Understanding Your Anomaly Scan: A Detailed Look at Your Baby's Development

Hello, expectant parents! As you journey through pregnancy, you'll encounter various important check-ups. One of the most significant is the Anomaly Scan, often called the 20-week scan or Mid-pregnancy scan. This detailed ultrasound examination is a wonderful opportunity to get a closer look at your baby's development and ensure everything is progressing as expected.

At Param Maternity & Surgical Nursing Home, we understand you might have questions about this scan, and we're here to provide clear, reassuring information.

What is an Anomaly Scan?

The Anomaly Scan is a comprehensive ultrasound performed during the second trimester of pregnancy. Its primary purpose is to carefully examine your baby's anatomy, screen for any structural abnormalities (also known as anomalies), and evaluate their growth, the position of the placenta, and the amount of amniotic fluid surrounding them. You might also hear it referred to as a Level II ultrasound, Fetal Morphology Scan, or TIFFA (Targeted Imaging for Fetal Anomalies) scan.

When is the Anomaly Scan Performed?

The ideal time for this detailed scan is typically between 18 and 22 weeks of pregnancy. This window allows your baby to be developed enough for a thorough assessment, while still providing good visibility for the sonographer to examine all the necessary structures. Leading guidelines recommend offering this examination to all pregnant patients during this period.

What Does the Anomaly Scan Look For?

During the Anomaly Scan, our sonographer will carefully examine various parts of your baby's body. Think of it as a detailed health check for your little one, looking at:

• Fetal Head & Brain: Checking the shape of the skull and key brain structures like the cerebellum and ventricles.
• Fetal Face: Assessing the profile, eyes, nasal bone, and the integrity of the upper lip to screen for conditions like cleft lip.
• Fetal Spine: Examining the alignment of the vertebrae and skin coverage to detect neural tube defects such as spina bifida.
• Fetal Chest & Heart: Confirming the presence, position, and size of the heart, and carefully looking at its four chambers and the great arteries to screen for congenital heart defects. The fetal heart rate is also documented.
• Fetal Abdomen & Organs: Visualizing the stomach, kidneys, bladder, and ensuring the abdominal wall is intact where the umbilical cord attaches.
• Fetal Limbs: Checking for the presence and length of bones in the arms, legs, hands, and feet.
• Placenta: Determining its location (e.g., anterior, posterior) and its distance from the cervix.
• Umbilical Cord: Confirming the normal number of vessels (typically two arteries and one vein).
• Amniotic Fluid: Assessing the volume of fluid surrounding your baby.
• Fetal Biometry: Taking measurements like Biparietal Diameter (BPD), Head Circumference (HC), Abdominal Circumference (AC), and Femur Length (FL) to assess your baby's size and growth.

How is the Scan Performed?

The anomaly scan is a straightforward and non-invasive procedure. You'll lie comfortably on an examination couch, and a special gel will be applied to your abdomen. A small handheld device called a transducer will then be gently moved over your skin. This transducer sends sound waves into your womb, which bounce off your baby and create real-time images on a screen.

It's a painless procedure, though you might feel a little pressure as the sonographer works to get the best views. The duration can vary depending on your baby's position and how clearly all structures can be seen.

Is the Anomaly Scan Safe?

Many parents wonder about the safety of ultrasound. Rest assured, diagnostic ultrasound has been used for decades and is considered very safe for both you and your baby. There are no known adverse biological effects from standard diagnostic obstetric ultrasound procedures. Organisations like the RCOG confirm its safety.

What Happens After the Scan?

The results of your anomaly scan can fall into a few categories:

• Normal Findings: If everything looks as expected, you'll receive reassurance, and your routine antenatal care will continue. It's important to remember that while a normal scan is very reassuring, it doesn't guarantee a perfectly healthy baby, as not all conditions can be detected.
• Uncertain or Suboptimal Views: Sometimes, your baby's position or other factors might make it difficult to get clear images of all structures. In such cases, a repeat scan may be recommended, usually within 1-2 weeks.
• Minor Markers ('Soft Markers'): These are findings that are not structural anomalies themselves but might be associated with an increased risk of certain conditions, particularly chromosomal abnormalities. If soft markers are identified, you will receive counseling to discuss their significance, which is often low when isolated. This may lead to a discussion about further diagnostic testing, depending on the specific marker and your individual risk factors.
• Suspected Anomaly: If a major structural anomaly is suspected, you will be referred to a Fetal Medicine Unit or a Maternal-Fetal Medicine (MFM) specialist for a more detailed, tertiary-level scan and further counseling. This follow-up may include:
  • Detailed Ultrasound/Fetal Echocardiogram: To confirm and characterize the suspected anomaly.
  • Genetic Counseling: To discuss the findings, prognosis, and options for further testing.
  • Invasive Diagnostic Testing: Procedures like amniocentesis may be offered to obtain a fetal karyotype or microarray for a definitive diagnosis.
  • Delivery Planning: If an anomaly is confirmed, planning for the timing, mode, and location of birth at a specialized center with appropriate neonatal intensive care (NICU) and pediatric subspecialty support will be crucial.
  • Pregnancy Options Counseling: A discussion of all available options, including continuation of pregnancy or termination of pregnancy, where legally available and in accordance with your wishes.

It's natural to feel anxious if a problem is suspected. Remember, a suspicion doesn't always mean a severe problem, and further investigation is key to understanding the situation fully.

Important Things to Remember: Limitations of the Scan

While the anomaly scan is an incredibly powerful tool, it's important to understand its limitations:

• Not 100% Diagnostic: The scan is a screening tool. It cannot detect every single possible problem or guarantee a perfectly healthy baby. Some conditions might not be visible on ultrasound, or they might develop later in pregnancy.
• False Positives: Sometimes, a finding is suspected but is ultimately found to be absent after further testing, causing unnecessary stress.
• False Negatives: Conversely, an existing anomaly might not be detected by the scan.
• Factors Affecting Quality: Fetal position, maternal body mass index (BMI), and the quality of the equipment can all impact how clearly structures can be seen.

Reducing Risks and Early Detection

While the anomaly scan is about detecting issues, there are steps you can take to promote a healthy pregnancy:

• Folic Acid: Taking folic acid supplements before conception and in early pregnancy significantly reduces the risk of neural tube defects.
• Avoid Teratogens: Steer clear of harmful substances like certain medications, alcohol, illicit drugs, and high doses of radiation.
• Manage Health Conditions: If you have pre-existing conditions like diabetes, ensuring they are well-controlled before and during pregnancy is vital.
• Vaccination: Ensure you are up-to-date on vaccinations, especially against infections like rubella, before pregnancy.

The anomaly scan itself is a key tool for secondary prevention. Its purpose is the early detection of anomalies to enable informed decision-making, prenatal management, and appropriate postnatal care planning.

Prognosis

The prognosis following an anomaly scan is entirely dependent on its findings. A normal scan is highly reassuring, with the vast majority of such pregnancies resulting in a healthy baby. If an anomaly is detected, the outlook varies widely, from conditions that are easily correctable after birth to those with significant long-term implications or those incompatible with life.

We encourage you to discuss any concerns or questions you have with your healthcare provider. They are your best resource for personalized advice and support throughout your pregnancy journey.