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types of fetal ultrasound

Described below is a very narrow selection of the different types of fetal ultrasound used in obstetrics. This is not a complete list and only serves to help you better understand the use and function of a fetal ultrasound doppler.

I. Doppler Ultrasound (Audio)

Continuous Wave Doppler Fetal Ultrasound
This type of fetal ultrasound uses the change in pitch of the sound waves (doppler effect) to provide information about blood flow through a blood vessel. The doctor listens to the sounds produced by the transducer to evaluate the blood flow through an area that may be blocked or narrowed. This type of ultrasound can be done at the bedside in the hospital to provide a rapid estimate of the extent of blood vessel damage or disease.

This is the type of ultrasound used by your hand-held fetal ultrasound doppler.

II. Imaging Ultrasound (Sonography)

A-Mode Fetal Ultrasound
A-Mode is a one-dimensional display of sound waves. Each time a sound wave hits a structure, a spike is formed on the examiner's screen. The height and spacing between each of the echoes provides the examiner with valuable information. A-Mode scans are now mostly obsolete in medical imaging.

B-Scan Fetal Ultrasound
B-Scan ultrasound is used to create a two-dimensional, cross-section view. Multiple sound waves are emitted from the probe allowing the examiner to visualize structures.

2D Fetal Ultrasound
Traditionally fetal ultrasounds (sonographs) are 2D, providing a two dimensional image. These images are made up of image slices of which only one at a time is visible and creates a flat looking image. A 2D fetal ultrasound (sonograph) can display up to 100 images per second. The 2D is the most common type of sonograph.

3D Fetal Ultrasound
Recently, three dimensional fetal ultrasounds have become more and more common but due to there high expense ($250,000) haven't made there way into all hospitals. The 3D fetal ultrasound takes thousands of slices and digitally stores and shades them to emulate a more life like image of the baby.

4D Fetal Ultrasound
A Four dimensional fetal ultrasound simply means that the images can be seen in real time, allowing for the study of fetal behavior.

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