What to know about a 10-week dating scan

The sonographer measures the pregnancy on ultrasound and may adjust the estimated due date if the measurement differs from the date based on your last menstrual period. The scan can also show whether there is more than one pregnancy. It cannot identify every possible health or developmental concern.

At this stage, an abdominal ultrasound may provide clear images, although a vaginal ultrasound may be offered when a closer view is needed. The scan checks that the pregnancy is within the uterus and compares the embryo's measurement with the expected gestational age.

A result that differs from your expected dates can reflect later ovulation or uncertainty about the last menstrual period. If the findings are unclear, the clinician may arrange another ultrasound rather than drawing a conclusion from a single image.

Follow the clinic's instructions about whether to arrive with a full bladder, because requirements depend on the type of ultrasound. Bring your pregnancy records and the date of your last menstrual period if you know it. Mention bleeding, pelvic pain, previous ectopic pregnancy, fertility treatment, or uncertainty about your dates before the examination.

Ask when and how you will receive the report. Screening for certain chromosomal conditions is separate from basic dating, so confirm which screening choices are available and whether another appointment is needed.

Do not wait for a scheduled scan if you develop vaginal bleeding or persistent pelvic pain; contact your maternity service or an urgent-care clinician for advice. Seek emergency care for severe or sudden abdominal pain, shoulder-tip pain, fainting, marked dizziness, collapse, or heavy bleeding. These features can accompany internal bleeding or another problem needing immediate assessment.

You may wish to ask which due date will be used, whether the pregnancy measurements match the scan dates, and whether any follow-up imaging is recommended. Also clarify what type of screening is being offered, what each test can and cannot show, and whom to contact if bleeding or pain develops after the visit.