Pregnancy Ultrasound Scans

The Oaks Clinic offers comprehensive services for pregnant women in its modern clinic in Loughton, Essex. The clinic is accredited for Downs Syndrome screening. 3D / 4D scans are offered as part of a fetal well-being scan.

Scans undertaken during the course of pregnancy can be broken down into those done in early pregnancy (from 6 – 14 weeks gestation), mid-pregnancy (from 14 – 26 weeks gestation) and late pregnancy (from 26 - 40 weeks gestation). The following ultrasound scans are routinely offered by The Oaks Clinic:

Early viability scan
This scan is performed between 6 to 10 weeks gestation and may be performed by placing the scanning probe on the abdomen, or by gently inserting a hygienically covered internal scanning probe into the vagina in instances where the views are obscured by the abdominal route. The viability scan is important as it establishes the presence of a healthy ongoing pregnancy and excludes a miscarriage, which can affect as many as 1:20 pregnancies at this gestation. It also helps to exclude a tubal or ectopic pregnancy and gives the first indication of the number of developing babies within the uterus.

This scan usually takes between 10-15 minutes. An abdominal scan at this gestation requires a full bladder. In the event that the scan needs to be performed vaginally, it will be necessary to empty the bladder in preparation.

11-13 week scan
This scan is undertaken when the measurement from the crown to the rump of the developing baby is between 48-84mm. That is usually between 11 weeks +3 days and 13 weeks +6 days. It is sometimes referred to as the 11-13 week scan and it allows for detailed assessment of the developing baby and has a number of benefits:

- Dating and confirmation of viability - In most women this is the first routine scan that confirms that there is a developing baby within the uterus. The chance of miscarriage at this stage is about 2%. This scan also confirms the date of delivery of the baby to within 5 days, so accurately dates the pregnancy.
- Early anatomy assessment - At this stage limb development has begun, we are able to record a normal heartbeat and, depending on the gestation, the beginnings of the development of a normal brain, skull, heart and lungs can be seen. A developing spine, kidneys and bladder can all be seen, and will be shown to you at the time of the scan. It is at this scan major abnormalities can sometimes be identified. We will also spend time looking at the placenta, where it lies within the uterus and where the cord is inserted, as this may have implications for the pregnancy later on.
- Risk assessment for chromosomal defects - The 11-13 week scan is an important part of the risk assessment for chromosomal defects, such as Down’s Syndrome. The other component of this screen is the assessment of two pregnancy hormones, which are obtained from a blood sample taken on the day of the scan or a day or two previously. If the blood sample is taken the day of the scan the results should be available within 48 hours; if the blood sample is taken a day or two before, the result can be given on the day of the scan. The vast majority of results are low risk; however in the event of a high risk result, or if you want complete reassurance that your baby is not affected by Down’s Syndrome, then we are able to offer an invasive test, which can be a CVS (chorionic villus sampling) where a small sample of placenta is taken under local anaesthetic or an amniocentesis test (usually after 16 weeks gestation) where a sample of amniotic fluid is taken from around the baby. The invasive test is done after discussion about the associated risks.
- Identification and determination of multiple pregnancy - There are two types of twin pregnancy. One where the babies have separate placentas and sacs; these are by far the most common type of twin pregnancy and, although some of these babies may still be identical, the majority are referred to as non-identical, or dichorionic twin pregnancies. Both babies may or may not be of the same sex. Twin pregnancies where the placenta is shared are referred to as monochorionic twin pregnancies. These pregnancies are by far the highest risk pregnancies and can be differentiated from the dichorionic twin pregnancy at this scan.

This scan takes 20-30 minutes and a full bladder is required for this scan.

Reassurance scan
There is no routine scan between the 11-13 week scan and the anomaly scan. However, some women need confirmation of continuing viability. This scan is undertaken between 14 weeks and the time of the anomaly scan. Careful assessment of the fetal anatomy is performed at this time but this does not replace the routine anomaly scan.

This scan takes 15-20 minutes and there is usually no need for a full bladder for this scan.

Gender assessment (sexing) scan
The earliest the sex of the developing baby can be assessed is from 15 weeks. Usually the obstetrician or sonographer will be able to tell you what sex the baby is at this scan; however this will be affected by the position and the mother’s weight, so it may need to be repeated at a later date. Basic measurements of the fetal head, abdomen and limbs will be taken at this scan. If possible a picture of the baby will be given.

This scan takes about 10-15 minutes. You usually do not need a full bladder.

Anomaly scan
This scan may be referred to as the 20 week scan but it is offered between 18 and 20 weeks and 6 days of your pregnancy. It allows the sonographer / obstetrician to assess the growth and development of the baby by measuring the size of the head, abdomen and limbs. The scan allows us to assess the amount of fluid around the baby, where the placenta lies and a repeat assessment of the type of cord insertion and number of vessels in the cord. The main aim of this scan is to exclude the possibility of a fetal abnormality. A detailed assessment of the baby is undertaken beginning at the head, brain and spine, the face, chest and abdomen including the heart, stomach, lungs, kidneys and upper and lower limbs. Assessment of gender can be undertaken during this scan at the parents’ request. Occasionally, due to fetal positioning or in mothers who have had previous surgery or are overweight, the scan may need to be repeated to complete the assessment. Although this scan provides reassurance that the baby is developing normally, not all fetal abnormalities can be excluded by ultrasound alone.

Usually this can be undertaken at one visit, and takes about 30-40 minutes. A full bladder is needed for this scan.

Uterine artery Doppler scan
Performed between 21 - 24 weeks gestation, this scan may be done abdominally or vaginally using the internal scan probe, when it can be performed at the time of assessing the cervix length. It allows the obstetrician or sonographer to determine the chances of an untoward outcome in the current pregnancy by recording the blood flow in the arteries supplying the uterus and placenta. It is used specifically for women who have had pregnancies complicated by high blood pressure (pre-eclampsia), premature separation of the placenta (called abruptio placenta) and growth problems of the baby in a previous pregnancy. It is also recommended in women who have significant medical problems preceding the pregnancy, such as high blood pressure (hypertension), kidney disease or diabetes.

This scan takes 5-10 minutes abdominally; however, if it performed during the cervical assessment scan it may take up to 15 minutes. There is usually no need for a full bladder for this scan.

Cervical assessment scan
The length of the cervix can be a predictor for preterm, or premature, birth. In women with a history of surgery to the cervix, preterm delivery or late miscarriages in previous pregnancies, assessment of the cervix may be needed to reassure that this is unlikely to happen again. It may alert the obstetrician to the fact that a shortening cervix may benefit from a cervical suture. The best way to assess the length of the cervix is by using an internal ultrasound probe. As with the early viability scan it is performed with an empty bladder. A hygienically covered ultrasound probe is inserted into the vagina until the cervix can be seen and measured. In patients with the previous history described above, the scans are usually sequential beginning at 16 weeks gestation and then 2 weekly until 24 weeks gestation, aiming to identify the time when significant shortening of the cervix occurs.

This scan usually takes between 10-15 minutes, and a recently emptied bladder is required for this scan.

Fetal well-being scan
This scan, undertaken between 23 - 40 weeks, is not routinely offered by the NHS but mothers often feel reassured at having another fetal assessment after their anomaly scan. This scan can be undertaken any time after the anomaly scan but if it is done in conjunction with a 3D / 4D bonding scan it is recommended that it is done between the 26th and 34th week of the pregnancy, when the views are optimal. See 3D / 4D scan.

This scan usually takes between 15-25 minutes, and a full bladder is required for this scan.

Growth scan
The growth scan is offered, usually between 28 - 38 weeks gestation, if there is a history of small babies in a previous pregnancy, or if there appears to be concern about fetal well-being during the pregnancy. The baby’s weight is assessed, looking at the size of the fetal head, size of the baby’s abdomen and length of its femur. The growth scan can be performed as a series to assess whether or not the growth continues along the right course and allows us to note when the growth is tailing off. An umbilical artery Doppler scan is undertaken at the same time to assess the blood flow between the developing baby and the placenta if there is concern about fetal well-being.

The frequency of the growth scans will depend on the amount of concern for the fetus but is usually not more that every 2 weeks.

This scan usually takes between 15-25 minutes, and a full bladder is required for this scan.

3D / 4D scan (bonding scan)
This scan allows the parents to see their baby in as near normal appearance as possible prior to delivery, because it gives a three dimensional image of the baby. A 4D scan is a 3D scan with the added dimension of time, as in a film or video in which the baby can be seen moving inside the uterus. This scan is not usually performed for medical reasons, unless the baby has a facial or limb abnormality where the 3D image can help the parents to understand the problems identified.

During a 3D scan, we will always perform a fetal well-being scan first. A good 3D image of the baby depends on its position and the amount of amniotic fluid around the baby so it may take some time to get a good view of the baby. Occasionally, you may be asked to change position or go for a walk and return later in an attempt to get the baby in a better position for the scan.

The best time to do a 3D scan is between 26 and 32 weeks as at this time there is more amniotic fluid surrounding the baby, it is not too large in the uterus and the facial features are more defined.

The cost of the 3D / 4D scan includes a scan report and 3D scan pictures, along with a DVD of moving images.

This scan takes about 30 minutes and a full bladder is required for this scan.