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Am J Emerg Med. 2012 Oct;30(8):1627-9. doi: 10.1016/j.ajem.2011.12.002. Epub 2012 Feb 4.

Accuracy of emergency physicians using ultrasound measurement of crown-rump length to estimate gestational age in pregnant females.

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Department of Emergency Medicine, Alameda County Medical Center, Oakland, CA 94602, USA.



The objective of this study is to evaluate the accuracy of emergency providers (EPs) of various levels of training in determination of gestational age (GA) in pregnant patients using bedside ultrasound measurement of crown-rump length (CRL).


We conducted a prospective, cross-sectional, observational study of patients in obstetrical care at an urban county hospital. We enrolled a convenience sample of women at 6 to 14 weeks gestation as estimated by last menstrual period. Emergency providers used ultrasound to measure the CRL. Repeat CRL measurements were performed by either an obstetrical ultrasound technician or senior obstetrician and used as the criterion standard for true GA (TGA).


One hundred five patients were evaluated by 20 providers of various levels of training. The average time required to complete the CRL measurement was 85 seconds. When CRL measurements performed by EPs were compared with the TGAs, the average correlation was 0.935 (0.911-0.959). Using standard accepted variance for CRL measurements at different GAs according to the obstetrics literature (±3 days for 42-70 days and ±5 days for 70-90 days), correlation between EP ultrasound and measured TGA was 0.947 (0.927-0.967).


Emergency providers can quickly and accurately determine GA in first-trimester pregnancies using bedside ultrasound to calculate the CRL. Emergency providers should consider using ultrasound to calculate the CRL in patients with first-trimester bleeding or pain because this estimated GA may serve as a valuable data point for the future care of that pregnancy.

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