What Tests Are Done in a Quadruple Marker for Women in Pregnancy?

Doctors often recommend various blood tests during pregnancy so that they can check the mother's health and also detect if there are any issues with the fetus. Among these tests, the quadruple marker test offers particularly useful details of the fetus and can assist your doctor in determining if the baby is likely to have Down syndrome, trisomy 18, or other abnormalities after birth. 

Many women are unaware of how important these tests are because it is always better to screen for birth defects when there is still time to make a decision about the continuation of the pregnancy.  

What is The Quadruple Marker Test?

A blood test known as a quad screening or quadruple marker is used to find any chromosomal abnormalities or birth problems in an unborn child during the second trimester of pregnancy. The quadruple marker test can assist in determining the fetus's likelihood of developing specific diseases, such as Down's syndrome, Edward's syndrome, and neural tube abnormalities. It is usually conducted between weeks 14 and 22 of pregnancy, and the existence of multiple fetuses might also be detected using this test.  

The Types of Tests Done Under Quadruple Marker

The quadruple marker test analyzes four different proteins and hormones during pregnancy. The growing fetus's risk of birth abnormalities is depicted by the high and low levels of these proteins and hormones, which gives a doctor vital information to prescribe more screening if necessary. The following four tests are done under this procedure: 

• Unconjugated estriol (UE)
  The placenta gives the developing infant the nutrition it needs and it also produces the hormone estriol. A high likelihood of having a child with Down syndrome is indicated by a low level of estriol and this is the main reason behind performing a quadruple test in pregnancy.
  
  
• Alpha-fetoprotein (AFP)
  The liver of the fetus generates AFP and high values may indicate an abdominal wall abnormality such as gastroschisis or omphalocele. It can also show a neural tube lesion such as spina bifida or anencephaly. However, it can also indicate that you are expecting twins or that your pregnancy is further advanced than you initially believed. A fetus with Down syndrome may have an increased chance of having low AFP levels, and that diagnosis can be useful in determining the next steps.
  
  
• Human chorionic gonadotropin (hCG)
  Numerous hormones, including LH, FSH, and TSH, share this glycoprotein, which has an alpha subunit. The beta subunit of hCG, which has the greatest resemblance to LH, enables the hormone to perform its job of preserving pregnancy by enabling the corpus luteum to continue functioning as a source of progesterone. After that, the placenta manufactures this hormone until the baby is ready to be delivered. Hence, the concentration of hCG peaks during the first trimester and then about doubles every 48 hours before starting to decline at the end of the first 13 weeks of pregnancy.
  
  Trisomy 18 causes low amounts of hCG, but Down’s syndrome and multiple pregnancies are associated with high levels. Since this test is typically conducted in the second trimester, when the levels start to decline, it may also show a false positive if the fetus is believed to be older than it actually is. Additional causes of a high hCG level include triploidy, hydrops fetalis, and fetal loss, all of which are serious conditions that need medical intervention.
  
  
• Inhibin-A
  The ovarian granulosa cells and the testicular Sertoli cells, which have a nutritional role, are the source of this glycoprotein. Its subunits are alpha and beta, and the latter is present in distinct forms of the hormone inhibin. By functioning as a feedback mechanism on the pituitary gland and brain, inhibit-A regulates the production of ovarian hormones and influences several aspects of fetal development. As the pregnancy goes on and the fetus becomes bigger, the placenta produces it in greater quantities.
  
  While abnormalities in inhibin-A levels are similar to those in hCG and have the same relevance, they contribute to the increased specificity and sensitivity of the diagnostic use of quadruple test in pregnancy.

Abnormal Quadruple Marker Test Result Implications  

Results from a quad marker screen that fall outside of the usual range may not always indicate that something is wrong with your pregnancy because the quad marker test is not intended to diagnose any specific issue. It is a screening tool that can only determine your likelihood of giving birth to a child who has certain birth abnormalities. Further testing, such as an ultrasound or amniocentesis, may be required if the findings of the quad marker screen fall outside of the normal range.

Of 1,000 pregnant women, about 50 will have quad marker screen findings indicating a higher chance of a birth abnormality in the unborn child. If the results of your quad marker screen test are abnormal, ultrasounds are frequently advised because they enable the medical professional to inspect the fetus visually. They can then confirm your gestational age and the number of fetuses you are carrying.

According to research, quad marker screen tests can accurately detect around 75% of Down syndrome instances in women under 35 and approximately 90% of cases in pregnant women over 35. In the event that your quad marker screen test yields a positive result, you should proceed with further testing in order to obtain a precise diagnosis of the problem. Targeted ultrasound, Amniocentesis, Chorionic villus sampling, and Non-invasive prenatal testing are all performed in this process. 

What Fetus Defects Can a Quadruple Marker Test Detect?

The test assesses the likelihood of having a child with any of the following conditions:

• Down syndrome (Trisomy 21): This is a chromosomal abnormality that results in developmental delays and a lifetime of brain impairment in the baby. Short, stocky physical characteristics, such as a short neck, flattened facial features, tiny hands, delayed speech and language development, and concentration issues, are some of the symptoms associated with Down syndrome.
  
  
• Trisomy 18: It is a chromosomal abnormality that results in significant developmental delays, and abnormalities in the body structure, and is frequently deadly.
  
  
• Spina bifida: A birth condition that results from a part of the neural tube not developing or closing properly, leading to abnormalities in the spine, bones, and vocal cord.
  
  
• Abdominal wall defects: These birth disorders occur when the baby's intestines or other abdominal organs protrude through the belly button. 

After receiving a quadruple marker test normal report you can be sure that your baby is growing up healthy. 

Final Remarks

The quadruple marker test is used to find any chromosomal abnormalities in an unborn child during the second trimester (14 and 22 of pregnancy). A quadruple marker test normal report indicates that there is no elevated risk of birth abnormalities in the offspring. The fetal development and other factors will determine whether or not the healthcare provider recommends additional screening tests. The quad screening test does not determine if a newborn has Down’s syndrome or neural tube abnormalities based on abnormal levels of certain hormones and proteins. For expectant mothers, this test enables physicians to confirm a diagnosis and offer helpful information about related concerns. 

If you are in need of a pregnancy-related test, contact Pathkind Labs and get the test done!