Contraction Stress Test: When and why a pregnant woman should take it

Some pregnant women who have issues might need a contraction stress test. However, it’s not so usual. A biophysical profile or a nonstress test is usually administered. If those results indicate a potential problem, your doctor can suggest a CST as a follow-up test.

Contraction Stress Test

A contraction stress test (CST) is a type of testing for expectant mothers.  Through uterine contractions, it keeps an eye out for signs of stress in your baby.

During the test, your uterus will contract due to a hormone your doctor will deliver. Despite the fact that they resemble labor contractions, these contractions typically do not start labor.

During labor contractions, your baby’s blood and oxygen levels momentarily drop. The majority of infants can handle this reduction. But some infants’ heart rates drop even after the contraction is over. 

A CST simulates labor contractions to test if your baby can endure the drop in blood and oxygen levels.

How a contraction stress test is done?

Two belts will be around your midsection as you lay down. The heartbeat of your unborn kid is measured by one, and labor pains are detected by the other. 

Your doctor might administer an IV infusion of oxytocin to start labor or may advise you to stimulate your nipples through your clothing as an option for inducing birth. 

As you wait, the monitors will start to record your baby’s heartbeat and your contractions. It takes roughly two hours to complete the exam. There’s a chance you’ll have painful contractions.

CST is mostly safe, despite the fact that it can occasionally lead to early labor. Women who have had a previous C-section, have placenta previa, or are at higher risk for uterine rupture are at higher risk for the test. Nevertheless, your doctor will recommend if it’s best to take the contraction stress test or not. 

Your doctor may recommend you take a contraction stress test if:

• Your pregnancy is high-risk.
• You’re diabetic.
• You experienced difficulties during a prior pregnancy.
• The 40th week of your pregnancy has passed.
• Your non stress test or biophysical profile results are unusual

Women may have a contraction stress test at 32 weeks or later. Before that, the test might not be secure. The frequency of the test changes depending on the situation. Consult your doctor.

Positive Contraction Stress Test

CST outcomes could be favorable or unfavorable. They might also be unsure. Your doctor might want to repeat the test in a few days if the results are unclear:

• Positive Contraction Stress test

Abnormal data show that the fetal heart rate slows and remains slow after the contraction for more than half of the contractions.

• Contraction Stress Test Negative

In a healthy test, the fetal heart rate does not go down before, during, or after contractions.

If your test results are positive, your baby might not be able to survive the stress of labor contractions. Your doctor could suggest other tests, such as another contraction stress test a week or two later. If you continue to have positive contraction stress test results, your doctor may suggest a cesarean delivery.

Contraction Stress Test Negative

Results from the CST are valid for seven days. If your contraction stress test is negative and your pregnancy has persisted for more than a week since your last CST, your doctor may advise having another CST done in a few days to a week.

Your doctor might suggest cesarean delivery or induction if the results of the CST are positive. According to studies, a positive contraction stress test result is a reliable indicator of abnormal fetal heart rate patterns after birth.

READ MORE: 

Non Stress Test in pregnancy – What can it tell you

Pregnancy Guide: When to start antenatal care and take an antenatal visit

The Pap Smear and pregnancy: Everything you need to know

Contraction Stress Test vs Non Stress Test

Here’s the difference between non stress test and contraction stress test:

In a non-stress test, your baby’s heart rate is monitored without applying any external stress. A contraction stress test examines your unborn child’s heart rate during times of stress.

Your healthcare provider will give you thorough advice on how to be ready for a contraction stress test. Typically, you wait four to eight hours before the test before eating or drinking anything.

Risks of a Contraction Stress Test

In addition, CST has some risks to it. You and your doctor will discuss the benefits and drawbacks of CST.

It poses the following risks:

• Possibility of resuming labor
• Pitocin may cause fetal discomfort.
• Discomfort

Hospital staff will closely monitor you before, during, and after the test. A CST might not be recommended if you are at risk for premature labor or have placenta previa.

People with multiples (twins, triplets, or more) may be unable to take a contraction stress test. If you are expecting multiples, the test has a higher chance of inducing labor.

Contraction Stress Test Alternatives

If a CST is not an option for you, your doctor may combine a number of different fetal monitoring procedures to assess the health of your unborn child, including:

• Non stress Test

A nonstress test is a common prenatal test to assess a baby’s health. During a non-stress test, the infant’s heart rate is monitored to determine how it responds to movement. Nonstress refers to the fact that no attempts are made to stress the infant throughout the examination.

A non-stress test can be carried out after 26 to 28 weeks of pregnancy. Results from particular non-stress tests may indicate that you and your newborn need further monitoring, testing, or special care.

A nonstress test is not intrusive and doesn’t physically injure you or your unborn child.

• Biophysical Profile

A biophysical profile (BPP) test, which assesses the fetus’s physical state, includes a nonstress test and ultrasound. The fetal heart rate is monitored in response to the fetus’ movements during a non-stress test (NST).

An ultrasound diagnostic technique uses high-frequency sound waves to visualize the fetus. Biophysical profile testing is routinely done in the third trimester of pregnancy.

• Doppler ultrasound exam

In addition, doppler ultrasounds are noninvasive diagnostic procedures that evaluate blood flow via your blood vessels by reflecting high-frequency sound waves off moving red blood cells. Normal ultrasounds cannot show blood flow.

Furthermore, a Doppler ultrasound can determine how swiftly blood flows by measuring the rate of pitch shift (frequency). This test may be used as an alternative to more invasive procedures like angiography, which entails injecting dye into the blood vessels to make them visible on X-ray imaging.

Using a transducer, a sonographer applies pressure to your skin across the area of your body being scanned. It will move from one location to another as necessary.

A Doppler ultrasound may also be used by your doctor to check for artery damage or to monitor a particular vein and artery therapy.

Consult your doctor about the contraction stress exam

You should discuss any concerns with your doctor, including questions about the test. Your doctor will explain what the results might suggest and what should be done next.

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