What is the main purpose of a contraction stress test (CST)?

• A. To assess uterine activity during labor
• B. To check for signs of fetal stress during uterine contractions
• C. To monitor maternal blood pressure during labor
• D. To evaluate the mother's pain threshold during contractions

Answer: (B)

The primary purpose of a contraction stress test (CST) is to check for signs of fetal stress during uterine contractions. This test is used to evaluate how the fetal heart rate responds to the stress of uterine contractions induced either through nipple stimulation or oxytocin administration.

During the CST, the goal is to monitor the fetal heart rate for any signs of deceleration or reduced variability in response to the contractions. A healthy fetus typically shows an appropriate heart rate response, maintaining or increasing the heart rate during contractions rather than showing decelerations. If the fetal heart rate demonstrates significant deceleration, it can indicate that the fetus is not tolerating the contractions well, potentially highlighting issues such as umbilical cord compression or placental insufficiency.

Uterine activity during labor is evaluated in other ways, such as through continuous electronic fetal monitoring, rather than specifically through a CST, which focuses more on fetal response. The CST is not designed to monitor maternal blood pressure or assess pain thresholds, as those are different aspects of maternal-fetal assessment during labor. Therefore, the relevant focus of the CST is indeed on fetal well-being during the stress of contractions.