Contraction stress test (CST)

Definition

A Contraction Stress Test (CST) is a prenatal test that helps determine how well a baby will cope with the stress of labor and delivery. The test monitors the baby’s heartbeat in response to uterine contractions, whether natural or induced. If the baby’s heart rate decreases during contractions instead of increasing, it could indicate that the baby might not be getting enough oxygen and may suggest a problem with the placenta.

Key Takeaways

The Contraction Stress Test (CST) is a prenatal test used to check how the baby’s heart rate responds to contractions. It is often performed in the last trimester of pregnancy.
During the CST, the mother’s contractions are induced, usually either by physical stimulation or medication, and the baby’s heart rate is monitored. This provides valuable information about the health of the fetus and how it may react during labor.
While the CST can provide important insights, it may also pose some risk factors. It can potentially initiate labor and is usually recommended only when there is a concern about the baby’s health, and other safer tests have not provided conclusive results.

Importance

The Contraction Stress Test (CST) is a crucial element of motherhood as it is designed to evaluate how well a baby will cope with the contractions during childbirth.

This test measures the baby’s heart rate in response to induced contractions in the mother, providing vital information on whether the baby’s oxygen supply might get impaired under the stress of contractions during labor.

Thus, a CST aids in preemptively identifying potential distress and complications during delivery, allowing healthcare professionals to make informed decisions about the need to expedite the delivery or opt for a cesarean section.

Hence, it plays a significant role in ensuring the safety of both mother and baby during childbirth.

Explanation

The contraction stress test (CST) is a prenatal examination used during pregnancy to assess how a baby’s heart responds to the stress induced by uterine contractions. It is also commonly referred to as an oxytocin challenge test. The CST is primarily intended to evaluate a baby’s heart rate and can aid in identifying potential complications or problems.

The reason why this exam might be carried out is due to existing conditions or complications, like gestational diabetes, a history of stillbirth, or when a mother is past her due date. In essence, the CST provides insight into how well the baby may cope during labor. When contractions occur, there is momentarily less oxygen available to the baby, and for most healthy babies, this is not an issue.

But if the baby’s heart rate decreases during or after a contraction, it may suggest that the baby isn’t receiving enough oxygen during these periods. Therefore, the contraction stress test serves important predictive value for the care team in terms of planning for safe delivery. If the test is non-reactive or positive, it may spark discussions about early delivery or intervention methods to ensure the baby’s well-being.

Examples of Contraction stress test (CST)

Example 1: Jennifer is in her 36th week of pregnancy and her health care provider has noticed reduced fetal movement. Jennifer’s doctor may recommend her to undergo a Contraction Stress Test (CST) to ensure her baby’s health and well-being. During the test, Jennifer’s contractions are stimulated using certain medications. Doctors then monitor the baby’s heart rate response to these contractions, thereby providing assurance about the infant’s ability to cope with the stress of labor.

Example 2: Martha, a 42-year-old woman, is pregnant with her first child and is experiencing irregular contractions. Her obstetrician advises her to have a Contraction Stress Test (CST). Through this test, doctors aim to evaluate how the baby’s heart rate reacts to contractions. This helps them better understand if the baby would be able to handle the stress of a natural delivery.

Example 3: Sara, who is at 38 weeks of gestation, has a history of diabetes, making her high-risk pregnancy. To ensure her baby’s health and safe delivery, her doctor suggests conducting a Contraction Stress Test (CST). This test helps in checking if the baby’s oxygen supply gets affected during contractions. With the CST results, Sara’s healthcare team will be better able to plan for a safe delivery.

FAQs about Contraction Stress Test (CST)

What is a Contraction Stress Test (CST)?

A Contraction Stress Test (CST) is a procedure performed during pregnancy to evaluate the baby’s heart rate to see if it decreases after a contraction. It’s a way to check on how the baby will cope during labor.

How is a CST conducted?

The test begins with you lying on your left side. Two sensors are strapped to your abdomen, one to measure contractions, and the other to record your baby’s heart rate. The contractions are induced either by nipple stimulation or through medications.

When is a CST performed?

CST is typically performed after 34 weeks of gestation but is ideally conducted in the final weeks leading up to your due date. The test is only performed when medical professionals need to check if a baby can handle the stress of contractions before labor is induced.

What do the results of CST mean?

If the baby’s heart rate does not decrease during or after contractions, the result is “negative,” which is what you hope for. If the heart rate decreases too much for too long, the result is “positive,” indicating that the baby may not be getting enough oxygen during contractions.

What are the risks associated with CST?

There can be minor risks associated, such as premature labor or infection, especially if the membranes are ruptured. In rare cases, the test can cause severe fetal distress leading to an emergency C-section. Always discuss these risks with your healthcare provider.

Related Motherhood Terms

Braxton Hicks contractions: These are known as ‘false labor’ contractions, typically felt intermittently throughout pregnancy and increasing in frequency and intensity towards the end of the third trimester.
Non-Stress Test (NST): It’s another type of antenatal surveillance test like Contraction Stress Test (CST), used to measure the baby’s heart rate and response to its own movements.
Tocodynamometer: This is a device used during a CST to measure the frequency and duration of uterine contractions.
Fetal Heart Rate Monitor: An important tool used in CST to monitor the heart rate of the baby during contractions to check on its well-being.
Oxytocin: This is a hormone that is often administered artificially to induce or augment labor contractions for a CST when they are not occuring naturally.

Sources for More Information

Mayo Clinic is a reliable source that provides useful medical information including content about Contraction Stress Test.
WebMD boasts comprehensive guides about various health-related topics.
Healthline offers clear, thorough articles about a range of health topics.
MedlinePlus, a service of the U.S. National Library of Medicine, provides information from the world’s largest medical library, the National Institutes of Health.