Obstetric Ultrasonography

Obstetric ultrasonography, also known as obstetric ultrasound or prenatal ultrasound, is a non-invasive medical imaging technique used to visualize the fetus and placenta during pregnancy.

Purpose

The primary purpose of obstetric ultrasonography is to:

• Confirm pregnancy and detect fetal heartbeat
• Determine gestational age and due date
• Monitor fetal growth and development
• Detect potential fetal abnormalities or complications
• Guide invasive procedures, such as amniocentesis or chorionic villus sampling (CVS)

Types of Obstetric Ultrasonography

There are several types of obstetric ultrasonography, including:

• Transabdominal ultrasound: performed through the abdomen using a transducer
• Transvaginal ultrasound: performed through the vagina using a transducer
• Doppler ultrasound: uses sound waves to measure blood flow and detect potential complications, such as placental insufficiency
• 3D and 4D ultrasound: provides detailed images of the fetus in three dimensions, allowing for better visualization of fetal anatomy

Procedure

The procedure typically involves:

• A full bladder to help visualize the uterus and fetus
• A gel or lubricant applied to the skin to facilitate sound wave transmission
• A transducer moved over the abdomen or inserted into the vagina to capture images
• Images displayed on a monitor for interpretation by a healthcare provider

Risks and Limitations

Obstetric ultrasonography is generally considered safe, but there are some risks and limitations to be aware of:

• No established risk: the American Institute of Ultrasound in Medicine (AIUM) states that there is no established risk associated with obstetric ultrasonography
• Operator dependence: the accuracy of the procedure depends on the skill and experience of the operator
• Limited visualization: certain fetal structures or abnormalities may not be visible using ultrasonography

Indications and Guidelines

The American College of Obstetricians and Gynecologists (ACOG) recommends obstetric ultrasonography for:

• Confirmation of pregnancy: between 5-6 weeks gestation
• Dating ultrasound: between 7-10 weeks gestation
• Anatomy survey: between 16-22 weeks gestation
• Growth restriction monitoring: as needed, based on individual patient risk factors