Other Antenatal Screening
As well as the Harmony® prenatal test Clinical Labs also offers the First Trimester Screen (FTS), to identify women with an increased risk of carrying a fetus affected with a chromosomal aneuploidy such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18) or Patau syndrome (Trisomy 13). Additionally, the placental growth factor blood test is now an option with the FTS, to screen women for early-onset pre-eclampsia.
First Trimester Screening is the current recommended screening program to identify women with an increased risk of carrying fetus affected with chromosomal aneuploidy such as Down syndrome (Trisomy 21), Edwards syndrome (Trisomy 18) or Patau syndrome (Trisomy 13). Combined FTS (cFTS) includes the Multiple of Medians (MoMs) of two blood chemistry results, pregnancy-associated placental protein-A (PAPP-A) and free β-human chorionic gonadotropin (free β-hCG), along with the ultrasound Nuchal Translucency (NT) measurement to assess the risk of aneuploidy. This assessment has 85-90% sensitivity and 95-97% specificity for Down syndrome. Australian Clinical Labs specialise in Harmony testing and First Trimester Screen testing. Please see a comparison of the two tests in the table below.
first trimester screen
|Partial Medicare rebate||No Medicare rebate|
|Detection rate 85-90%||Detection rate>99%|
|False positive rate 3-5%||False positive<0.1%|
|Pre-eclampsia risk assessment (additional fee)||Pre-eclampsia risk assessment unavailable|
|Sex of the baby unavailable||Sex of the baby|
|Sex chromosomal aneuploidy unavailable||Sex chromosomal aneuploidy|
|Ultrasound essential for risk analysis||Ultrasound recommended|
|Cannot be validated if number of fetuses>2||Cannot be validated if number of fetuses>2|
HOW TO ORDER
Health practitioners can order FTS for patients using the Australian Clinical Labs Antenatal request form. Please ensure you document on the request form the following:
- Calculated gestational age and clinical due date
- Number of fetuses (if known)
- Patient weight, height, ethnicity and family history
It also requires history of non-insulin dependent diabetes mellitus (NIDDM) and smoking. For IVF patients, the source of egg (patient or donor), patient age at egg retrieval and the date of egg extraction will also be required. Please note that health practitioners can also order Non-Invasive Prenatal Testing (NIPT-Harmony) on the same antenatal request form. Ask the patient to present at one of the many conveniently located Australian Clinical Labs collection centres.
The blood chemistry test can be performed between 9+ and 13+6 weeks of gestation (ideally at 10+ weeks). One serum sample is required. The structural Nuchal Transluency ultrasound (NT scan) should be performed between 11 and 13+6 weeks (ideally at 12 weeks).
Important Note: If PIGF is also requested for Early-Onset Pre-Eclampsia (EO-PE) screening, gestation MUST be between 11-13+6 weeks.
Results will be available 2 business days following the ultrasound scan date.
For the cost of the FTS please call 1300 134 111 or 1300 367 674 (WA). Medicare rebate available (subject to Medicare Rebate Criteria being met).
Pre-eclampsia (PE) is one of the most common serious complications of pregnancy. Early identification of PE is an important step towards improved management and outcomes of such cases. Placental Growth Factor (PlGF) is the preferred serum marker for pre-eclampsia prediction.
As part of our Antenatal Screening offerings, Australian Clinical Labs is now offering the Placental Growth Factor (DELFIA Xpress® PlGF 1-2-3™ assay) blood test. Along with the Combined First Trimester Screening and Harmony Non-Invasive Prenatal Testing (NIPT), PlGF is an additional screening marker for Early-Onset Pre-Eclampsia (EO-PE) in pregnancy.
PlGF is a glycoprotein that belongs to the vascular endothelial growth factor (VEGF) subfamily. It is a potent angiogenic factor. It is expressed in the villous syncytiotrophoblast and in the media of larger stem vessels in the human placenta. PIGF, together with VEGF, regulates the development of the placental vasculature, and the result depends on intra-placental oxygen pressure 1,2,3.
PlGF concentrations increase throughout pregnancy, peaking during the third trimester, and falling thereafter, probably as a consequence of placental maturation. In pre-eclampsia or intrauterine growth restriction (IUGR), changes in expression or function of PIGF, as well as some other angiogenic factors, may interrupt the function of the utero-placental unit, and thus contribute to many adverse obstetric outcomes 1,2,3.
The PlGF test can be offered to pregnant women of any age or risk category. It can be ordered for all naturally conceived or in vitro fertilisation (IVF) singleton or twin pregnancies, including those with egg donors. The PlGF test is currently viewed as a screening test and clinical interpretation is always recommended 1,2.
The COMPARE (6) study states that the high negative predictive values (NPV) support the role of PlGF-based tests as ‘rule-out’ tests for pre-eclampsia. Among the tests compared, the DELFIA Xpress® PlGF 1-2-3™ assay has the highest NPV. Recently, studies 3,4,5 showed that the administration of aspirin in pregnancies, at high risk of pre-eclampsia reduces the length of stay in the neonatal intensive care unit (NICU) by about 70% mainly through the prevention of early pre-eclampsia.
- Royal College of Obstetricians and Gynaecologists patient information leaflet, Information for you: Pre-eclampsia. RCOG Patient Information Committee, London, UK, Aug 2012.
- Rolnik DL et al. (2017) Nicolaides KH. ASPRE trial: performance of screening for preterm pre-eclampsia. Ultrasound Obstet Gynecol Jul 25.
- Bujold et al. (2010) Prevention of preeclampsia and intrauterine growth restriction with aspirin started in early pregnancy: a meta-analysis. Obstet Gynecol. 2010;116:402-414.
- Roberge et al. (2012) Early administration of low-dose aspirin for the prevention of preterm and term preeclampsia: a systematic review and meta-analysis. Fetal Diagn Ther.2012;31(3):141-146. doi: 10.1159/000336662. Epub 2012 Mar 21.
- Wright et al. (2018) Secondary analysis of ASPRE trial. Am J Obstet Gynecol. 612.e6.
- McCarthy FP et al. (2019) Comparison of three commercially available placental growth factor tests in women with suspected preterm pre-eclampsia: the COMPARE study. Ultrasound Obstet Gynecol 2019;53:62-67.
HOW TO ORDER
Doctors can order the test by using the Australian Clinical Labs request form. Blood samples can be collected at any of our Australian Clinical Labs pathology collection centres.
When to offer: The optimal time for screening is between 11 and 13+6 weeks of gestation.
Who to offer: Patients with high blood pressure, advanced age pregnancy, high BMI, positive history of pre-eclampsia, diabetes or kidney disease, multiple pregnancies or IVF assisted pregnancies.
Specimen Requirements: Plain tube or serum gel 7 ml.
The Placental Growth Factor (PlGF) test costs $50. No Medicare rebate available.