Obstetrics

Fetal Viability and Dating scan (6-11 weeks).

This is an ultrasound examination that is usually carried out abdominally but may require trans-vaginal examination in very early pregnancy. It aims to determine the number of foetuses present and whether the pregnancy is progressing normally inside the uterus. This scan is useful for women who are experiencing pain or bleeding in the pregnancy and those who have had previous miscarriages or ectopic pregnancies. Black and white 2D images, DVD & report supplied

Nuchal Scan (11+3weeks - 13+6weeks)

The vast majority of babies are normal. However all women, whatever their age, have a small risk of delivering a baby with a physical and/or mental handicap. In some cases the handicap is due to chromosomal abnormality such as Downs Syndrome. The only way to know for sure whether or not the fetus has a chromosomal abnormality is by having an invasive test such as chorion villus sampling (CVS) or amniocentesis (amnio). However these tests carry a risk of miscarriage of about 1%. It is up to you and your partner to decide whether or not the risk of the fetus having a chromosomal abnormality is high enough to warrant having an invasive test. As a guideline, an invasive test is usually offered if the risk of Downs Syndrome is 1 in 300 or above. The most accurate way of estimating the risk of the fetus having Downs Syndrome is carried out at 11+3-13+6 weeks and depends on the:

  • Age of the mother
  • Amount of fluid behind the neck of the fetus (nuchal translucency)
  • Presence or absence of the fetal nasal bone
  • Presence or absence of any physical abnormalities

Only you can then decide if you wish to have an invasive diagnostic test.

Irrespective of whether or not you decide to have an invasive test, it is recommended that you have a scan at 20 weeks to check for physical abnormalities. This scan can almost always be carried out transabdominally. There are a number of benefits:

1. To date the pregnancy accurately. This is particularly relevant for women who cannot recall the date of their last period, have an irregular cycle, or who have conceived whilst breastfeeding or soon after stopping the pill. We measure the size of the fetus and from this we calculate the expected date of delivery.

2. To assess the risks of Downs Syndrome and other chromosomal abnormalities. Each woman will be given an estimate of her individual risk for this pregnancy. This is calculated by taking into account the age of the mother, amount of fluid at the back of the neck (NT), nasal bone if possible and fetal abnormalities. Parents will receive full counselling concerning the significance of these risks and the various options for further testing.

3. To diagnose multiple pregnancy. Approximately 2% of natural conceptions and 10% of assisted conceptions result in multiple pregnancy. Ultrasound scanning can determine if both babies are developing normally and if the babies share the same placenta which can lead to problems in the pregnancy. In such cases it would be advisable to monitor the pregnancy more closely.

4. To diagnose certain major fetal abnormalities. Major abnormalities may be visible at this gestation but a 20 week anomaly scan is essential.

The National Institute for Health and Clinical Excellence (NICE) recommends the combined test for Downs Syndrome Screening using the Nuchal Translucency Ultrasound scan and a blood test.

The blood test can be arranged on the same day as the scan and the combined risk for Downs syndrome will be available in approximately two weeks time. Alternatively the bloods can be taken and sent to the laboratory in Leeds ten days prior to the ultrasound scan. In this case the combined risk for Downs syndrome will be available on the same day as the ultrasound scan. Please contact the office to find the most appropriate option for you and your family.

Black and white 2D images, DVD & report supplied

All Sonographers performing this scan have obtained a certificate of competence with the Fetal Medicine Foundation.

Fetal well-being and reassurance

These scans are carried out from 14 weeks onwards. The scans are to check that the pregnancy is progressing well. The heart rate is checked and measurements are taken to check fetal growth.

Fetal sex (20+weeks)

This scan is best performed after 20 weeks. We can determine the gender of the baby with an accuracy of about 99%. Black and white 2D images, DVD & report supplied

Fetal Anomaly Scan (20-24 weeks)

This scan is performed between 20 and 24 weeks of pregnancy. It is a structured examination of the baby's anatomy following guidelines from the Royal College of Obstetricians and Gynaecologists. The checklist includes; the head, spine, heart and kidneys. This scan also allows for the detection of problems such as cleft lip. The placental site is also checked.

Black and white 2D images, DVD & report supplied

Growth scan 24-42 weeks

Some obstetricians advise that an ultrasound scan to assess fetal size and wellbeing is offered to all women at about 34 weeks of pregnancy. Repeat scans are necessary to document growth rates. Others reserve such scans for those women who have had previous complications of pregnancy such as pre-eclampsia, growth restriction, diabetes, still birth, and for those women who develop a problem during the course of their current pregnancy.

This scan aims to determine the growth and health of the fetus by:

  • Measurement of the size of the fetal head, abdomen and thigh bone and calculation of an estimate of fetal weight
  • Examination of the movements of the fetus
  • Evaluation of the placental position and appearance
  • Measurement of the amount of amniotic fluid
  • Assessment of blood flow to the placenta

Black and white 2D images, DVD & report supplied

We also have close links with:

  • local Specialists at the Royal Berkshire Hospital (Reading)
  • Consultant Mr L. Impey, John Radcliffe Hospital (Oxford) www.oxfordfetalmedicine.co.uk
  • Professor Mr Kypros Nicholaides, Fetal Medicine Foundation www.fetalmedicine.com