Second Trimester Tests During Pregnancy

Medically Reviewed by Dr. K on 21 April 2021

Table of Contents:

  1. Second Trimester Tests During Pregnancy
  2. Maternal serum alpha-fetoprotein (MSAFP) and multiple marker screening
  3. Non-Invasive Prenatal Testing (NIPT) screening
  4. Ultrasounds
  5. Glucose Screening
  6. Amniocentesis
  7. Fetal Doppler Ultrasound
  8. Fetoscopy

 

Second Trimester Tests During Pregnancy

 

There are many tests that are required to be conducted in the second trimester of pregnancy. 

 

Maternal serum alpha-fetoprotein (MSAFP) and multiple marker screening

 

In the second trimester, one or the other is routinely offered. This is an optional genetic screening test; as with other screening tests, discuss the benefits and drawbacks with the doctor to see whether it is appropriate for you. The MSAFP test determines how much alpha-fetoprotein, a protein released by the foetus, is present. Abnormal levels suggest the probability (but not the confirmation of existence) of Down syndrome or a neural tube disorder like spina bifida, and may be verified using ultrasound or amniocentesis. 

The triple examination is where blood taken for the MSAFP test is often used to monitor quantities of the hormones estriol and hCG. The quad marker is created when a marker named inhibin-A is applied to the screen. The quad marker test greatly improves Down syndrome diagnosis rates. Since the test detects around 75% of neural tube defects and 75% – 90% of Down syndrome cases (depending on the mother's age), many women will receive a false-positive result. An abnormal reading will occur in around 3% to 5% of people who have the screening exam, although only a tiny number of those women will have a child with a genetic problem.

Non-Invasive Prenatal Testing (NIPT) screening

This cell-free foetal DNA examination may be performed as early as 10 weeks after conception. A blood examination is used to determine the volume of free foetal DNA in a mother's blood. The exam is believed to be capable of detecting 99% of all Down syndrome births. It even looks for chromosomal defects in some people.

 

Ultrasounds

Ultrasounds (sonograms) are often given during week 20, although they may be performed at some point during the pregnancy. A sonogram can be used to confirm a due date, scan for numerous foetuses, investigate abnormalities like placenta previa (low-lying placenta) or poor foetal development, or diagnose malformations like cleft palate. If there are any unusual tests with a genetic abnormality, you might be sent to a doctor or undergo further genetic examination. During the treatment, a tube is moved around the abdomen that sends sound waves to a computer display, creating an impression of the uterus and foetus. New three-dimensional sonograms give you a clearer view of your foetus, but they're not accessible everywhere, and it's unclear if they're any stronger than two-dimensional images in terms of promoting a stable pregnancy or delivery.

 

Glucose screening

This is a standard screening for pregnancy-induced diabetes, which may result in large babies, difficult deliveries, and health complications for both you and your infant. It is usually administered between 24 and 28 weeks. This test determines the blood sugar level an hour after drinking a special drink. If the number is too big, you'll be asked to undergo a more sensitive glucose-tolerance test, in which you consume a glucose solution on an empty stomach and get your blood drawn every hour or so for 2-3 hours.

 

Amniocentesis

This optional test is normally done between 15 and 18 weeks of pregnancy for people who are 35 or older, have a higher-than-usual chance of genetic abnormalities, or have suspicious MSAFP, multiple marker, or cell-free DNA test findings. The treatment entails sticking a needle through the amniotic sac and withdrawing fluid containing foetal cells via the abdomen. Neural tube abnormalities and genetic anomalies may be detected by analysis. The rate of miscarriage following amniocentesis differs based on the doctor doing the treatment, although it typically ranges from 0.2% to 0.5% at 15 weeks. Nevertheless, the test will diagnose 99% of neural tube defects and almost 100% of some genetic abnormalities.

 

Fetal Doppler Ultrasound

Sound waves are used in a Doppler ultrasound procedure to measure blood as it passes into a blood vessel. Blood supply to the placenta and pregnancy may be determined using foetal Doppler ultrasound.

 

Fetoscopy

Fetoscopy is a procedure in which a practitioner tests the embryo using a small, lightweight device known as a fetoscope. Fetoscopy may identify disorders or abnormalities that other studies, such as amniocentesis, ultrasound, or chorionic villus screening, are unable to detect. Fetoscopy is a rare operation and is only recommended where there is a far higher-than-normal possibility that the baby may have an abnormality. It carries major dangers for both the mother and the child.

Sources

Referenced on  10.4.2021

  1. Gabbe: Obstetrics-Normal and Problem Pregnancies, 4th edition, 2002.
  2. WebMD Medical Reference provided in collaboration with The Cleveland Clinic: “Pregnancy: Your Guide to Pregnancy."
  3. WebMD Medical Reference from Healthwise: “Rh Sensitization During Pregnancy;" “Doppler Ultrasound;" and “Fetoscopy."
  4. https://www.webmd.com/baby/guide/second-trimester-tests#1

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