My doctor has recommended a doppler study. How is this test done, and what are they looking for? What do the results mean?
What is a doppler study?
A doppler study is a type of ultrasound that can estimate blood flow through your blood vessels. A regular ultrasound usually shows in shades of grey or sepia tones. When the technician turns on the doppler, you may see red and blue. This may be done routinely as part of a growth ultrasound or biophysical profile. It may also be ordered if your doctor has noticed something concerning in you or baby.
What is a uterine artery doppler study?
During early pregnancy, your doctor may order a doppler study to see how well blood is flowing through the two main uterine arteries. With this test, they look for something called "notching", or high pulsatility. It can be a risk factor for preeclampsia and intrauterine growth restriction (IUGR), but is not a sure prediction. Around 60% of cases who have notching before 20 weeks will go on to have uncomplicated pregnancies. It is a little more concerning if you still have notching after 20 weeks, especially if it is there beyond 24 weeks. If you have high pulsatility or notching in early pregnancy, your doctor may decide to classify you as a high-risk patient. This does not mean you will definitely have complications. It just means they will monitor you a little closer than a standard patient. That way if you do have any issues, they will be found quickly so you can make decisions about your care.
What about an umbilical cord flow study?
This test looks at blood flow through the three main blood vessels in the umbilical cord. There is a range to the umbilical cord flow. Normally, blood should always be flowing strongly through the cord. It flows a little stronger when your heart beats and a little less when your heart is at rest between beats, but always strongly flowing. When the flow first starts to be compromised, it might be described as high resistance. Think of putting your thumb partly over the end of a garden hose. The water still flows, but since the space it is flowing through is narrower, it flows with more force.If it gets worse, you might get reduced flow. This means it is still flowing strongly when your heart beats, but flowing less than it should when your heart is between beats. This is followed by intermittent flow, where it is sometimes flowing between beats and sometimes comes to a stop. After this comes absent flow, sometimes called absent end diastolic flow, when it is no longer flowing between beats. The final stage is reverse flow, when it actually starts flowing the wrong way, away from baby, between beats.What they do about it depends on how bad it is and how far along you are. There is no real treatment, just monitoring and eventually delivery. For someone who is very early on, they watch closely, possibly admitting you to the hospital, until it starts to reverse. Reverse flow usually means delivery very soon after it is discovered. For someone in the late-preterm stage, after 34 weeks, they may go ahead and deliver at the absent stage rather than waiting for reverse. And after 37 weeks, they may move forward for intermittent or even reduced flow.You can ask your doctor to explain the results of this test and what they mean in your case. They should tell you what degree of flow they found. They can also explain how you and baby will be monitored going forward, and at what point they might consider delivery. If you are being monitored outpatient with frequent appointments, be sure to ask about symptoms to watch for between appointments and what to do if you notice something. Kick counts are an important home monitoring tool when there are concerns with umbilical cord flow. The goal is not to reach a minimum number of movements in a timeframe; rather, you want to become familiar with your baby's movement pattern, times of day when they are usually active or resting, and how active they usually are. If you notice changes to this pattern, you should call your doctor or go to the hospital for evaluation.