Baby Scanning (Pregnancy Ultrasound Examinations)
Ultrasound has become a routine part of the care of pregnant women enabling obstetricians and pregnant women insight into the development and appearance of the unborn baby. From screening for Down Syndrome and examining the baby for normal development, through to sexing the baby, estimating the baby's size and providing 3D and 4D images, modern ultrasound equipment and technical expertise enables women to avail themselves of a full pregnancy ultrasound service.
'Fetal Imaging' is the ultrasound service provider working in conjunction with Nuffield Health Glasgow Hospital to deliver leading edge antenatal imaging services. These services are led by two consultant obstetricians and specialists in Foetal Medicine, Professor Alan Cameron and Dr. Philip Owen, both of whom have many years of experience in pregnancy scanning. We use a state of the art ultrasound machine at the Nuffield Health Glasgow Hospital. The obstetricians will be happy to answer any queries that you have regarding the examinations or any other aspects of your pregnancy management.
It is not necessary to be referred for an ultrasound scan with most women booking their scan directly. Each scan is accompanied by digital images of the scan (on CD or DVD as appropriate) and a written report provided.
Early pregnancy scans
These scans are performed for several reasons. The principal reason is for reassurance that the pregnancy is progressing satisfactorily and that the baby's heartbeat is present. The age of the pregnancy is easily determined through ultrasound measurement and the presence of one, two or more babies is established.
The examination is usually carried out by scanning through the abdomen but if the pregnancy is very early, scanning via a probe inserted into the vagina may be appropriate (transvaginal ultrasound).This scan is of value to any woman who may have concerns about her pregnancy, who is unsure of how far along she is or simply wishes to see the pregnancy progressing.
Nuchal scan - The combined ultrasound and biochemistry scan (CUBS)
This assessment is for women who wish to have a screening test for the prediction of a baby with Down's Syndrome. The test combines the woman's age, the measurement of 2 proteins (biochemical markers) in the mother's blood and a measurement of the skinfold behind the baby's neck at 11 and a half to 14 weeks' of pregnancy. A new development in first trimester screening is the assessment of the nasal bone. If you are expecting twins then the Down's risk is calculated from the nuchal ultrasound measurement and the mother's age alone.
What is the CUBS test?
The CUBS (combined ultrasound and biochemistry scan) test is based on the screening test developed by the Fetal Medicine Foundation in London and subsequently pioneered for Scottish women by the consultants who work in the Nuffield. The consultants have been trained by the Fetal Medicine Foundation and the biochemical markers are assayed by the Regional Genetics Laboratory in Glasgow.
The test is best performed between 11 and a half and 14 weeks. The scan is similar to the first 'booking' or early pregnancy scan but may take 20-30 minutes because of the additional detail required to make the measurements. The scan is usually best performed with an empty bladder as the consultant may need to press firmly on the abdomen to get the best views of the baby's neck.
The fetal nasal bone can be visualized by sonography at 11-13+6 weeks of gestation. Several studies have demonstrated a high association between absent nasal bone at 11–13+6 weeks and trisomy 21, as well as other chromosomal abnormalities. In the combined data from these studies on a total of 15,822 foetuses the fetal profile was successfully examined in 97.4% cases and the nasal bone was absent in 1.4% of the chromosomally normal foetuses and in 69% of foetuses with trisomy 21.
The results of the first 6000 screening CUBS tests have revealed that the test has a greater than 90% detection rate for Down's syndrome which is appreciably better (more accurate) than the routinely available blood test offered at 15 to 20 weeks. CUBS testing is the current 'gold standard' screening test for Down syndrome; the HeaIth Technology Assessment, an evaluation carried out by the Health Department of the Scottish Executive published in 2004 (www.nhshealthquality.org) has recommended that CUBS testing be made available to all women having babies in Scotland. It is not yet widely available in Scottish maternity hospitals. The addition of nasal bone assessment to the CUBS test is estimated to improve the detection rate for Downs syndrome to 95%.
The blood sample will be taken by one of the clinic staff and women will be informed of their results by telephone after 2-4 days. A written report is posted to your address.
The result of the screening test is reported in two ways. Firstly, the result is categorised into a 'low risk' or a 'high risk' result. The cut-off for determining the two risk categories is 1 in 250. Ninety-five percent of women will have a 'low risk' result and no further action is usually recommended. The actual risk of Down's syndrome is also provided; the lowest risk that can be quoted is less than 1 in 20,000 whilst the highest is greater than 1 in 2.
Should a high risk of Down's syndrome be received, your consultant will discuss the implication of the result with you.
The integrated test
There is high-quality evidence to indicate that combining results of first- and second-trimester screening tests improves the diagnostic performance for Down’s syndrome and other chromosomal anomalies and is better than when either of them is used alone.
The integrated test seems to have a higher detection rate and a lower FPR compared with other currently used combined screening tests. The performance of all screening tests is well reviewed in the recently published NICE guideline on Antenatal care (www.NICE.org)
The test is a 2 stage procedure incorporating the Nuchal scan as outlined above followed by the blood test performed at 15 weeks. The results are available after 15 weeks.
Detailed scan (also called 'fetal anomaly' or '20 week' scan)
The majority of babies develop normally in the womb but a small percentage are affected by either minor or major problems. Knowledge of such developmental problems can be invaluable in planning the appropriate care for the pregnancy. Equally, the absence of any abnormalities or problems on the scan can be a source of much re-assurance to the expectant parents.
This ultrasound examination serves to perform a full assessment of the baby's development in order to reassure the parents that the organs have formed normally. This includes an examination of the major organs such as the brain, face, spine, heart, stomach, kidneys, bladder, upper and lower limbs and genitalia (sexing) if requested.The examination is best conducted at between 20 and 24 weeks but can be performed at any stage of pregnancy beyond 18 weeks.
It is recommended by the HeaIth Technology Assessment, an evaluation carried out by the Health Department of the Scottish Executive published in 2004 (www.nhshealthquality.org) that all women be offered a detailed scan. Detailed scans are currently routinely available in some but not all Scottish maternity units.
It is important to understand that it is not possible to diagnose all abnormalities using ultrasound. This is particularly the case for heart and brain abnormalities where only 60% of all abnormalities are detected using ultrasound. Factors which influence the quality of the image obtained are the age of the pregnancy (better at 22 weeks than 18), the position of the baby and the patient's bodyweight (image quality tends to be poorer if the woman is heavy) . If the views are not adequate, this will be explained by the consultant and arrangements made for a repeat examination.
In the unusual situation where an abnormality is found or suspected, the significance of this will be explained and a plan of management discussed.
Still and moving images from the detailed scan are recorded to CD/DVD.
In addition to performing a detailed scan it is also possible to use the new 3/4D technology to obtain further images of your baby. The best quality 3/4D images are obtained between 24 and 30 weeks gestation.
3D and 4D ultrasound scans
Using new ultrasound technology it is possible to obtain lifelike images of the unborn baby in 3 and 4 dimensions (4D is moving 3D). Such images are very popular with parents since they provide easily recognisable images of their baby’s face in particular which they can share with family and friends. Smiling, yawning and sucking is often seen depending on how awake or asleep the baby is.
The quality (how clear they are) of the 3/4D images is mostly determined by the baby’s position and how far along the pregnancy is. The best time to do a 3/4D scan is between 26 and 32weeks. It is difficult to influence the baby’s position but time is set aside to allow the baby to wake and move around if necessary. If it is not possible to obtain satisfactory images (which is very unusual) for whatever reason then we will make arrangements for a further scan or adjust the charge depending on your preference.
At the Nuffield we offer 3/4D imaging as an additional component to either a detailed scan or a fetal growth and wellbeing scan. A report from the scan is produced as usual. It is also possible to book a sonographer performed 3/4D studio scan with or without identification of baby’s gender.
The images are stored on to a CD or DVD so providing a lasting record.
Growth and wellbeing scan
When is this done?
This examination is normally performed later in pregnancy (> 26 weeks) when a woman wishes to have the baby's size estimated. This scan concentrates on performing measurements of the head, waist, and thigh bone. It is possible to estimate the baby's weight using these measurements.
The baby's wellbeing is assessed by examining the amount of fluid around the baby and the function of he placenta ('afterbirth') using a technique called Doppler ultrasound. Doppler measures the pattern blood flow in the baby's umbilical cord. The new 3/4 D technology can also be achieved at the growth and well being scans demonstrating baby's facial features and often baby yawning, sucking, grimacing and sometimes smiling.
Please note: not all hospitals perform every type of scan. Please call our contact centre on 08456 034346 to confirm what scans are available in your area.