What characterizes a positive contraction stress test?

A positive contraction stress test is characterized by the presence of recurrent late decelerations that occur in response to uterine contractions. This indicates that the fetus is experiencing stress during contractions, which is often due to uteroplacental insufficiency. In simpler terms, the late decelerations suggest that the baby's heart rate is responding negatively to the challenges of labor, possibly due to reduced oxygen supply caused by inadequate blood flow from the placenta.

In contrast, the other options reflect different scenarios that do not denote a positive contraction stress test. For example, intermittent late or significant variable decelerations would suggest some level of stress but not necessarily confirm the persistent issues indicated by recurrent late decelerations. Normal fetal heart rate variability indicates a well-oxygenated fetus and typically does not correlate with a positive test. The absence of any decelerations during contractions would suggest a healthy fetal response and indicates a negative test result, meaning the fetus can tolerate contractions without signs of distress.

Understanding these distinctions is crucial for interpreting the results of contraction stress tests in monitoring fetal well-being, especially in high-risk pregnancies.