Also known as a 19 – 20 week anatomy or anomaly scan, the morphology ultrasound is considered to be part of the routine obstetric care that all patients should receive.
The purpose of this scan is to assess:
- Age of pregnancy / size of fetus.
- Number of babies in the uterus.
- Baby’s physical development and anatomy. This involves detailed examination of the baby’s head, brain, face, lips, heart, stomach, lungs, abdominal wall, kidneys, bladder, spine, arms, legs, hands and feet.
- Position of the placenta.
- Volume of fluid around the baby.
This scan is ideally performed at 19 – 20 weeks which enables visualisation of the structures more easily and clearly.
It is important to appreciate ultrasound does not detect all abnormalities. Many congenital heart abnormalities are complex and not visualized at the morphology examination. In many instances the view of the fetus may be hampered by the fetal position or movement at the time of examination. Maternal obesity may impair adequate visualization of the baby and in some instances the patient may be rebooked for further assessment of the fetus.
In other certain circumstances fetal abnormalities may not be evident on ultrasound despite adequate views. This may be explained by the natural history of the condition where the abnormality only becomes evident later in pregnancy or where there are in fact no structural changes in the baby (eg. cerebral palsy, biochemical abnormalities and some chromosomal abnormalities).
In most cases the ultrasound will be performed transabdominally but there are some situations where an internal or transvaginal ultrasound may be necessary. Transvaginal ultrasound involves placing a thin transducer (slightly thicker than a tampon) into the vagina. The transvaginal ultrasound can offer extra detail to the examination as it allows the ultrasound probe to come into close proximity to the uterus. Measurements of the cervix completed at the time of a morphology scan are also generally performed transvaginally. A transvaginal scan is optional for all patients and it is your decision whether to proceed with that part of the examination.
Transabdominal and transvaginal ultrasound examinations are safe investigations at all stages of pregnancy.
About this Ultrasound
Your examination will be performed by a sonographer. Upon being taken into the examination room the sonographer will introduce themselves, confirm your identity and examination. A clear gel is applied to the skin over the area to be examined (lower abdomen/pelvis). The ultrasound probe is then placed in contact with the skin and moved over the surface to study the structures below. Occasionally the fetus may not be in a good position so you may be asked to lie on your side or go for a short walk to help it move. In rare occasions you may be required to have a transvaginal ultrasound to better see these structures or return later in the day or the following day to scan when the baby has moved into a better position.
We ask that you limit the number of people attending the exam; ideally yourself and a support partner. If you have young children it is often a good idea to arrange child care for them or have someone come along that can care for them in the waiting room while you have your examination. When the scan is complete the sonographer will be happy to allow some others into the room briefly to view the baby. It is Dr Jones and Partners policy that you refrain from taking any video of the ultrasound examination and that all electronic devices are turned off. You will be able to obtain some images at the end of your examination in accordance with the Dr Jones and Partners multimedia policy.
If you wish to know the gender of your baby please ask the sonographer during the scan. The morphology ultrasound is often the first time fetal gender can be seen, but you should be aware that assessment of the sex is not 100% accurate. There also may be some occasions where the genitalia may not be visible due to fetal lie or position. If you do not wish to know the sex of the baby, please inform the sonographer at the beginning of the exam.
If you require a transvaginal ultrasound to measure your cervix or obtain better detail of your baby, you will be asked to empty your bladder and change in to a gown. The transvaginal transducer is disinfected and a protective cover is placed over the transducer each time it is used, so there is no risk of infection. The probe is then lubricated with gel prior to insertion into the vagina, and then moved gently to visualise the structures required. This part of the examination generally takes 10-15 minutes. If at any time the examination is causing excessive discomfort or you wish the examination to end, please advise the sonographer immediately.
Before your Scan
Ideally book your appointment when you will be 19 – 20 weeks.
It is a good idea to wear comfortable, loose fitting clothing that allows easy access to the area that is being imaged, so two piece clothing is ideal (separate upper/lower garments).
Transabdominal: A full bladder is required. Drink 500mL of water finishing one hour prior to your appointment and do not empty your bladder. Distension of your bladder provides a window to view your pelvic organs through and compresses bowel out of the way. Your bladder need not be overly full that it causes you pain or distress; please advise reception staff on arrival if this is the case and you will be advised of your options. If during the examination your bladder is causing you discomfort, please advise the sonographer.
Transvaginal: If this imaging is required it is performed with an empty bladder.
Preparation details for your examination will be confirmed when you make your appointment.
Approximately 60 minutes.