North American Registry of Midwives (NARM) Practice Exam

Which test is considered the most accurate predictor of uteroplacental insufficiency?

1. CST - Contraction Stress Test

2. Non-Stress Test (NST)

3. Amniocentesis

4. Doppler Ultrasound

The correct answer is: CST - Contraction Stress Test

The Contraction Stress Test (CST) is regarded as the most accurate predictor of uteroplacental insufficiency because it assesses the fetus's response to uterine contractions, which can simulate the stress experienced during labor. During the test, contractions are induced, and the fetal heart rate is monitored to evaluate how well the placenta is providing oxygen to the fetus in response to these contractions. A healthy fetal heart rate pattern during contractions indicates that the uteroplacental circulation is adequate, while abnormal responses can signal insufficiency. This direct observation of fetal heart rate response to the stress of contractions makes the CST particularly sensitive and specific for detecting issues related to placental function. In contrast, other tests like the Non-Stress Test (NST) primarily monitor fetal heart rate in a resting state without contractions, which may not provide a complete picture of placental sufficiency during the more stressful conditions of labor. Amniocentesis is not typically used for assessing placental function but rather for genetic testing or assessing amniotic fluid conditions. Doppler Ultrasound is valuable for evaluating blood flow in the umbilical artery and can provide indirect evidence of placental perfusion, but it does not give as immediate a picture of placental insufficiency under stress as