PE per month increased 89% from 4.0 to 7.5, whereas the percentage of positive CTPA examinations dropped from 9.8% to 6.8%. CONCLUSIONS: Availability of CT in the emergency department and lower physician thresholds for test utilization have increased the use of CT pulmonary angiography and increased detection of PE.

Cricoid cartilage on sonography in pediatric patients mimics a thyroid mass.

OBJECTIVE: The purpose of this study was to describe the sonographic appearance of the uncalcified cricoid cartilage in pediatric patients and illustrate how this can be easily confused with a thyroid mass or residual thyroid tissue after thyroidectomy. METHODS: We retrospectively reviewed the sonographic and computed tomographic examinations performed on 4 adolescent patients. Two patients had either thyroid cancer or thyroid nodules, and 2 healthy patients were reviewed to show normal anatomy. Results were compared with the clinical and surgical findings in each patient. RESULTS: Computed tomographic and sonographic examinations showed the normal anatomic relationships and imaging appearance of the cricoid cartilage. Findings from a follow-up sonographic examination on a patient with treated thyroid cancer were initially interpreted as residual thyroid tissue, but another examination revealed that this tissue was actually uncalcified cricoid cartilage. Another patient who had intraoperative sonography verified these findings. CONCLUSIONS: Uncalcified cricoid cartilage in a pediatric patient appears on sagittal sonography as a round or ovoid structure with variable echogenicity, located posteromedial to the thyroid gland. Awareness of this structure's sonographic appearance should prevent unnecessary biopsy or surgery.