The 20-week anatomy scan represents a significant milestone for expectant parents, often accompanied by a mix of anticipation and apprehension. This routine prenatal examination is a detailed look at the developing fetus, designed to provide reassurance about its well-being, growth, and internal structures.
The Scan’s Purpose
The 20-week anatomy scan, sometimes referred to as the mid-pregnancy or anomaly scan, is a comprehensive ultrasound examination performed between 18 and 22 weeks of gestation to assess the baby’s development. The primary goal is to visualize and evaluate various aspects of the fetal anatomy, ensuring proper formation.
During this scan, sonographers examine the baby’s major organs, including the heart, brain, kidneys, and spine. They also check the limbs and facial features like the lip. Beyond the baby, the scan assesses the position and health of the placenta, the amount of amniotic fluid surrounding the fetus, and the umbilical cord’s connection.
Potential Findings
While many scans offer reassuring news, the 20-week anatomy scan can sometimes identify potential concerns. These findings include structural anomalies, growth concerns, or issues related to the placenta or amniotic fluid. Structural anomalies involve the physical development of organs or body parts. For instance, heart defects, kidney abnormalities, or a cleft lip can be detected.
Skeletal abnormalities, such as limb development issues or spinal defects like spina bifida, can also be identified. Some findings might relate to fetal growth, indicating abnormal growth. Placental issues, such as a low-lying placenta (placenta previa), or abnormal amniotic fluid volume can also be observed. Many of these findings are minor or manageable, and some may require further investigation to confirm their significance.
How Common Are Concerns
The vast majority of 20-week anatomy scans reveal no significant concerns, with most babies appearing to develop typically. Approximately 85% to 90% of these scans show a normally developing fetus. However, a smaller percentage, 10% to 15%, may identify a finding that warrants further investigation or follow-up.
These findings range widely in their implications, from minor variations that may resolve on their own to significant conditions requiring specialized care. Not all findings represent a severe problem; some are “soft markers” that might indicate a slightly increased risk but often prove benign. False positives can also occur, where an initial finding is not confirmed after further diagnostic testing. Many findings are ultimately deemed insignificant.
What Happens After a Finding
If a concern is identified during the 20-week scan, the healthcare team will recommend next steps. This often begins with a follow-up ultrasound, sometimes a more specialized one performed by a maternal-fetal medicine specialist, to confirm the initial observation. Additional diagnostic tests might be suggested, such as amniocentesis or chorionic villus sampling (CVS), to check for chromosomal or genetic conditions.
Consultations with various specialists are common, depending on the nature of the finding. For example, a pediatric cardiologist might be involved for heart concerns, or a pediatric surgeon for structural anomalies requiring intervention after birth. The healthcare team will provide comprehensive information, explain all available options, and offer support throughout this period. Understanding the implications and exploring care options are central to navigating this situation.
References
1. url: “https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8949547/”
content: “The 20-week anomaly scan is a routine ultrasound examination performed between 18 and 22 weeks of gestation. It is used to assess fetal anatomy, growth, and well-being. The majority of scans (85–90%) are normal, but 10–15% may show a finding that requires further investigation. The types of abnormalities detected range from minor to severe, and some may resolve spontaneously. False positives can occur, and further diagnostic tests may be needed to confirm a diagnosis.”
title: “The 20-Week Anomaly Scan: A Comprehensive Review”
2. url: “https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7604172/”
content: “The 20-week anomaly scan is a routine ultrasound examination performed between 18 and 22 weeks of gestation. It is used to assess fetal anatomy, growth, and well-being. The majority of scans (85–90%) are normal, but 10–15% may show a finding that requires further investigation. The types of abnormalities detected range from minor to severe, and some may resolve spontaneously. False positives can occur, and further diagnostic tests may be needed to confirm a diagnosis.”
title: “Fetal Anomaly Scan: An Overview”