The anatomy scan is a comprehensive ultrasound examination performed during pregnancy. It offers a detailed view of the developing fetus, assessing various structures and overall growth. This routine check-up uses sound waves to create images.
Purpose and Timing
The anatomy scan serves as a detailed screening tool to evaluate fetal development, growth, and placental position. It aims to ensure expected development and identify potential structural differences early. While it provides reassurance, it is a screening test and not a definitive diagnostic tool.
This scan is typically performed between 18 and 22 weeks of pregnancy, often called the 20-week ultrasound. This timing is optimal because the fetus has grown sufficiently for detailed anatomical viewing, allowing time for potential interventions or further assessments if concerns arise. Prior to 18 weeks, fetal organs might be too small for thorough evaluation.
What the Scan Examines
During the anatomy scan, the sonographer meticulously examines various anatomical structures and systems of the fetus. This detailed assessment provides a comprehensive overview of development.
The head and brain are assessed, including skull shape and size, cerebral ventricles, and cerebellum. The sonographer also examines brain fluid and anatomical landmarks indicating healthy development. The face is checked for its profile and features like the lips, to identify potential differences such as a cleft lip.
The spine is examined along its full length to ensure proper vertebral alignment and complete skin coverage of the spinal cord. The heart is another primary focus, with the sonographer evaluating its four chambers, major blood vessels, and the fetal heart rate (typically 120 to 180 beats per minute).
Within the abdomen, the scan assesses organs like the stomach, kidneys, bladder, and bowel, checking for their presence, normal structure, and correct positioning. The abdominal wall and diaphragm are also reviewed. Limbs, including arms, legs, hands, and feet, are examined for proper development; fingers and toes can be counted.
Beyond fetal anatomy, the scan also evaluates other aspects of the pregnancy. The umbilical cord is checked for three vessels (two arteries and one vein) and proper insertion. Amniotic fluid volume is measured, and the placenta’s location and appearance are assessed, including its position relative to the cervix.
The Anatomy Scan Experience
While some earlier ultrasounds may require a full bladder, many providers for the 20-week scan suggest an empty bladder for better visualization. The appointment typically lasts 30 minutes to an hour, though it can take longer if the fetus is in a position that makes obtaining clear images difficult.
During the scan, you will lie on an examination table. The sonographer applies gel to your abdomen, then moves a handheld transducer across your skin. You might feel pressure from the transducer as the sonographer captures necessary views and measurements.
The sonographer often remains focused on taking measurements and capturing images. You may see the fetus on screen and sometimes hear the heartbeat. If the fetus is not in an ideal position, the sonographer might ask you to change positions or take a short walk to encourage movement.
Understanding Your Results
After the anatomy scan, the sonographer typically sends images and preliminary findings to your healthcare provider for review. If the scan shows normal fetal development, you will typically continue with routine prenatal care.
Should the scan identify potential concerns or findings requiring further investigation, your healthcare provider will discuss these with you. An initial finding does not always mean a definitive diagnosis; it might lead to recommendations for additional testing, such as follow-up ultrasounds, genetic testing, or specialist consultations. This allows for thorough evaluation to confirm or rule out conditions. Results are usually communicated by your obstetrician or another healthcare provider, either immediately after the scan or at a follow-up appointment.