The NST is usually an outpatient procedure. Interpretation of the nonstress test follows a systematic approach to include: the baseline fetal heart rate, baseline fetal heart rate variability, presence of accelerations, decelerations, and contractions. It is one of the factors that tends to disappear earliest during progressive fetal compromise. The NST recognizes the coupling of fetal neurological status to cardiovascular reflex responses. The presence of fetal heart rate acceleration with fetal movement is the principle behind the non-stress test. The frequency of use is based on clinical judgment, but is common because it is non-invasive and presents a low maternal and fetal risk however, the test does not hold predictive value and only indicates fetal hypoxemia at time of the test. The test is used to determine if a fetus is at risk for intrauterine death or neonatal complications, usually secondary to high-risk pregnancies or suspected fetal hypoxemia. The Non-Stress Test (NST) is an assessment tool used from 32 weeks of gestation to term to evaluate fetal health through the use of electric fetal monitors that continuously record the fetal heart rate (FHR). The non-stress tests can initiate at 26 to 28 weeks. The NST readings are as reactive and none reactive. Trained and certified nurses, midwives and physicians should read and interpret the non-stress test. It is a non-invasive test used for the surveillance of high-risk pregnancies when the fetus is judged clinically to be at risk for hypoxemia or increased risk of death. A prenatal non-stress test functions in overall antepartum surveillance with ultrasound as a part or component of the biophysical profile. The presence of fetal movements and fetal heart rate acceleration is the most critical feature of the non-stress test. PMID 23021694.Prenatal non-stress test, popularly known as NST, is a method used to test fetal wellbeing before the onset of labor.
#Insighttime non reactivity trial
"Nonstress testing at ≤ 32.0 weeks' gestation: a randomized trial comparing different assessment criteria".
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Confounding factors Īn NST may be non-reactive for reasons unrelated to fetal oxygenation status. "Non-reactive" is defined as fewer than two adequate accelerations during a prolonged period, which may be over an hour. Each acceleration must increase the heart rate 15 beats per minute above the baseline rate, and last for at least 15 seconds when the fetus is above 32 weeks' gestation, or 10 beats per minute over 10 seconds when the fetus is at or below 32 weeks' gestation. "Reactive" is defined as the presence of two or more fetal heart rate accelerations within a 20-minute period. A normal nonstress test will show a baseline fetal heart rate between 110 and 160 beats per minute with moderate variability (5- to 25-interbeat variability) and 2 qualifying accelerations in 20 minutes with no decelerations. Interpretation Ī nonstress test can be classified as normal, atypical, or abnormal. Vibroacoustic stimulation can wake the fetus, and is sometimes used to speed up the test or to facilitate further evaluation of a non-reactive nonstress test. The premise of the NST is that a well-oxygenated, non-acidemic fetus will spontaneously have temporary increases, termed "accelerations," in the fetal heart rate (FHR). The test is typically termed "reactive" (also "reassuring") or "nonreactive" (also "nonreassuring"). A cardiotocograph is used to monitor the fetal heart rate and presence or absence of uterine contractions.
A nonstress test ( NST) is a screening test used in pregnancy to assess fetal status by means of the fetal heart rate and its responsiveness.
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