OSCAR - One Stop Clinic for Assessment of fetal Risk

The First Trimester Nuchal Scan and OSCAR

The OSCAR is offered to women between 11 and 14 weeks of pregnancy to assess the risk of Down's syndrome and includes.

1. Combined blood testing and a nuchal scan during one visit.
2. Results and advice on the same day.
3. One stop - the entire procedure usually takes about 1 to 1.5 hours.

How is the risk of Down's Syndrome assessed?

Fetuses have a small amount of fluid at the back of their neck (Nuchal Translucency), which can be measured by a nuchal scan. Research has shown that this amount of fluid is related to your risk of DS.
 
Downs Syndrome screening is a combination of non-invasive tests which gives you a risk of having a Down's baby. The risk assessment is based on the following factors:

• The mother's age 
• The level of two substances (a protein and a hormone) in the mother's blood
• The baby's length measured at ultrasound scanning
• The thickness of the fluid filled space at the back of the baby's neck measured on nuchal scan

At SMI we provide a comprehensive service to assess the risk of your baby having Down's syndrome with a high accuracy of %95

OSCAR at BP/SMI  - What to expect

• On arrival a registration form will be completed
• A blood sample will be taken from a vein in your arm and sent to our laboratory for measurement of two substances; βhCG is a hormone and PAPP-A a protein which are produced by the placenta. The levels of these substances give a part assessment of your risk of Down's syndrome. Analysis of this blood sample takes around 40 minutes.
• Whilst your blood is being analysed you will have a nuchal scan to measure the nuchal thickness - see below for other information obtained during this scan. The nuchal scan is generally performed by scanning through your tummy, however if your baby is in a difficult position an internal (trans-vaginal scan) may be needed. There is no risk to the pregnancy during this scan. 
• The results of the tests are analysed by computer to determine your risk of your pregnancy being affected by Down's syndrome.
• Discussion of the results and what you should consider next.
• You will be given a printed report of the result and an nuchal scan picture of your baby 
• We recommend and can arrange that a copy of the report is sent to your midwife, GP or Obstetrician
• If required advice on referral onto a Consultant in fetal medicine / Obstetrics for further advice and investigation on amniocentesis or CVS (Chorionic Villus sampling) 

When to have the nuchal scan

The nuchal scan needs to be performed between 11 and 13 weeks + 6 days of gestation.

The nuchal scan measurement relies on an accurate knowledge of your gestational age (age of fetus). If you are uncertain of your dates we recommend you have a dating scan before attending the OSCAR - these are available at all our clinics.  If you are unexpectedly outside the dates for a nuchal scan you will not be able to have the test. If you are less than 11 weeks we can rearrange your appointment. Unfortunately, however, you will be liable for an additional charge for this dating scan. 

Accuracy of tests

Screening for Down's syndrome by combining maternal age, Nuchal scan at 11- 14 weeks and  blood testing (maternal serum free βhCG and PAPP-A) picks up around 90% of high risk pregnancies and makes it the most reliable non-invasive risk assessment for Down's syndrome.
At Baby Premier our current rate of detection is 95% (outcome audit data Feb 08)

Who performs the scan?

All NT scans are performed by an Advanced Practitioner in Medical  Diagnostic Ultrasound or medical Consultant Obstetricians who holds the Certification for nuchal scanning as regulated by the Fetal Medicine Foundation.  The FMF, which is a UK registered charity, has established a process of training and quality assurance for the appropriate introduction of NT screening into clinical practice. Requirements for certification are outlined at www.fetalmedicine.com

Referral

Although it is not necessary to have a referral from your GP or midwife we recommend that you tell them you are having the screening assessment. We will ask you if you want the reports sending on to you midwife, GP or Consultant Obstetrician, which we recommend.