FAQs ON MATERNAL MARKERS AND PlGF TESTING

Why is a Dual Marker not done when one foetus is aborted in case of twin pregnancies?

If one foetus is aborted, we need to look for the foetal pole. If the foetal pole is present in the demised twin, the dual test is not possible as there will be production of substances (PAPP-A & Free βhCG) from the demised twin and the resulting interpretation will be erroneous. Foetal pole needs 8-9 weeks to close in cases where one foetus in aborted. If there is no foetal pole we can take the pregnancy as a singleton and the dual test can be processed.

Why do we report single risk in monochorionic twins although the CRL (Crown-rump Length) and NT (Nuchal Translucency) values are different?

Monochorionic twins originate from the same embryo, so they are assumed to be genetically identical although there is the difference in biometry.

What is the benefit of NT value measured using FMF (Fetal Medicine Foundation) guideline?

FMF guidelines provide a standardized methodology for NT measurement. This is paramount in maintaining the sensitivity of the combined screening as it contributes significantly (about 70% to the 91%) detection rate in the dual test.

What is Corrected MoMs?

Corrected MoMs are MoMs with weight corrections.

  • Weight correction should be applied to all analytes in Down’s syndrome screening
  • Evidence shows that weight correction improves the detection rate
  • Multiple median values can be significantly affected by weight correction
What is the importance of the sample collected on the DBS card over serum?

Free βhCG is more stable and intact on the DBS card. Also dissociation from free βhCG occurs slow on the DBS card.

Why is maternal screening not done between 14 and 15 week of gestation?

One of the most discriminating markers for NTD is AFP which is best accessed from the 15th week for the quadruple test. Hence, the window of the 14 to 15 week is not ideal for dual or quadruple test.

Why do we not report Patau syndrome (T13) in 2nd trimester screening?

Sensitivity of patau syndrome is very low in the 2nd trimester as pregnancies diagnosed with T13th end in miscarriages between 12 to 15 week of gestation.

What is the difference between LifeCycle software, ssdw, Austria and Prisca?

LifeCycle risk calculation engine is a comprehensive informatics package for maternal health monitoring and risk assessment. An accessible patient data management system is coupled with a flexible risk calculation engine, which can be configured to meet local variations. Because the system has been fully validated and all calculation methods, algorithms and values are supported by the current published literature, LifeCycle gives full confidence in a maternal risk assessment program.

Are there any insights on Pre-eclampsia (PIGF- PLACENTAL GROWTH FACTOR)?

Pre-eclampsia is a sudden increase in blood pressure and protein in the urine after the 20th week of pregnancy. Pre-eclampsia can lead to eclampsia, or convulsions, posing serious health implications for the mother and the baby. Symptoms of pre-eclampsia may include:

  • High blood pressure (≥140/90 mmHg)
  • Swelling in the face and hands (and feet, although swollen feet are common during pregnancy)
  • Weight gain of more than 2 kgs in a week
  • Other problems such as headache, blurred vision, abdominal pain and nausea
What is MAP & uAD and what is their relevance in PlGF test?
  • Mean Arterial Pressure (MAP) – Accurate measurement of blood pressure in pregnant women is particularly important when attempting to identify early signs of pre-eclampsia. As a means of prediction, it has been suggested that the MAP, whether measured in the first or second trimester, is better than systolic blood pressure, diastolic blood pressure, or an increase of blood pressure. In clinical practice MAP measurement in the first trimester may not make a clinical impact in isolation but could be suitable for use with other markers, including maternal serum markers, to improve the accuracy for estimating the risk of pre-eclampsia.
  • Uterine Artery Doppler (uAD) – The uterine artery Doppler can be evaluated by direct visualization, i.e. examining the characteristics of the waveform to determine if nothing is present or absent, or by quantifying the waveform by measuring the blood flow velocity at peak systole (maximal contraction of the heart) and peak diastole (maximal relaxation of the heart). These values are then computed to derive a ratio. The most common approach is to measure the Resistance Index (RI) in which the peak of systole is divided by the sum of systole and diastole.
  • RI= systole/ (systole + diastole)
  • In early pregnancy, the peak flow at diastole is less than later in pregnancy. Therefore, as the duration of pregnancy increases, the amount of blood flowing in the umbilical artery increases during diastole.
Test CodeTest NameSampleComment/ Description
SGO61Dual Marker Test: (11 – 13.6 weeks) PAPP-A, Free ßhCG2 ml serum / DBS CardNT by USG report (NT & CRL values) and brief clinical history required
SGO62Triple Marker Test: (15 – 21.6 weeks) AFP, ßhCG, uE32 ml serumUSG report and brief clinical history required
SGO63Quadruple Marker Test: (15 – 21.6 weeks) AFP, ßhCG, uE3, Inhibin – A2 ml serumUSG report and brief clinical history required
PRF2400Integrated Test: Dual Marker (First Trimester Screening) & Quadruple Marker (Second Trimester Screening)2 ml serumNT by USG report in 1 trimester & USG report in nd 2 trimester and brief clinical history required

Sequential Test: (Combined risk evaluation even if Dual Marker is done seperately)

Test CodeTest NameSampleComment/ Description
SDO61Dual Marker Test: (11 – 13.6 weeks) PAPP-A, Free ßhCG2 ml serumNT by USG report and brief clinical history required
SDO63Quadruple Marker Test: (15 – 21.6 weeks) AFP, ßhCG, uE3, Inhibin A2 ml serumUSG report and brief clinical history required, (Patient needs to carry Dual Marker report)
SDO63Prenatal BoBs (Aneuploidies + Microdeletion)3 ml Amniotic Fluid / Chorionic VilliBrief clinical history required
SDO65KaryoLite BoBsPlacental biopsy without blood clot in normal special container provided by LabBrief clinical history required
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