• Fasting: No fasting is required. In fact, eating a light meal or a healthy snack about an hour before your scan is highly encouraged, as the natural sugar boost often helps the baby wake and move.
• Hydration: Depending on your stage of pregnancy, you may be asked to drink 1–2 glasses of water before the test. In the third trimester, a completely full bladder is usually unnecessary because the baby and amniotic fluid provide ample visibility.
• Clothing: Wear comfortable, loose, two-piece clothing (such as a top and skirt/trousers) so you can easily expose your abdomen without undressing completely.

During the scan, the doctor focuses on three primary vascular systems to get a complete picture of the baby’s health:

Key areas evaluated during the scan include:

• The Umbilical Artery: Measures the blood flowing from the baby back to the placenta. Healthy flow should face low resistance. If resistance is high, it means the placenta is struggling.
• The Fetal Middle Cerebral Artery (MCA): Measures blood flow inside the baby’s brain. If a baby feels oxygen-deprived or is anemic, their body will naturally redirect blood away from other organs straight to the brain, a protective mechanism known as the brain-sparing effect. The Doppler catches this shift instantly.
• The Maternal Uterine Arteries: Evaluates the main blood vessels supplying the uterus to assess the mother’s risk of developing preeclampsia later in the pregnancy.
• The Ductus Venosus: A tiny vein inside the baby’s liver that is checked in advanced cases to evaluate how well the baby’s heart is handling the blood flow pressure.