A reactive nonstress test (NST) is defined by:

A reactive nonstress test (NST) is defined by:

• A. Baseline tachycardia with minimal variability
• B. At least two accelerations within 20 minutes with a normal baseline rate and adequate variability
• C. No accelerations in 60 minutes
• D. A single acceleration in 15 minutes

Answer: (B)

A reactive NST shows that the fetus is responding normally to movement with sufficient oxygenation. This requires two fetal heart rate accelerations within a 20-minute period, and the fetus must have a normal baseline heart rate with adequate variability. An acceleration is a rapid rise in fetal heart rate by at least 15 beats per minute above baseline and lasting at least 15 seconds, with the rate returning to baseline afterward. The baseline should be in the typical range (about 110–160 bpm) and the variability should be present and moderate, indicating good autonomic control. If there are no accelerations within a long window (for example, 60 minutes) or only a single acceleration, the NST is nonreactive or inconclusive and prompts further assessment. A baseline tachycardia with minimal variability doesn’t meet the reactive criteria because it lacks the required accelerations within the specified time frame and normal baseline/variability, even though those features might suggest distress in other contexts.

A reactive NST shows that the fetus is responding normally to movement with sufficient oxygenation. This requires two fetal heart rate accelerations within a 20-minute period, and the fetus must have a normal baseline heart rate with adequate variability. An acceleration is a rapid rise in fetal heart rate by at least 15 beats per minute above baseline and lasting at least 15 seconds, with the rate returning to baseline afterward. The baseline should be in the typical range (about 110–160 bpm) and the variability should be present and moderate, indicating good autonomic control.

If there are no accelerations within a long window (for example, 60 minutes) or only a single acceleration, the NST is nonreactive or inconclusive and prompts further assessment. A baseline tachycardia with minimal variability doesn’t meet the reactive criteria because it lacks the required accelerations within the specified time frame and normal baseline/variability, even though those features might suggest distress in other contexts.