Inpatient Obstetric Nurse Practice Exam 2025 – Complete Prep Guide

To consider a contraction stress test (CST) positive, the scenario must include three contractions lasting 40 seconds each within a 10-minute period. This requirement demonstrates adequate uterine activity while allowing for the assessment of fetal response to stress. A positive CST indicates that the fetus is not tolerating contractions well, usually reflected by an absence of decelerations in the fetal heart rate during these contractions.

The rationale for needing three contractions specifically ties into gaining a consistent understanding of how the fetus reacts to the stress of contractions. Each contraction should be long enough to elicit a response and ensure that enough stress is placed on the fetus to observe any potential signs of distress or reassuring patterns. This standard is set based on clinical studies that have established optimal criteria for assessing fetal well-being during contraction testing.

The other options do not fulfill the criteria required to determine a positive CST. They either include insufficient frequency or duration of contractions to allow for a comprehensive observation of the fetal heart response, leading to less reliable conclusions about fetal well-being during labor.