What is one of the required criteria for performing a contraction stress test?

One of the primary criteria for performing a contraction stress test is the occurrence of three or more contractions within a 10-minute window. This requirement ensures that there is sufficient uterine activity to assess the fetal response to contractions, which can help evaluate placental function and fetal well-being. The test essentially simulates labor conditions and monitors how the fetus's heart rate responds to the stress of contractions, providing information about the fetus's oxygenation status.

Assessing three contractions allows for a reliable evaluation of patterns in fetal heart rate deceleration in response to these contractions, which helps in determining whether the fetus can tolerate the stresses of labor. An insufficient number of contractions may not provide enough data for a conclusive interpretation of fetal heart rate patterns, thereby impacting the assessment's reliability.

Other criteria, such as the duration of contractions and the use of oxytocin, serve different purposes or relate to the context of the test but aren't fundamental to establishing the test's validity as is the requirement for three contractions in that 10-minute timeframe.