What is Transcranial Doppler (TCD) Bubble Study?

A Transcranial Doppler (TCD) bubble study is a medical diagnostic procedure that uses ultrasound to examine the blood flow in the arteries and veins within the brain.

After injecting a small amount of bubbles into a vein in the arm, an ultrasound probe (positioned on the head) utilizes sound waves to detect the presence of these bubbles traversing the brain arteries. Normally, these injected bubbles are trapped within the lung and do not appear in the brain arteries. In patients with an abnormal connection between the arteries and the veins (especially those with a defect within the heart), these bubbles bypass the filtration effect of the lung and travel towards the brain. Finding these abnormalities are of particularly importance for patients who had experienced a stroke event; as such defects may predict a higher recurrence of stroke. Moreover, there are effective treatment options available to help patients.

How should I prepare for the test?

You may continue with your regular diet and medications. No fasting is required for the test. This test is safe. However, some patients may experience discomfort or infection at the area where the IV is inserted. Complications can occur but are rare:

  • Approximately 1 to 2 patients per 1,000 cases (0.15%) may encounter a stroke or transient ischemic attack (mini-stroke).
  • Instances of blood clots in the lungs are extremely rare

Hence, it is important to inform the doctor promptly if any discomfort arises. You should reschedule for the test if you are feeling unwell e.g. fever, cough.

What happen during the test?

This test is conducted by a doctor and a sonographer and will take about 30 to 45minutes to complete.

  • It is performed while you are in a reclined position
  • An intravenous line (IV) is carefully inserted into a blood vessel in your arm
  • A small amount of water based gel is applied to your scalp, and a headset is fitted
  • Subsequently, a saline solution containing minuscule bubbles is injected into your blood vessel via the IV. You may experience slight discomfort but there should be no pain. However, should any pain arise, please inform the doctor or staff
  • The headset monitors if any of the tiny bubbles reach your brain arteries
  • After completion, the headset and IV are removed, and the gel is cleaned off
  • The final report will be sent to your doctor, who will discuss the results with you during your next appointment