The anatomy scan, also known as the Level 2 ultrasound or detailed fetal survey, is a standard procedure performed during the second trimester of pregnancy. This imaging technique uses high-frequency sound waves to create detailed pictures of the developing fetus within the uterus. It offers a thorough look at the baby’s growth and internal structures. This routine prenatal scan provides medical professionals with significant information to support the management of a healthy pregnancy.
The Optimal Timing and Primary Goal
This detailed ultrasound is typically scheduled between 18 and 22 weeks of gestation. This window is optimal because the fetus is large enough for the sonographer to capture detailed images, and there is sufficient amniotic fluid for clear visualization. The primary medical goal of the anatomy scan is to perform a systematic screening of the fetus’s structural development.
The procedure is designed to confirm that the baby’s organs and body systems are forming as expected. It acts as a screening tool to identify or rule out structural conditions that may affect the baby’s health. Assessing the integrity of the fetal structure at this mid-point helps guide necessary planning for specialized care, either during the remainder of the pregnancy or immediately following birth.
What Specific Structures Are Examined
The anatomy scan is a systematic survey involving numerous measurements and images of the entire fetal body. The sonographer first focuses on biometry, which measures specific parts of the body to assess fetal growth and alignment with gestational age. Standard measurements include the head circumference, the abdominal circumference, and the length of the femur bone. These data points help calculate an estimated fetal weight.
A comprehensive inspection of the major organ systems is then performed, starting with the brain and spine. The sonographer checks the structure of the cerebral ventricles and cerebellum, and evaluates the spine longitudinally and in cross-section to confirm the vertebrae are properly aligned and covered by skin. Particular attention is given to the four chambers of the heart, its valves, and the major blood vessels, as congenital heart defects are among the most common structural conditions.
The abdominal organs are also examined. The sonographer ensures the stomach bubble is visible, which indicates the baby is swallowing amniotic fluid. The presence and function of both kidneys and the bladder are confirmed, along with a check of the abdominal wall to ensure all internal organs are contained.
External Features
Beyond the internal structures, the scan evaluates the external features. This includes the facial profile to look for conditions like cleft lip, and a detailed assessment of the four limbs, including hands and feet.
Finally, the scan assesses the environment surrounding the fetus, including the placenta and umbilical cord. The location of the placenta is documented to identify conditions like placenta previa. The umbilical cord is inspected to confirm it contains the expected three vessels—two arteries and one vein. The volume of amniotic fluid is measured, as abnormal levels can indicate potential issues with fetal swallowing or kidney function.
Preparing for the Appointment and What to Expect
An anatomy scan appointment often lasts between 30 and 60 minutes, depending on the baby’s position and cooperation. Preparation instructions vary, but many clinics request the pregnant person arrive with a moderately full bladder. A full bladder can help push the uterus higher in the abdomen, which may improve the clarity of the ultrasound images.
During the procedure, the pregnant person lies on an exam table, and a clear, water-soluble gel is applied to the abdomen. The sonographer moves a handheld transducer across the skin, using gentle pressure to capture the necessary images. The transducer emits sound waves that bounce off the baby’s tissues and are translated into a live image on the screen. The sonographer may ask the patient to shift positions or cough to encourage the baby to move if a particular structure is difficult to visualize.
Interpreting Results and Subsequent Care
In many cases, the sonographer can provide immediate reassurance that all required images have been successfully captured. A formal, detailed report is then compiled by a physician, such as a maternal-fetal medicine specialist or a radiologist, who interprets the images and measurements. The results are typically communicated to the referring obstetric provider, who then discusses the findings with the patient.
If the scan is inconclusive, perhaps because the baby was not in an ideal position, a repeat scan may be scheduled a week or two later. If a finding is noted that requires further evaluation, the patient is often referred for specialized testing. This might include:
- A targeted Level 3 ultrasound.
- A fetal echocardiogram for a more detailed look at the heart.
- Genetic counseling.
Not all findings indicate a severe problem, as some observed variations are considered “soft markers” that may resolve or be harmless. Early detection of any anomaly allows the medical team and the family to create a proactive management plan. This plan could involve consulting with pediatric specialists to prepare for any specialized care the baby may need after delivery.