By Ultrasound Specialist, Fatima Ghani
What is an ultrasound?
An ultrasound is a device that uses high frequency sound waves to create an image of some part of the inside of the body. The purpose of using ultrasound in pregnancy is to monitor your baby’s health and reassure you. It also enhances bonding between you and your unborn child, as ultrasound scans are one of the highlights of the pregnancy journey.
When will the scans be done?
1’st trimester (5 – 10 weeks)
A gestational sac can be seen by six weeks. Your pregnancy can be confirmed, and the foetal pole (thickening on the margin of the yolk sac of the foetus) will be measured.
Your baby’s heartbeat will be documented, multiple pregnancies can be seen, and a due date estimated.
Measurement of the cervix and ovarian cysts can also be documented at this time.
1’st trimester (11 – 14 weeks)
To check for foetal chromosomal defects, e.g. Down’s syndrome, trisomy 13 and trisomy 18, a detailed ultrasound will examine the fluid collection at the back of your baby’s neck.
The nasal bone, foetal organs and heart rate are also checked.
A maternal blood test, the ultrasound findings, and your age, will determine if you need an amniocentesis (drawing of amniotic fluid to screen for abnormalities).
2nd trimester (18 – 24 weeks)
Your baby’s head, abdomen and femur bone will be measured to determine his size and weight. Detailed screening examines his structural development, growth parameters and markers for chromosomal abnormalities.
The placental position, foetal weight, amniotic fluid volume, and foetal movements will also be documented.
3rd trimester (24 – 40 weeks)
Scans during this period will determine the growth of your baby and any malformations that may manifest in the later stages of your pregnancy. His position in the placenta, his weight and his movements are important at this stage, as is the amniotic fluid volume.
How accurate is ultrasound scanning?
The accuracy of an ultrasound is largely dependent on the operator. An experienced, skilled operator is likely to produce more accurate results.
Abnormalities detected by ultrasound:
- Spina bifida
- Ectopia cordis
- Sacral teratoma
- Skeletal dysplasia
- Cleft lip/palate
- Club foot
- Siamese twins.
Keep in mind that not all abnormalities can be diagnosed on ultrasound, and a normal scan is not a guarantee that everything is normal.
3D/4D Scans are an impressive sneak preview of your baby. Movements such as swallowing, sucking, waving, blinking and yawning can be easily observed. The best images are obtained when there’s sufficient fluid around him, and nothing obscures the field of interest.
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