Your first ultrasound: what you can see and when the heartbeat shows

For many people the first ultrasound is the moment a pregnancy becomes real: seeing a tiny flickering dot on the screen can bring excitement and relief. It can also carry a little nervousness, which is perfectly natural.

When is the first ultrasound done?

An early pregnancy ultrasound is usually done between weeks 6 and 10. Your doctor may choose a slightly earlier or later date depending on your situation. It is not essential in every pregnancy, but it is a common way to confirm the pregnancy's age and location.

What does it look at?

• Gestational sac: shows whether the pregnancy has settled in the womb.
• Yolk sac: a small ring-shaped structure that accompanies your baby's feeding in the first weeks.
• Embryo and crown-rump length: your baby's length is measured, which can help pin down the gestational age and due date.
• Heartbeat: seen as a tiny flicker of movement.
• Number of babies: one or more.
• Womb and ovaries: their general appearance is checked.

When can the heartbeat be seen?

In most pregnancies a heartbeat starts to be visible around week 6. If it is not yet seen on a very early scan, that is not a bad sign in itself; dates can be a few days off, ovulation may have been later than assumed, or the equipment may play a part. In that case your doctor usually suggests looking again after a week or two.

Abdominal or vaginal?

In the early weeks your baby is so small that a vaginal (transvaginal) scan is often used because it gives a clearer picture. It can feel a little uncomfortable but is usually not painful. For an abdominal scan, a fuller bladder can sometimes improve the image, and your doctor will tell you. Used appropriately and when needed, ultrasound is regarded as safe by international bodies.

Why can the date change?

There may be a difference of a few days between the week calculated from your last period and the ultrasound measurement. Depending on the size of the gap, your doctor will either set the due date by ultrasound or leave it as it is. This is very common and nothing to worry about.

What you can do

• Have the date of your last period ready.
• Follow any instructions about your bladder.
• You can bring someone with you.
• It is very common not to understand the picture at first glance; just ask what you are looking at.
• If the result is not what you hoped for, please do not blame yourself; most early pregnancy losses have nothing to do with anything done or not done.

When to contact your doctor

Do not wait for the scan appointment if you notice:

• Vaginal bleeding, especially clots or heavy bleeding
• One-sided or severe abdominal or shoulder pain
• Sudden weakness, dizziness or fainting
• Fever or foul-smelling discharge

If you have severe pain, fainting or heavy bleeding, call 112; conditions such as an ectopic pregnancy can need urgent assessment. This article is for information only; your doctor decides the right timing and method for you.