Routine scan
Detailed Scan
婦健 Femina Healthcare 4D Ultrasound, Prenatal Diagnosis & Treatment Centre   8   704-707    (   A2 )  Suite 704-707, Grand Centre, 8, Humphrey Avenue, Tsim Sha Tsui (TST MTR A2 Exit) 23682333
 18-20 Week Morphology Scan  Why is the scan done?This is a routine examination performed in nearly all pregnancies.  As most patients will have had a 12 week nuchal translucency scan which has already determined the:


• Number of babies present
• Due date
• Risk of Down’s syndrome and other chromosome abnormalities

 This 18 – 20 week scan is more to assess:
• Fetal structural (morphological / organ) development
• Early fetal growth
• Placental position
• Amniotic fluid volume
  

What else is the scan called?There are a number of synonyms used for the 18-20 week scan including “genetic scan” “anomaly scan” and “morphology scan”.   

What part of the baby will be seen?You will notice a dramatic difference in the anatomic detail visible in your baby on this scan when compared to the 12 week scan. The ultrasound will endeavour to evaluate the fetal brain, face, spine, heart, lungs, stomach, kidneys, bladder, cord insertion at the belly button, arms and legs, placenta cervix and amniotic fluid.  

Can all abnormalities be seen? An amazing amount of detail can often be seen. However it is important to realize that not all parts of the baby show up well with ultrasound. No ultrasound examination can ever guarantee a normal fetus. The best centres in the world consistently report on the limitations of ultrasound and its inability to detect all fetal abnormalities.  Up to half the fetal heart defects will not be seen. Some of these are only minor, but some may not be apparent until the fetus is bigger, later in the pregnancy. Many bone growth problems, forms of dwarfism, will only be possible to be suspected late in pregnancy and the diagnosis is made on x-rays taken after the baby is born. If you have a normal detailed scan result, up to 98% of babies born will be structurally normal.    

What about diagnosing Down syndrome?Down syndrome is a problem whereby every cell in the body has an extra chromosome 21. There is no specific diagnostic finding on ultrasound. It is necessary to look at fetal cells down a microscope to diagnose a chromosomal abnormality. Hence, chromosomal lesions such as Down syndrome, cannot be diagnosed with ultrasound. Some 40% of Down syndrome fetuses will appear normal on the 18-20 week scan. Sometimes, there may be some ultrasound findings which can make us suspicious of an increase chance that the fetus has a chromosome lesion. However, noninvasive ultrasound screening for chromosome lesions is best done at the 12 week nuchal translucency scan.  

Are there any serious abnormalities never seen?Conditions such as cerebral palsy, blindness, deafness, autism and most skin and soft tissue lesions are never detected with ultrasound. The fetal position and size of the maternal abdomen are important factors that affect fetal anomaly detection. It is better if your bladder is not emptied just before the scan as it helps push the uterus above your pubic bone and generally makes the scanning more technically satisfactory. We don’t require your bladder to be uncomfortable. Water, tea and coffee is available in our waiting room.  

Can I tell the sex of my baby? Fetal sex can often be determined on this scan. Ultrasound is never 100% accurate and fetal position and cooperation will play a big part. If you don’t wish to know the sex please tell us at the start of the examination so we can tell you when to look away from the screen.

Can I bring my partner or support person?

You are most welcomed to bring your family and support person. We do ask that if young children are to come with you an adult should also attend to help look after them. Although it usually isn’t a problem sometimes young children can be distracting to the examiner.

Is ultrasound safe? Ultrasound has been used throughout the developed countries all over the world for the past 30- 40 years and no significant harmful effects of obstetric ultrasound have been shown. It is considered safe.