A nurse is caring for a client who is pregnant and undergoing a contraction stress test (CST).
The nurse observes three uterine contractions in 10 minutes, with no late or significant variable decelerations of the fetal heart rate (FHR).
How should the nurse interpret this finding?
A. Positive CST
B. Negative CST
C. Unsatisfactory CST
D. Equivocal CST
The Correct Answer and Explanation is:
The correct answer is B. Negative CST.
A contraction stress test (CST) is performed to assess fetal well-being and how the fetus will respond to the stress of uterine contractions. This test is primarily used to evaluate if the fetus can handle labor without experiencing fetal distress, particularly concerning oxygenation and placental function. The CST observes the fetal heart rate (FHR) in response to induced contractions, which temporarily reduce blood flow to the placenta.
Interpretation of CST Results:
- Negative CST: This is the desired outcome. A negative CST indicates that there are no late or significant variable decelerations of the fetal heart rate in response to at least three uterine contractions within 10 minutes. It suggests that the fetus is likely to tolerate labor well and is not experiencing any compromise in oxygenation during contractions.
- Positive CST: A positive CST is when there are late decelerations of the fetal heart rate following 50% or more of the contractions. Late decelerations occur after the peak of the contraction and indicate uteroplacental insufficiency, meaning the placenta may not be delivering enough oxygen to the fetus during contractions. This finding would suggest fetal compromise, potentially leading to interventions like a cesarean section.
- Unsatisfactory CST: An unsatisfactory CST occurs when there are fewer than three contractions in a 10-minute period or if the tracing is uninterpretable. In this case, the test must be repeated or another method of fetal assessment used.
- Equivocal CST: An equivocal CST occurs when there are intermittent late decelerations or variable decelerations, but they do not meet the criteria for a positive CST. This may require further testing to clarify the results.
Conclusion:
In this scenario, the nurse observed three uterine contractions within 10 minutes without any late or variable decelerations of the fetal heart rate. This indicates a negative CST, meaning that the fetus is not showing signs of distress and can likely tolerate labor without significant complications related to oxygenation. This is a reassuring finding for both the nurse and the healthcare team.