Pregnancy Ultrasound

What is an Ultrasound?

Ultrasound (US) imaging is a method of obtaining images of internal organs in the body by sending high-frequency sound waves into the body. The image itself is the sound wave echoes of the ultrasound. As the sound waves bounce against objects, its echoing waves can be used to identify how far away the object is, how large it is, its shape and its internal consistency, be it fluid, solid or mixed. These sound waves are instantly measured and displayed on a computer as a video or still picture.

A benefit of ultrasound is that no ionizing radiation is involved, unlike conventional x-rays. In pregnancy, obstetric ultrasound uses sound waves to visualize and determine the condition of a pregnant woman and her embryo or fetus.

Why Would I Have an Ultrasound?

There are several indications for ultrasound in a pregnant woman including:

• Establishing the presence of a living embryo or fetus
  
• Determine the cause of bleeding in early or mid-late pregnancy
  
• To diagnose any potential congenital abnormalities in the developing embryo or fetus. If birth defects are suspected, your provider will refer you for a more detailed ultrasound examination.
  
• To determine if there are twins or multiple pregnancies
  
• To determine the location, size or possible abnormalities of the placenta.
  
• To estimate the age and size of the fetus. Size of the fetus is important when preterm delivery is being contemplated or when the baby is believed to be late.
  
• To evaluate the position of the fetus and the placenta and to locate the fetus prior to chorionic villus sampling or amniocentesis
  
• Determine the condition of the fetus if no heartbeat has been detected by 14th week or if there has been on fetal movement by week 22.
  
• Locate an IUD that was in place at the time of conception.
  
• Measure the amount of amniotic fluid
  
• Check for fibroids within the uterus.
  
• Detect cervical changes that might predict preterm labor.
  
• Verify breech presentation or other uncommon fetal or cord position before delivery.
  
• Providing valuable information leading to treatment that can improve a woman's chances of having a healthy baby.
  

Preparing For the Ultrasound
Your doctor will explain that you should wear loose fitting clothes for the examination. Only the lower abdominal area needs to be exposed during this procedure, so wear something that can be easily removed. You may be required to have a full bladder because this will push the air-filled bowel out of the way and allow an unobstructed view of the uterus, embryo or fetus to be obtained. You may be instructed to drink up to six glasses of water and avoid urinating during the two hours before the procedure. If you are having the ultrasound later on in your pregnancy, a full bladder is generally not required.