At 5 weeks into pregnancy things are so small there is very little to see on ultrasound. Even at 6 weeks it can be difficult to see an embryo with some people.
The image above shows a 5 week + pregnancy, but it won't always be this clear for all people. We say 5 weeks plus because without being able to measure the embryo, we can only measure the mean sac diameter which is a combination of 3 measurements of the sac to gather an approximate date, but it isn't as accurate and measuring the embryo. At this point we can see the dark area with a small circle inside. The dark area is the gestation sac and the small white circle is called a yolk sac. The job of the yolk sac is to provide the growing embryo with nutrients until the placenta takes over later on into pregnancy. With only a yolk sac to see, we can confirm that the pregnancy is in the right place or not ectopic.
The image above is now showing a 6 week pregnancy at this point it is possible to see the embryo and measure the gestational age quite well, but it is not always possible to see a heartbeat at this time. If the heartbeat is not visible it can cause a lot of worry waiting to scanned again in a week or so time so it's always best to avoid this situation from occurring. This is why, at Early Life Ultrasound centre we offer early pregnancy scans from 7 weeks.
In this image the embryo is now 7 weeks measures approximately 10mm from head to bottom or crown to rump. There is a yolk sac but it can't be seen in this particular image. It is normally possible to trace a heartbeat at this stage, which is why we tend to offer early pregnancy scans at this time. It can can avoid the worry and stress of having wait to be re-scanned if all that needs to be seen cannot be seen in one scan appointment.
There is a however here... Because of the variability in cycle lengths cycle lengths are normally estimated at 28 days but can range from 21 to 35 days. If your cycle is longer then you could be a little less pregnant than 7 weeks on the other hand you could be further along if you have a shorter cycle. If we aim for 7 weeks then most of the time we should see all that needs to be seen in one appointment. It does seem like a long wait to see your baby particularly with the sensitivity of today's pregnancy tests letting us know we are pregnant so early on, but it is worth it.
It is important to remember that if you are experiencing bleeding and/or pain then it is always important to rule out an ectopic pregnancy. A visit to the early pregnancy assessment unit may be in order. There, they can scan and obtain quantitative Beta hCG (pregnancy hormone) measurements that combined with a scan can offer further information, but again, it may be that watching and waiting that would be the appropriate course of action. More on ectopic pregnancy later.....
Take a look at the below blog to see more images at different stages.
Another informative read - https://www.earlylife.co.uk/blogs/news/what-is-an-ectopic-pregnancy