Fetal well being or growth scan
This scan is essentially for after 26 weeks of pregnancy.
There has been a lot of discussion in the press over the years about how small babies are more prone to stillbirth. However, a lot
of the research shows that simply measuring the pregnant abdomen with a tape measure is not an accurate manner in which to detect
small babies and over half are missed by using this technique. Ultrasound is a more reliable method of accurately assessing expected
birthweight in pregnancy when performed after 28 weeks.
What must be remembered though is that having a small baby is not necessarily a danger to the life or wellbeing of the baby as long as
there is no evidence of placental failure. This is what we check for carefully with our scan.
We have scanned thousands of babies over the years and to date have not had one stillbirth notified to us that could have been
prevented due to the small size of the baby. If your baby is found to have problems on the scan with growth, you will be referred back to
your hospital for subsequent management.
With this in mind, the purpose of our fetal wellbeing ultrasound scan is to assess:
- Size of the baby
- Placental resistance to blood flow ie how the placenta is working
- Amount of fluid surrounding the baby
- Position of the baby
- Baby's current state of health
We check the position of the baby even though most are head down towards the end of pregnancy. Occasionally (4% at 37 weeks), the baby can be in a breech position. A breech is where the bottom is closest to the cervix (opening to the uterus) and as such is a different management to a head first baby. 50% of breech babies are not diagnosed until someone is in labour as it is very hard to detect if they are head or bottom first in many instances by just palpating the abdomen. This is an important management issue when dealing with home births in particular as most women elect for an elective Caesarean section rather than a vaginal breech birth.
The age of the baby is established in early pregnancy. The size of the baby can be compared with the size expected for this stage of pregnancy, giving information about the baby's growth. An estimate of the weight can be calculated from the measurements.
The resistance to blood flow in the placenta is assessed with Doppler ultrasound of the umbilical artery. The placental function is also assessed by meausuring the fluid around baby within the womb. This however, is not as accurate as using the Doppler flow method.
The modified biophysical profile examines fetal body movement, breathing movement, tone, and amniotic fluid volume. This will give indication of fetal well being at the time of the scan and again provide reassurance when all is normal.
