Uterine arteries

The uterine arteries are the vessels that carry blood to the womb (uterus). Every woman has two uterine arteries, one on each side of the womb. A good blood flow in these arteries helps the placenta to develop normally and helps the baby to grow healthily.

Uterine artery doppler ultrasound

Ultrasound scans use sound waves to look below the skin.

Colour Doppler is a type of ultrasound that can be used to check the blood flow in the uterine arteries. It checks to see if blood is flowing easily (low resistance) or is having to work harder to flow (high resistance).

This is done at the same time as the routine anomaly scan at around 18 to 21 weeks of pregnancy.

What the results mean

Low-resistance blood flow

About 90 in 100 women will have a ‘low-resistance’ blood flow. This means that a normal amount of blood is reaching the baby to help it continue to grow. It also means there is a lower chance of developing pre-eclampsia in this pregnancy.

High-resistance blood flow

About 10 in 100 women will have a ‘high-resistance’ blood flow. 
This means that there is:

  • a slightly increased chance of having a baby that does not grow as well as expected
  • a slightly increased chance of the mother developing high blood pressure or pre-eclampsia in this pregnancy. 

Even so, it is important to remember that most pregnancies with high-resistance blood flow do not develop these problems. It does not mean that your baby will be small or you will develop high blood pressure or pre-eclampsia, only that it is more likely to happen.

If you have high-resistance

Close monitoring

If the doppler does show you have high-resistance blood flow, we will recommend monitoring your pregnancy more closely.

  • We will recommend extra ultrasound scans to monitor the growth of your baby and the blood flow through your baby's umbilical cord and to your baby's brain. These scans will usually be at 28 and 36 weeks. 
  • We will also measure your blood pressure and check your urine at every appointment. 

If your baby is smaller than expected or their blood flow is abnormal at 28 or 36 weeks, or your blood pressure becomes abnormal, we will adjust your care to help keep you and your baby well.

Giving birth

If you have high-resistance blood flow, we recommend that you have an induction of labour between 39+5 and 40+5 weeks, if you have not gone into labour naturally by this point. This is because there is a small increased chance that the placenta will not function as well after 41 weeks.

Your midwife or obstetrician will discuss this with you. We also have more information about induction on our website.

FAQs

If you smoke, it is extremely important that you try to stop. Smoking can affect your baby’s growth and how well your placenta functions. Your midwife can refer you to our stop smoking service.

Monitoring your baby’s movements is a good way for you to check your baby’s wellbeing.

Having high resistance Doppler readings is not an illness and so no effective treatment is recommended.

Having high resistance blood flow in this pregnancy does not increase the chances of having this again in future pregnancies.

Contact information

Kingston Maternity

Contact your named midwife / team or obstetrician if you have any further questions about your scan or the results. 

If you have any urgent questions, you can call the Screening Midwife team on 020 8934 6440.

Email: krft.maternity@nhs.net