Nonstress test

1. A NST is performed using an electronic fetal monitor. Testing is generally begun at 32 to 34 weeks. Testing is performed at daily to weekly intervals as long as the indication for testing persists.

2. The test is reactive if there are two or more fetal heart rate accelerations of 15 bpm above the baseline rate lasting for 15 seconds in a 20 minute period. A nonreactive NST does not show such accelerations over a 40 minute period. Nonreactivity may be related to fetal immaturity, a sleep cycle, drugs, fetal anomalies, or fetal hypoxemia.

3. If the NST is nonreactive, it is considered nonreassuring and further evaluation or delivery of the fetus is indicated. At term, delivery rather than further evaluation is usually warranted. A nonreassuring NST preterm usually should be assessed with ancillary tests, since the false positive rate of an isolated NST may be 50 to 60 percent.

0 0

Post a comment