Obstetric Ultrasound
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A pregnancy ultrasound scan is a key part of prenatal care and is used to assess fetal development and health.
There are different types of ultrasound scan to be done throughout your pregnancy journey, and they will provide you with the insights you and your fetus need.
Why is an ultrasound scan for pregnancy important?
Here are some key reasons why ultrasound scans are essential in pregnancy:
1
Monitoring fetal development
Ultrasound scans allow doctors to monitor the fetus’s growth, ensuring it is developing as expected.
2
Detecting potential complications
Scans can help detect any possible complications such as ectopic pregnancy, multiple pregnancies, or fetal abnormalities early on, enabling prompt treatment and management.
3
Assessing placental healt
Assessing the health and position of the placenta ensures optimal fetal nourishment and minimises the risk of complications such as placenta previa.
4
Guiding prenatal interventions
In some cases, ultrasound scans may guide prenatal interventions such as amniocentesis or chorionic villus sampling (CVS) for genetic testing.
What are the types of ultrasound scans needed during pregnancy?
Several types of ultrasound scans may be recommended throughout pregnancy based on the stage of gestation and specific clinical indications. Here’s an overview of the different types of ultrasound scans.
The nuchal translucency (NT) ultrasound scan is typically done around the 11th to 14th week of pregnancy. It measures the thickness of the fluid-filled space at the back of the baby's neck, for risk of chromosomal abnormalities.
First-trimester screening combines a first-trimester ultrasound and blood tests to assess the baby's health during early pregnancy more accurately. It assesses the risk of chromosomal abnormalities and other genetic conditions, offering a clearer picture of the baby's well-being within 13 weeks of pregnancy.
Genetic ultrasound scans, also known as anatomy or anomaly scans, are usually conducted between 18 and 22 weeks of pregnancy. They provide a detailed assessment of the baby's anatomy, looking for structural abnormalities or developmental issues.
Similar to genetic ultrasound scans, fetal anomaly scans evaluate the baby's anatomy for abnormalities that may require further investigation or management.
Unlike traditional 2D ultrasound scans, 4D ultrasound provides real-time, three-dimensional images of the baby in utero, offering expectant parents a lifelike view of their unborn child.
NIPT involves analysing cell-free fetal DNA circulating in the mother's blood to screen for chromosomal abnormalities such as trisomy 21 (Down syndrome), trisomy 18 (Edwards syndrome), and trisomy 13 (Patau syndrome).
In cases where additional diagnostic information is needed, prenatal invasive procedures such as amniocentesis or chorionic villus sampling (CVS) may be performed under ultrasound guidance.
Ultrasound scans are also used to assess various aspects of the pregnancy itself, including the position of the fetus, the amount of amniotic fluid, and the health of the cervix.
First Trimester NT Ultrasound Scan
First Trimester Screening
Genetic Ultrasound Scan
Fetal Anomaly Scan
4D Ultrasound
Non-invasive Prenatal Testing
Prenatal Invasive Procedures
Assessment of pregnancy
When is the best time to have a pregnancy ultrasound?
It is best to have your first pregnancy ultrasound between eight and twelve weeks to confirm it and estimate a due date. Succeeding ultrasound scans will be performed regularly and according to the gestation of the pregnancy. Here are some general guidelines:
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First trimester
NT ultrasound scan and first-trimester screening are typically performed between 11 and 14 weeks of pregnancy.
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Second trimester
Genetic ultrasound or anatomy scan is usually conducted between 18 and 22 weeks of pregnancy.
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Third trimester
Additional ultrasound scans may be recommended to assess fetal growth, amniotic fluid levels, and placental function.
Your doctor will determine the most appropriate timing for ultrasound scans based on your circumstances and any pregnancy-related concerns.
What should you expect during an obstetric ultrasound?
An ultrasound scan is a non-invasive and painless procedure. Usually, no special preparation is required for a routine ultrasound scan. However, you may be asked to drink water and have a full bladder for certain scans.
During the ultrasound scan, you will lie on a comfortable examination table, and a warm gel will be applied to your abdomen to facilitate the transmission of sound waves. The ultrasound transducer will then be gently moved over your belly to capture images of the fetus. The whole procedure should last between 20 to 30 minutes.
Can a pregnancy ultrasound detect congenital disabilities?
Yes, ultrasound scans can detect certain congenital disabilities and developmental abnormalities. However, not all congenital disabilities may be visible on ultrasound, and some may only become apparent later in pregnancy or after birth.
Furthermore, certain genetic conditions may not be detectable through ultrasound alone, so additional testing, such as NIPT or invasive procedures, may be recommended in some cases.
Ultrasound scan for pregnancy in Singapore
Pregnancy ultrasound provides valuable fetal development information, detects potential complications, and reassures expectant parents.
At our clinic, we understand the importance of obstetric ultrasound in ensuring the health and well-being of both mother and baby. Our experienced doctors are committed to providing comprehensive prenatal care, including ultrasound imaging services.
Dr TC Chang has been in medical practice since 1986. He is the Head of Maternal Fetal Medicine, Fetal Assessment Unit, Thomson Medical Centre .He practices at SWC Gynae Associates, Thomson Medical Centre as a Consultant Obstetrician and Gynaecologist.
Frequently Asked Questions
Most doctors perform the first pregnancy ultrasound at no earlier than seven to eight weeks. However, a gestational sac is usually visible at five weeks after your last period, and a fetal heartbeat detected at five to six weeks. Monitoring for a fetal heartbeat at this stage can provide early reassurance for expecting parents.
Most expectant parents have one or two ultrasounds during pregnancy, but the number may increase as recommended by the doctor or for high-risk pregnancies and health conditions.
Transabdominal ultrasounds are done over the abdomen, while transvaginal ultrasounds involve inserting a transducer into the vagina for closer images of early pregnancy. Therefore, the main difference lies in the imaging method used.
Your doctor will discuss the ultrasound findings with you and provide detailed information about the nature of the abnormalities, their potential implications for the pregnancy, and any recommended follow-up steps.
Depending on the nature of the abnormalities, they may recommend additional diagnostic tests to gather more information and confirm the diagnosis.