- 1First trimester ultrasound is recommended for assessment of threatened abortion to document fetal viability (II-2B) or for incomplete abortion to identify retained products of conception (II-2B).
- 2First trimester ultrasound is not recommended to diagnose pregnancy but is recommended to date a pregnancy (ideally at 7–12 weeks). If menstrual dating is reliable and an early comprehensive pregnancy ultrasound (11–14 weeks) is planned, dating should be confirmed concurrently with this exam (III-A).
- 3First trimester ultrasound is recommended prior to pregnancy termination (II-2B).
- 4First trimester ultrasound is recommended during diagnostic or therapeutic procedures requiring visual guidance (e.g., chorionic villus sampling) and prior to prophylactic cervical cerclage placement (I-A).
- 5First trimester ultrasound is recommended for suspected multiple gestation to allow for reliable determination of chorionicity and amnionicity and to establish early fetal genetic and anatomic screening (II-2A).
- 6First trimester ultrasound is recommended in the workup for suspected ectopic pregnancy, molar pregnancy, and suspected pelvic masses (II-1A).
- 7Basic fetal anatomy should be reviewed whenever obstetric ultrasound is done at 11–14 weeks, while women at increased risk of fetal structural and genetic abnormalities can be offered enhanced screening, if performed by ultrasound providers with appropriate imaging expertise (II-3C).
- 8Nuchal translucency screening should be offered as part of a prenatal genetic screening and counselling program by experienced operators with appropriate quality assurance processes in place. Any patient with a nuchal translucency greater than 3.5 should be offered referral to maternal-fetal medicine (II-2A).
- 9When appropriate expertise and resources are in place to screen women for the risk of preeclampsia, first trimester ultrasound is recommended as a valuable component of the screening protocol (I-A).
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This document reflects emerging clinical and scientific advances on the date issued and is subject to change. The information should not be construed as dictating an exclusive course of treatment or procedure to be followed. Local institutions can dictate amendments to these opinions. They should be well documented if modified at the local level. None of these contents may be reproduced in any form without prior written permission of the publisher.
All people have the right and responsibility to make informed decisions about their care in partnership with their health care providers. In order to facilitate informed choice, patients should be provided with information and support that is evidence-based, culturally appropriate and tailored to their needs.
This guideline was written using language that places women at the centre of care. That said, the SOGC is committed to respecting the rights of all people - including transgender, gender non-binary, and intersex people - for whom the guideline may apply. We encourage healthcare providers to engage in respectful conversation with patients regarding their gender identity as a critical part of providing safe and appropriate care. The values, beliefs and individual needs of each patient and their family should be sought and the final decision about the care and treatment options chosen by the patient should be respected.