An official website of the United States government
The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you’re on a federal
government site.
The site is secure.
The https:// ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
1 Department of Obstetrics and Gynecology, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
2 Department of Radiology, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
3 Department of Emergency Medicine, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
4 Department of Emergency Medicine, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada; Centre for Health Evaluation and Outcomes Sciences, St Paul's Hospital, Vancouver, BC, Canada.
1 Department of Obstetrics and Gynecology, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
2 Department of Radiology, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
3 Department of Emergency Medicine, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada.
4 Department of Emergency Medicine, St Paul's Hospital and the University of British Columbia, Vancouver, BC, Canada; Centre for Health Evaluation and Outcomes Sciences, St Paul's Hospital, Vancouver, BC, Canada.