Contraction Stress Test - Gynecology

What is a Contraction Stress Test?

A contraction stress test (CST) is a prenatal test used to evaluate the well-being of the fetus. This test helps to determine how the fetal heart rate responds to the stress of uterine contractions, which can indicate how well the fetus can handle the stress of labor.

Why is it Performed?

The CST is typically performed in the third trimester of pregnancy when there are concerns about the fetal health. It may be recommended if there are signs of potential complications such as intrauterine growth restriction (IUGR), preeclampsia, or other conditions that could affect the fetus's oxygen supply.

How is the Test Conducted?

The CST involves monitoring the fetal heart rate while inducing uterine contractions. Contractions can be stimulated using either oxytocin (a hormone that induces contractions) or nipple stimulation. The test is usually conducted in a hospital or a clinic where both the mother and fetus can be closely monitored.

What Does the Test Measure?

The CST measures the fetal heart rate response to uterine contractions. A healthy fetus should be able to maintain a stable heart rate during contractions. If the heart rate drops significantly, it may indicate that the fetus is not receiving enough oxygen, which could be a sign of potential complications.

What are the Possible Outcomes?

The results of the CST can be categorized as:

Negative: No significant changes in the fetal heart rate during contractions, indicating that the fetus is likely to handle labor well.
Positive: Significant drops in the fetal heart rate during contractions, suggesting that the fetus may be under stress and could have difficulty during labor.
Equivocal: Inconclusive results that may require further testing or monitoring.

Are There Any Risks?

While a CST is generally safe, there are some potential risks involved. The induction of contractions can sometimes lead to preterm labor. Additionally, if the test shows signs of fetal distress, it may necessitate further interventions, such as an emergency cesarean section.

When Should the Test be Avoided?

A CST may not be recommended for women with certain conditions, such as placenta previa, previous uterine surgery, or other high-risk factors that could be exacerbated by contractions. It is important to discuss any potential risks with your healthcare provider.

Alternatives to CST

There are alternative tests that can also assess fetal well-being, such as the non-stress test (NST) and the biophysical profile (BPP). These tests do not involve inducing contractions and may be considered safer options in certain cases.

Preparing for the Test

Preparation for a CST typically involves fasting for a few hours before the test. It's also important to follow any specific instructions provided by your healthcare provider. Wearing comfortable clothing and bringing a support person can help make the experience less stressful.

Conclusion

The contraction stress test is a valuable tool in assessing fetal well-being and preparing for a safe delivery. While it does carry some risks, it can provide crucial information about how the fetus will handle the stress of labor. Always consult your healthcare provider to determine the best course of action for your specific situation.