When is a Contraction Stress Test (CST) indicated?

A Contraction Stress Test (CST) is indicated when the non-stress test (NST) is atypical. An atypical NST typically shows some elements of non-reassurance, such as variable decelerations, minimal fetal heart rate variability, or other patterns that may suggest potential fetal compromise. In such cases, a CST can provide additional information about the fetus's ability to tolerate labor by assessing how the heart rate responds to contractions, helping to determine whether the fetus can handle the stress of labor.

In contrast, a normal NST does not necessitate a CST, as it indicates reassuring fetal well-being. When vaginal delivery is contraindicated, a CST would not be appropriate; instead, other management strategies would be employed based on the clinical scenario. Similarly, while a distressed fetus may merit further evaluation, such as a CST, it is more pertinent to conduct the CST when there are signs of atypicality in the NST to proactively assess the fetal condition before delivery.